Showing posts with label Banding. Show all posts
Showing posts with label Banding. Show all posts

Friday, November 14, 2014

Fall banding 2014 (last season?)

We wrapped up the 2014 fall banding season on 30 October. This was a tad earlier than usual, but the last week was marred by deer destroying two more nets, and the sighting of yet another "stray" cat.

Is the RRBO banding program in jeopardy?
As noted in a previous post, this was a challenging season. Due to funding shortfalls, we cannot maintain the banding area as needed, and more importantly our hours have been cut. On banding days, all attention has to be devoted to tending the nets and the birds. We also had to spend time doing vegetation surveys when plants were fruiting throughout the season. As a result, time did not allow me to keep up with all my usual activities. Among things that went by the wayside were posting more regular updates to this blog and social media (I apologize!), and doing data analysis or writing the paper I am currently on, the results of our thrush diet study.

My obligation as a bander and researcher is to interpret and disseminate data we have already gathered; we need to make this a top priority. I have been tasked with raising at least $20,000 this year to maintain our current (reduced) schedule without further cuts. If we face more reductions in hours, we certainly will not be able to band next year. If we can top our goal, I hope we can resolve some of our time and resource issues and band at least part-time next fall.

How you can help

RRBO has over 2,000 people who follow us on Twitter, Facebook, or subscribe to our newsletter. Our $20,000 goal can be reached if everyone pitched in just $10! If everyone could spare $50 it would give us breathing room, and give RRBO the resources we need to accomplish our research goals.

You can visit the Support page on the RRBO web site for instructions on how to download a donation coupon, or donate online. If you'd like to donate via credit card directly through the University's secure web site just click this link. Thank you!


Will there be nets in the net lanes next year?



The fall 2014 banding summary, part 1: the birds
On to the birds. RRBO banded on 17 days between 18 August and 30 October. We utilized only about two-thirds of the number of nets we usually do, arranging them to avoid the most deer-prone areas to minimize destruction of nets and harm to birds. We still lost some nets but the damage occurred when they were closed and no injuries to birds resulted.

We captured 317 birds of 46 species. Since we tried to band on days when we hoped to maximize our captures of target species (this year, catbirds and robins), our capture rate* was 50.6 birds per 100 net-hours, the highest since 2006. However, cherry-picking days for good conditions, versus banding every day, means that we can't really compare these results with previous years.

We did succeed with our modest goal, as catbirds and robins were the top two species banded. In fact, despite the very limited schedule, our 38 new catbirds banded was a higher total than the past two years, which were dismal record lows. And we got over 40 seed samples from catbirds (more on that in the next post).

The highlight of the season was the Marsh Wren banded on October 9 described and shown in the previous post. A Blue-gray Gnatcatcher on September 15 and a Yellow-bellied Sapsucker on September 29 were other less-common species in the nets. While it's hard to judge without daily banding or surveys, all thrushes, but especially Hermit Thrushes, seemed scarce this fall, as were sparrows such as Lincoln's, Swamp, and even White-throats.

Although on my own time, I thought I would mention that I also banded at a Washtenaw County site previously used for the catbird project. Although using fewer nets than RRBO in 12 sessions for about half the number of hours, the capture rate was higher at 59.6 birds per 100 net-hours, a great result given that we did not choose our banding days based on conditions. We captured 167 birds of 27 species, with American Goldfinch and White-throated Sparrow being the top species. I am experimenting with this site for several reasons: to test the potential as a back-up for RRBO's campus site, to collect fecal samples to determine diet at a site less-invaded by non-native species to compare with RRBO's data, and to train an enthusiastic future scientist, Aspen Ellis.

Aspen is a UM-Ann Arbor student who has already accumulated a lot of varied ornithological experience: for many years she has prepared bird specimens at the University of Michigan's Museum of Zoology, and she has worked on Audubon's long-running Project Puffin as a research assistant the past two summers in the Gulf of Maine. Aspen's dedication to birds and science has been recognized by the Tim Schantz Memorial Foundation with a scholarship to Alaska to present her puffin experience, and the American Birding Association in their Young Birder of the Year contest. Read about her experiences and goals in her own words here at the eBird website.

Banding in Dearborn wasn't very practical for Aspen around her school schedule (and that of the family's cars!). But her clear commitment to bird conservation and science and her maturity spoke to me, and using the Washtenaw County site -- very near her home -- was the answer. It was a pleasure working with her. She is a fast learner and was mastering the basics as the season drew to an end; I hope we can continue the process next year.

Aspen and a female Eastern Towhee.

Part 2: the fruit data
The paper I am working on now is looking at seeds from fruits in the diets of over 300 Hermit and Swainson's Thrushes. I began with them because my previously published paper documented weight gains in these species. Meanwhile, we are still collecting data on other bird species. We have good samples sizes from catbirds (over 200), and a great data set for robins (well over 1000 from the fall seasons alone). Since catbirds and robins nest here, we would like to see if the fruit in their diets differs from the thrushes, which are only here during migration. Since we also have data for robins from summer and winter, we can also look at how their diets change throughout the year. We have also collected over 1000 specimens at the Washtenaw County site for comparison.

I will summarize a very demanding and interesting season of data on fruit availability and diet sampling in my next post.

A huge thank you to two people. First, Dana Wloch returned for yet another year of banding and seed processing. This year, measuring fruits and their seeds was added to her repertoire. In past years, she has been supported by grant money. This year, she came in several days a week as a volunteer. Truly, I would have gone insane without her.  At the Washtenaw site, my husband Darrin O'Brien forfeited his Sundays to help out banding and training Aspen. Darrin is a talented bander...and every new bander should get more than one perspective!


*In order to compare different locations or years that may operate the same number of hours but with more or fewer nets, capture rate is calculated by "net-hours." One net hour is one 12-meter net open one hour, or two 6-meter nets open one hour, etc. This rate is often expressed per 100 net-hours for more manageable numbers.
 

Thursday, October 9, 2014

Field work, fall 2014

We have been dividing our time here at RRBO censusing and measuring fruit, and banding birds in order to collect the seeds of fruit eaten by the birds.

I know you want me to show you bird stuff first!

Bird of the season so far goes to this Marsh Wren, only the second ever banded by RRBO; the other one was in 1999. Since there are essentially no marshes in Dearborn, this is not a common species here, and this is only the 7th record. Probably the coolest thing was the amazing sound this bird made. I took a short recording -  click here to listen (it's a m4a file, but I can play it with Windows Media Player).

One of the most interesting warblers I've banded lately was this adult female Black-throated Blue Warbler. In dimorphic species, sometimes older females can have relatively male-like plumage. This gal had a lot of blue tones in her feathers, a darkish face, and a very large white "hanky."


Orange-crowned Warblers are always nice -- one of the treats of late fall.



We catch very few Yellow-bellied Sapsuckers -- this is the 6th in over 20 years -- so this youngster was fun to see. Woodpeckers tend to hammer on your fingers, and the very fine, chisel point of a sapsucker bill is an effective weapon...


...although nowhere near as formidable as the powerful bill of a Rose-breasted Grosbeak. We always give grosbeaks a lot of respect!


One thing we always look at when trying to determine the age of birds is whether there is contrast between old and new feathers. In the photo above, it's easy to see the four paler, more worn wing feathers, which she has not replaced this year, and how they contrast with the new, fresher, darker wing feathers. The new feather in the middle that is a bit shorter is still growing in.

Onto the fruit. Our analyses of seeds found in the fecal samples of birds requires context: some sort of compilation and rank abundance of all the ripe fruit available to birds to eat when they are present in the area. Each year, we estimate the percent of ripe fruit on the common species once a week or so throughout the season. This year we are making sure we have complete data on all fleshy fruits available, even if they have not shown up in fecal samples -- all together around two dozen species. For less-common fruits, we have tried to locate and count all individual fruit, once a week. For abundant species, we cut down branches, counted all the fruit, and came up with an average for a "representative" branch. Then we go out and count the number of representative branches each week in a 200 meter circle centered on our banding area.

I can tell you that this work falls under both "tedious" and "easier said than done." It is not precision work (and it varies annually depending on fruit crop), so what we'll end up with is a list in approximate rank abundance, based in categories that increase by orders of magnitude. Even with that crude ranking, it's not easy and very time consuming. Much of our counting is done along a busy public bike path. People are intrigued when they see one of us standing and staring at the vegetation for long periods of time; they inevitably ask us what I am looking at. I know I have become much more adept at writing down my fruit counts and keeping track of where I am so that I can stop and explain what I'm doing.

How many ripe multiflora rose hips are just
in this one bush?
We also take various measurements of the fruits of each species throughout the season: the diameter of individual fruits, how many seeds they contain, and the diameter of the seeds. This can help us understand what size fruits are favored by different bird species, if they prefer fruits with a few large seeds or more small seeds, etc. Some fruits are simple: the shrub dogwoods are typically 5 to 8 mm, and have one seed. Then there are fruits like Climbing Nightshade (Solanum dulcamara), which have around three dozen, 2 mm seeds each! All get dutifully counted and measured. 

We start on Monday, spend at least one full day just working on fruit, and finish as best we can on days we band. Due to our funding shortfall, our days have been cut back so we are cramming as much work in as possible.

These tasks would not be possible without the help of Dana Wloch, who first started with RRBO as an undergrad, then under several grants, including one where she helped develop our seed identification website, and now is back as a volunteer. Thank you, Dana! We are the dynamic fruit duo of Dearborn.

Wednesday, November 13, 2013

Fall 2013 banding season

(Cross-posted at the RRBO web site)

Our 22nd fall banding season took place on 29 days from 15 August to 5 November. An average of 15 nets (12 meter equivalent*) were open an average of 4.6 hours per day. This is the fewest number of days we have been open in a fall season, although our modified hours were intentional -- we wanted to concentrate on maximizing the data we obtain on the fall diets of migrant birds.

Unfortunately, we also lost a 10-day period while we tried to live trap an abandoned cat that had found its way into our banding area. With the safety of birds coming first, we cannot have our nets open when we know there is a predator in the area. We brought this cat to the local shelter, where they felt it was possible it could be put up for adoption. Sadly, people dump unwanted pets here fairly regularly. This is tragic, as is the toll on wildlife taken by owned cats that are let outdoors. I've said it before, but it bears repeating: please keep your cats indoors!

Weather
Unlike some years, we did not lose much time to bad weather. I hesitate to complain, but the weather was almost too nice on banding days! The best banding conditions usually occur on calm, overcast days, often before an approaching weather front. This season, over 80% of the banding days were clear or mostly sunny.

Fall banding numbers often also have a lot to do with weather in the preceding seasons. Unlike the ridiculously wet 2011 spring and summer seasons, and the equally parched months of 2012, fall banding was preceded by a spring and summer of relatively normal temperatures and precipitation. April was cool and wet, while May was overall quite warm except for a late frost in mid-month. Average monthly temperatures for June-October were close to the recorded averages for the period 1981-2010. Precipitation for June-October was also close to average, except for August. That month, the rainfall total was nearly three inches above average, but nearly 2.5 inches of that fell on one day, August 12.

Last year's drought caused a serious lack of fruit on shrubs and trees during fall 2012. Nature often makes up for lost productivity, and did so this year. The fruit crop on most plants was abundant if not phenomenal. As noted in my last blog post, the wild grape crop was the heaviest I have seen in over 25 years. Anybody who has an apple tree in their yard can attest that after last year's near complete crop failure, apples were so plentiful that trees broke under their weight. The same was true for their very close relatives crabapples and hawthorns.

The primary non-native fruiting species here are buckthorns and bush honeysuckles. They all seemed to flower and bloom a little later than usual this year, perhaps impacted by the May frost. However, they had large crops.

I noted only two types of fruiting plants that seemed to have below-normal crops. Black cherries, which were one of the few trees that fruited well last year, took a break this year with virtually no crop. Eastern redcedars also seemed to set less fruit than usual.

Summary
As might be expected with a modified banding season, we ended up banding a modest 550 new birds and handling 87 recaptures of 58 species. This includes two species released unbanded, House Sparrow and Ruby-throated Hummingbird. A total of 741 birds were netted (which includes birds released unbanded). Our capture rate was 39.4 birds per 100 net-hours. Here is how this fall compared with the 21 previous autumn seasons:


Fall 2013 Previous
fall mean
Days open 28 50
New birds 550 1177
Total birds 741 1502
Capture rate 39.4 48.0
Species 58 69

The top ten bird species banded this fall (new captures only) were:
  1. American Robin -- 118 (low; previous mean 189.7)
  2. White-throated Sparrow --49
  3. Common Grackle -- 35 (new high; previous mean 8.8)
  4. Song Sparrow -- 33 (new record low; previous mean 55.3)
  5. Gray Catbird -- 32 (same as last year, which was record low)
  6. Yellow-rumped Warbler -- 28
  7. Hermit Thrush -- 21
  8. Cedar Waxwing --19
  9. Nashville Warbler -- 16
  10. Ruby-crowned Kinglet -- 15
Numbers and Trends
The high number of grackles is just a hit or miss event. We get very large flocks near our banding site; flocks of over 500 blackbirds, of which most are grackles, is not uncommon in October. They occasionally get flushed into the banding area, but often do not "stick" in the nets.

Banding hummingbirds requires special equipment and a permit amendment, so we release them unbanded. If we didn't, they would have come in at #2 on the list with 40 captured. Some may be repeats of the same bird, but there are often 3 or 4 in the nets at the same time throughout the season, so this is close to an accurate number. They are most often caught in nets adjacent to two plant species at which they nectar: Spotted Jewelweed, a native wildflower; and Glossy Buckthorn, a non-native shrub. The latter has small blooms from early spring through fall and I frequently see hummingbirds using these flowers.

This is the first year we have missed banding any Gray-cheeked Thrushes or Philadelphia Vireos. This may be due to the timing of our gap in banding. This is the third year in a row we did not band any Wood Thrushes. Some years ago, Wood Thrushes were common nesting species here. This is a species that is declining over much of its range, and their absence here may reflect those diminishing numbers.

Both Swainson's Thrushes and Gray Catbirds continued a long-term decline in our nets that I have written about previously. Scrolling down on this page will present graphs on these two species, plus Hermit Thrush; the trend remains the same.

Last year I noted declines in our capture rate* over the last decade. For the first 13-15 years of banding, things moved up and down, but usually remained over 40 birds per 100 net-hours. The average for the years 1992-2004 was 51.6. Since 2005, there has been a pronounced drop. In fact, the drop was quite steep from 2005 to 2008, and since then it has more or less fluctuated in the 30-40 range.

Click to enlarge.

Two important things happened around 2005 that may help explain this: first, the bike path that runs through campus -- wrapping around 3 sides of the banding area -- opened. It gets a great deal of traffic. Second, we began experiencing canopy loss due to falling ash trees killed by the Emerald Ash Borer. This dramatically changed the character of the forested area at UM-Dearborn. Not only did it result in a different mix of trees and shrubs, but probably created a more open and inviting habitat for our increasing deer herd, which alter ecosystems themselves.

So many changes have taken place around our banding site over the years, including the construction of several nearby buildings, and a large, busy parking lot adjacent to the net lanes. Increased development, habitat changes at the site and landscape level, higher numbers of mammalian predators, weather events... it's not possible to tell what may be responsible for our declining capture rate. No doubt it is a combination of things, and we will be pondering the future direction of the banding program in the months to come.

Highlights
We have only banded 6 Golden-winged Warblers in the past 21 fall seasons, so this bird on September 10 was a treat, and our first since 2005.


The past ten years of so, Northern Waterthrushes seem to be a little scarce, and some years we do not band any. Even just the four we banded this fall was better than we've done since 2006.


An interesting Orange-crowned Warbler was banded on October 14. It had large, distinct dusky centers to its undertail coverts. This is a feature more characteristic of the subspecies that is resident in California, and I've never seen it on any of the birds I've banded here in migration. Bill measurement can be helpful in distinguishing subspecies, and while this one was a little large, it was within the high end of the range of the subspecies expected to pass through Michigan.


A Sharp-shinned Hawk banded in mid-September.



Recaptures
Twenty-three individuals of 9 species of passage migrants (those which do not normally nest or winter in this area) were recaptured. Sixty-five percent of them maintained or gained mass. Half of the birds that lost mass were sparrows. This is fairly typical of this site; insectivores and frugivores tend to gain weight, while seed-eaters tend to lose weight, or gain just small amounts.

We also recaptured 13 birds banded in previous years. The oldest was a female Northern Cardinal first captured in October 2001, making it over 12 years old. Another old bird was a female American Robin first banded as an adult in 2008. She is at least 6 years old. You can view more longevity records here.

Seeds!
We obtained another 318 seed samples from 11 species of birds. This included two new "contributors": a Brown Thrasher (which had eaten pokeweed and grape) and a Willow/Alder Flycatcher (which ate honeysuckle). This brings our total sample size to more than 1,500. Over half are from American Robins, and other large percentages from Gray Catbird, Cedar Waxwing, and Hermit and Swainson's Thrushes.

Credits, kudos
Finally, I’d like to thank Dana Wloch, this year's assistant, and her sponsor, the Michigan Audubon Society. This is the second year in a row MAS has supported Dana's work helping with banding, completing many more species accounts on our seed identification website, and her continued work with our fall dietary study cleaning, sorting, identifying, measuring, and cataloging fruits and seeds. This banding season would not have happened without MAS and Dana, and the on-going work of RRBO could not continue without the support of many donors.

THANK YOU!


*In order to compare different locations or years that may operate the same number of hours but with more or fewer nets, capture rate is calculated by "net-hours." One net hour is one 12-meter net open one hour, or two 6-meter nets open one hour, etc. This rate is often expressed per 100 net-hours for more manageable numbers.

Weather statistics from the National Weather Service.

Friday, September 27, 2013

Update on fall banding and fruit research

We are a little more than halfway through our modified fall banding. This year, we are concentrating on obtaining as much data as possible on the diet of fall fruit-eating birds. Many bird species switch from a summer diet made up primarily of insects to a fall diet heavy in fruit. This abundant, easy-to-eat food source is particularly important to migratory birds.

After our research showed that migratory thrushes gain weight during stopover at our campus study site, the next step was to pinpoint what resources these birds were using while they were here. Fortunately, there is a reliable and low-tech way to find out: identify the seeds in their poop. (You can find more details by following the links above.) We began collecting samples from thrushes in 2007, and from all birds in 2009. As of the end of last year, we have collected samples from 1,208 birds of 16 species. That's nearly 8,000 individual seeds, of which fewer than a dozen have gone unidentified (see the post on our seed website for more information on how we identify seeds).

Although these seem like big numbers, we need to make sure we have large enough samples sizes from individual bird species during certain time periods to make sure we can do proper statistical analyses. This way, we hope to answer a number of questions, especially whether or not particular species prefers certain fruits and if some fruits help birds gain more weight than other fruits.

This fall, to maximize number of samples we have modified our usual banding routine. When we have done comprehensive migration monitoring, we begin banding very early in the morning, which is when we tend to catch the most birds. Typically, birds captured the first hour or so have not had time to eat much, so we did not obtain many samples from them. This year, we are starting later in the morning and staying open later in the day, providing more overlap with bird foraging. We'll also aim to spend more hours during peak migration/fruiting periods -- late September to mid-October. Overall, this means we will probably band fewer birds, but get more samples.

So far over the 16 days we have banded this fall, roughly a third of all birds have contributed a sample. If we only consider those species most likely to eat fruit -- the primary species are American Robin, Gray Catbird, Cedar Waxwing, and the thrushes, but there are others that eat fruit less often -- the percentage jumps to over 65%. We have collected over 500 individual seeds.

Fruit crops fluctuate from year to year. Last year, the very early spring warm weather and the summer-long severe drought devastated fruit crops.  This year much more normal rainfall and temperatures has resulted in bumper crops of fruit. Some are especially impressive: branches are sagging under the weight of crabapples (both wild and ornamental) and the wild grape crop is nothing short of phenomenal, the largest I have seen in over 25 years.

Not a vineyard! Wild grape crop.
Many factors go into fruit choice in birds: fat, sugar, protein, and micro-nutrient content; size and color; pulp-to-seed ratio; and abundance are just a few. Not surprisingly, the dominant seed in our samples this fall so far is grape, present in 65% of samples. As the crop is depleted and other fruits ripen, the proportion will decline, but no doubt it will be higher than any other year so far. In past years the percentage of grapes has ranged from 5 to 19%.

Grape seeds provided by an American Robin.
This winter we will be doing our first statistical analyses of our samples to see what our data looks like. Stay tuned!

Monday, August 5, 2013

Summer banding 2013

RRBO has done very little summer banding over the years, as we have not had any research projects that require banding during the breeding season for quite some time. This summer, however, our catbird project had us out in the field catching catbirds...and of course we banded whatever else we caught while doing so.

First, we successfully captured enough catbirds to carry all 26 of the geolocators obtained through Dr. Bowlin's grant. On campus, we did targeted netting in a location near Fairlane Lake by setting up a few nets in the midst of the territories of several pairs of catbirds. I also set up our usual fall banding area over a month earlier than usual and the bulk of the catbirds were banded there. In total, at UM-Dearborn we banded 21 catbirds: 7 adult males, 5 adult females, and 9 hatching-year birds. We also captured 5 catbirds (2 adult males, 2 adult females, and 1 hatching-year bird) at a remote site off-campus in Washtenaw County.

Aside from catbirds, we banded 72 other birds of 16 species. The highlight was two hatching-year Orchard Orioles caught in the same net on July 24. This doubles the number of Orchard Orioles banded on campus since 1992; the other two birds were adults caught in the spring. This is an uncommon but annual species here. This year, they seemed more numerous than usual, and apparently nested on campus or close by.

One of the young Orchard Orioles banded this summer.
An adult female American Redstart banded on July 17 was a surprise. There was no physical evidence that she had nested, but it was only our second July record.

We tend not to band many Yellow Warblers in the fall (our 21-year average is 3) because they start to move south quite early in the season. A total of 5 for our modest summer banding was a nice number.

My impression is that House Wrens are having a good year, and we banded a dozen. This is just under our fall seasonal average. We'll see how the fall numbers look.

Our fall banding season begins in mid-August. We will be concentrating on maximizing the data we obtain on the fall diets of migrant birds. We will be banding fewer but longer days, and focus on times of peak bird movement and wild fruit set. After last year's drought-induced fruit crop failure, most fruiting plants are loaded this year. Because we had prolonged cool weather this spring, ripening is a little late, but it should be a very interesting season.

Thursday, November 15, 2012

Fall 2012 banding season review

Our 21st fall banding season took place on 38 days from 17 August to 25 October. An average of 17 nets (12 meter equivalent*) were open an average of 4.3 hours per day. This is the fewest number of days we have been open in a fall season, as we lost 14 whole days and curtailed many others due to rain, heat, or wind, including the last week or so of the season due to Superstorm Sandy and her winds (see below).

Weather**
What we band in fall has a lot to do with weather in the preceding seasons, even those in years past. I'll leave aside the amazingly wet spring and very hot summer we had in 2011 -- not that they can't have lingering effects, but the weather in 2012 was unusual enough. 

We started the growing season well ahead of schedule, with an unprecedented March heat wave. I discussed possible effects in this blog post. Then came the extended hot, dry summer. It began with 11 days over 90 degrees by the end of June resulting in an average temperature for the first six months of the year being the warmest on record for Detroit. Record heat in July (13 more days over 90F) and precipitation well below normal created severe drought conditions (D2 on the U.S. Drought Monitor scale). 

Below is a map at roughly the end of the breeding season for many songbirds showing drought conditions throughout North America.

Click here for the original map in detail from the North American Drought Monitor.
Banding begins in mid-August, and while the month was still warmer and drier than average, most of the month's precipitation fell as we began the season. September was cooler (although still slightly above average) and remained drier than normal. October brought two episodes of high winds, one mid-month and the other at the end of the month as a result of Hurricane/superstorm Sandy. This ended our banding season.

Summary
We ended up banding just 616 new birds and handling 72 recaptures of 63 species (includes two species released unbanded, Ruby-throated Hummingbird and House Sparrow, and one species, Downy Woodpecker, in which we only had a recapture and no new individuals banded). A total of 725 birds were netted (which includes birds released unbanded). Our capture rate was 27.5 birds per 100 net-hours. Here is how this fall compared with the 20 previous autumn seasons:


Fall 2012 Previous
fall mean
Days open 38 51
New birds 616 1205
Total birds 725 1541
Capture rate 27.5 49.0
Species 63 70

Bold indicates the lowest numbers in our history for fall banding -- we'll give this some analysis in the trends section, below.

The top ten bird species banded this fall (new captures only) were:
  1. American Robin -- 107 (low; previous mean 188)
  2. Song Sparrow -- 37
  3. Blackpoll Warbler -- 36
  4. Gray Catbird -- 32 (new record low; previous mean 138)
  5. American Goldfinch -- 32
  6. Swainson's Thrush -- 30 (low)
  7. Magnolia Warbler -- 27
  8. Hermit Thrush and American Redstart -- 26
  9. White-crowned Sparrow -- 21
Our biggest day was on 16 October, when over 100 birds were banded -- 20% of the total that had been banded up to that point. The next day...just 8 birds! In fact, there were only 4 other days when more than 30 birds were banded.

Highlights
Let's start out with good news. First, we had our first new species for the banding program in a long while. This handsome male American Kestrel was the first banded on campus by RRBO, and represented the 123rd species banded since 1992.


Connecticut Warblers are always a treat -- especially good-looking adult males like the one below, banded on 19 September.


What started out as a gruesome discovery on 28 September had a happy ending. We captured a Swainson's Thrush that had a piece of straw (hay) impaled through its eyelid and the skin past the ear hole. It was embedded at that point, the skin beginning to grow around it. This must have happened at least several days prior to our catching it, when the bird was foraging in some area with straw strewn about. Amazingly, the eye itself was unharmed, there was no infection, and the bird was in good condition.

Before.
Under magnification and in just a few minutes, I snipped off most of the exposed straw, severed it where is crossed the ear, extracted the portion between the ear and eye, and finally snipped it close to the point where it was embedded in the skin. I removed over 30 mm of straw! The bird flew off, hopefully to continue a successful migratory journey without the threat of the straw getting caught on something and ripping the skin or puncturing the eye.

After.
Among the 21 White-crowned Sparrows banded this fall was this candidate that had the clear-lored look of the western "Gambel's" form. However, it has the bill shape and color that lean toward more typical eastern forms. This is the first adult of this type we've banded; for a full discussion and more photos see this page on the RRBO web site.

"Gambel's" White-crowned Sparrow?


Trends
The RRBO banding program has focused on bird community composition and various metrics relating to the condition of migrant birds at our site. Thus, overall numbers have not been a main theme for us. Limitations and biases inherent in migration banding cannot be overcome, and much has been published in the literature cautioning against the sole use of banding data to monitor bird population trends. However, it's always interesting to take a look at trends of some species, especially in a year like this with unusual climate events and very low numbers. We just need to take it with a grain of salt.

Of the 25 species of which RRBO has banded over 200 birds, five were banded in greater than average numbers and the rest were below average, when effort was considered*. A half-dozen of these species are among our most commonly banded, and all those were banded in numbers far below normal. Low numbers of a few of them (Hermit Thrush, Song Sparrow, American Goldfinch) could be attributed to the premature ending of the banding season, when I tend to band quite a few of these species. Let's look at the others.

Both Swainson's Thrushes and Gray Catbirds continued a long-term decline in our nets that I wrote about last year. Catbirds in particular I think may be responding to landscape-scale habitat changes being engineered by a burgeoning deer herd.

I'm not sure what to think of the -74% departure from normal of White-throated Sparrows. While they do persist longer in the season here than White-crowned Sparrows (many overwinter), they have been scarce at local feeders as well. This is the first fall season when White-crowns outnumbered White-throats, which are typically banded in three times the numbers. If I had to pick a reason, I would guess that White-throated Sparrows, since they most often feed on the ground, may have had trouble finding leaf-litter invertebrates due to dry conditions. This would be especially true during migration, but it could have impacted them on the nesting grounds as well.

Early in the banding season, I wrote about the lack of young birds being banded. This usually indicates low reproductive productivity. Typically, 81% of the birds we band in fall are young-of-the-year (or hatching-year, HY, birds). This year, just 72% were HY. A look at American Robins, our most commonly-banded species, is instructive.

We've banded nearly 4,000 robins in fall, and roughly three-quarters are HY. This year, the figure was just 46%.


I think this is likely attributable mostly to the drought, as robins rely heavily on leaf litter insects and soil invertebrates (such as worms) to feed their young.

Another interesting metric appeared late in the season. By mid-October, most robins have completed molting -- young birds will have lost their distinctive breast spots and adults will have completed molting their wing feathers. This year that was not the case.

Young robins with breast spots after 10 October:
1992-2011: 2.9%
 Fall 2012: 25%

Adult robins still molting primary feathers after 10 October:
1992-2011: 16.1%
Fall 2012: 25%

This indicates that many robins nested later this season. I expect this was due to re-nesting after lost broods (because of the drought), perhaps additionally influenced or initiated by the mid-August rains.

Finally, while I've already provided the caveat that our banding program is not designed to accurately monitor population trends, I have to look at the overall trend in our capture rate for the last eight fall seasons:


Prior to that, there were ups and downs but our effort and capture rate remained fairly stable. We have been banding in the same location all these years, and strive to keep the vegetation structure at its original stage of succession. This may be an indication that populations of the species we typically band in fall are truly declining, and/or that the landscape surrounding our banding area is changing through urbanization, fragmentation, the interactions of deer and canopy loss due to emerald ash borer, or a combination of these and other factors. The value of long-term data collection is having these trends to look at, even if we are not sure how to interpret them at this time.

Recaptures
Twenty-two individuals of 10 species of passage migrants (those which do not normally nest or winter in this area) were recaptured. Seventy-seven  percent of them maintained or gained mass.

The old man cardinal. More RRBO longevity records here.
We also recaptured 13 birds banded in previous years. The oldest was a male Northern Cardinal first captured as a second-year bird in April 2001, making it 12 years old.

Six Gray Catbirds from the past were recaptured; there were two from 2008 that were both originally captured as adults. A Downy Woodpecker first banded in 2006 as an adult at least three years old was also back again.

Finally, I’d like to thank this year’s banding crew: Shelley Martinez, Mike Sullivan, and Dana Wloch. RRBO couldn’t operate without you!




*In order to compare different locations or years that may operate the same number of hours but with more or fewer nets, capture rate is calculated by "net-hours." One net hour is one 12-meter net open one hour, or two 6-meter nets open one hour, etc. This rate is often expressed per 100 net-hours for more manageable numbers.

*Weather statistics from the National Weather Service.

Wednesday, October 10, 2012

Banding update

We are well on our way to banding the fewest birds in any fall season in 20 years! The fewest new birds we have banded prior to this year was 739 in 1996. Our "slowest" year was actually 2008, when our capture rate (birds banded as a function of the number of nets we used and the number of hours we had them open) was 33.4 birds per 100 net hours. You can see our current numbers in the right sidebar. I'm pretty sure there is not enough time left in the season for this year not to come in dead last in both categories.

While a lack of birds is disappointing (and kind of alarming), these low numbers are providing valuable data.The weather this growing season is mostly responsible, in particular the drought.  In a previous post, I noted the low numbers of young birds we were banding. This has continued to be the case. American Robins in particular have exemplified the kind of season we are having.

The average number of robins we band in fall is 188, with 300 or so not being uncommon. Prior to today, we had banded only 15!! Today we had 17 more, bringing our total to 32, a remarkably low number.

Based on our 1992-2011 fall data, we can expect around 76% of the robins to be hatching-year birds. This year it is only 23%. This is an indication that robins failed to fledge a "typical" number of young. Since many of the robins we are catching now are migrants likely to have nested elsewhere, this suggests that nesting failure was not just a local problem. And indeed, the drought covered a very large part of the continent.

One interesting aspect is that nearly half young birds I have captured recently still had some spotting on their breasts; this is the plumage they have when leaving the nest. Typically, only about 3% of hatching-year birds have spots this late in the season, having already mostly completed their fall molt. Similarly, 61% of the adult robins are still completing their fall molt. In the past, only about 16% were still molting at this time of year. It looks like, then, that many robins nested late this year -- probably after losing an earlier brood.  It's possible that the skewed ratio of young to older birds may even out a bit in the next couple of weeks.

The prolonged and severe drought contributes to low reproductive success by diminishing food supplies, especially for birds like robins that utilize a lot of leaf-litter or soil invertebrates to feed their young. Besides just reducing the number of birds available, the dry weather contributes to our low capture rates by impacting the fruit crop. Our very early spring heat wave also compounded the failure of many types of wild fruit, as I discussed earlier in the season. Fruit is a vital food source for many species of migratory birds, and of course, a main topic of our research.

In short, many of our staple fruiting plants had small crops or did not fruit, or fruited later than usual. I noted that locally, fruit crops were better in areas adjacent to water. Our banding site is not (unlike many banding stations, which are located in some sort of coastal situation). So this year provided interesting insight into the impacts of growing season weather.

In a future post, I'll provide an update on the 2012 fruit crop and what we found birds were eating.

Friday, September 7, 2012

August banding

Fall banding 2012 started on August 17. As I suspected, things have been slow. The very hot, dry summer seems to have resulted in low reproductive productivity for our most common local breeding bird species, such as American Robins. It's just difficult for them to find ground-dwelling invertebrates to feed their young when it is so dry.

Rather than just summarize numbers this fall banding season, I'd like to focus more on one of our current research projects: the fall diet of birds. As regular followers know, RRBO's research focus is on the fall stopover ecology of migrant birds, in particular what kinds of fruit birds are eating in this urban forest patch. We do this by collecting seeds passed by the birds that we band when they poop in the bags we transport them in. This is the 6th year we have collected samples from Catharus thrushes (Swainson's, Gray-cheeked, and Hermit), and the 4th year we have done expanded sampling on all bird species.

Through 2011, we have collected samples from over 1,000 birds of 17 species. Of the nearly 6,400 individual seeds in these samples, only nine have gone unidentified (I'll describe in detail in a future post how we identify all the seeds). Twenty plant taxa are represented in the samples, and most seeds have been identified to species. Thus, we have a great picture of which species of fruit are being eaten by birds.

Pokeweed fruit.
In August, we collected samples from 18 birds. Pokeweed was the most common seed, showing up in 11 samples. We had our first ever sample of poison ivy from a catbird. Usually, this is consumed by woodpeckers or Yellow-rumped Warblers, and nearly always in October. Like quite a few plant species, poison ivy seems to have flowered (and thus set fruit) earlier this season. Other plants may have budded or flowered early (given the long stretch of hot weather in March), then failed to fruit either due to frost in April, or because of the long dry period in summer. We have virtually no crop of wild grapes or relatives such as woodbine/Virginia Creeper. A number of other shrubs that are staples in the diets of fall birds here are ripening late; some portion of shrubs did not set fruit at all.

Poison ivy flowers

Our data for this hot, dry growing season should be an interesting contrast to last year's exceptionally wet summer and add substantially to our picture of what birds eat during fall in an urban natural area.





Monday, November 14, 2011

Fall 2011 banding wrap-up

Our official fall banding season ended on 8 November. I had really hoped to squeeze in a few more days, but the wind or rain prevented me from doing so. I have posted a full summary with photos and stats on the RRBO web site.

Because we had a number of nets that were damaged by deer, instead of trashing them I moved them all into one area and decided to leave them up a little longer. As we have some warm days in November and December, I hope to catch a few more robins (and maybe even a wintering Hermit Thrush) to see what fruit they continue to eat as winter sets in.

As we identify and compile our seed samples from this fall and add them to our database, expect to see a blog post or two on what we have found our birds to be eating. Plus, a couple of exciting projects are being to come together, and of course our winter bird survey is also fast approaching. Stay tuned.

Monday, October 24, 2011

Fall banding: Weeks 8-10

Good riddance to a wet September. October has been occasionally wet or windy, but overall the weather has been much better. Unlike some Octobers, we have had only two mornings with frost, which can delay us from opening in the morning if the nets get stuck shut. On the downside, deer are mating and they've managed to get in the banding area regularly. One night a buck was presumably chasing a doe and they ran into the gate of the chain link fence so hard they bent open the latch! We are now operating with a reduced number of nets, and all but two of the ones remaining are damaged from their activities.

The number of birds we have banded so far in October represents over 40% of the total for the season. Most have come after mid-month, when American Robin numbers increased, and the first big push of Yellow-rumped Warblers, Hermit Thrushes, and sparrows began. It is heartening to see respectable Hermit Thrush numbers. The number of Swainson's Thrushes banded this fall was our second lowest. We have already hit our average for Hermit Thrushes, and are getting plenty of seed samples from them, which is excellent. We're still below average for White-throats, and they don't seem as numerous this year as usual. We have only banded four White-crowned Sparrows, which is ridiculously low. Our average is 22.

White-throated Sparrow.

Warblers continue to be banded. In addition to Yellow-rumps, late species such as Common Yellowthroat, Orange-crowned, and Palm still are around, as is Tennessee. Every day we still get a Nashville Warbler or two, and we are far over our fall high of 59 Nashvilles banded. Notable was a Blackpoll Warbler banded on 22 October that tied the late fall date for Dearborn -- but one seen the next day furnished the new late date. An American Redstart was also banded  on 22 October, and that was a new late date for that species.

Orange-crowned Warbler.

Two species were banded this month that we don't get too often: Eastern Towhee and Yellow-bellied Sapsucker.


Young male Eastern Towhee.

Young female Yellow-bellied Sapsucker.
We are now around 1000 new birds banded of 72 species, approaching average but with a capture rate (based on number of nets and hours opened) still well below average. Typically we band into the first week of November, but we may go longer than that this year if the weather holds. The next banding update will be a summary of the season.

Tuesday, October 11, 2011

Barred Owl in Dearborn

[2017 update at bottom of post]

I get a fair number of calls to help rescue birds from various situations, often inside buildings. Usually they are very common species (European Starlings, in particular, seem to have a knack for falling down chimneys). Often there isn't much I can do but offer advice, which is often sufficient to solve the problem.

Late yesterday afternoon I got a message from Jim Barber at the First Presbyterian Church of Dearborn, directly across the Rouge River from campus. They had a large owl (he thought Great Horned) trapped in the basement boiler room of the church. He was at wits end -- the bird had been there for at least several days and nobody he called was taking any action. The notion of a Great Horned Owl getting down a ventilation shaft seemed pretty unlikely to me, and he told me the room was around 20 by 20 feet with high ceilings. This seemed like a difficult situation, but my curiosity, the plight of the bird, and Jim's frustration compelled me to immediately head up to the church and figure out how I could help.

Within 15 minutes I was looking in the boiler room. Not only was it big, it was cluttered with all sorts of equipment and supplies. This was the part of the room I saw when I walked in:

To the right was the large boiler, and the ceiling went up another 10 feet, criss-crossed with pipes and supports. A large owl did indeed take off from a ceiling beam and fly over to a pipe above the boiler. To my great astonishment it was not a Great Horned Owl (or a Cooper's Hawk, which I sort of expected), but a Barred Owl (Strix varia), a species with only a single record from Dearborn, in 1976 (see history, below).

I decided there were two possibilities for catching the owl. One, with a long-handled net, although with so many obstacles I thought this might result in a lot of chasing around, which would stress the bird. The other was to use a bal-chatri trap, a common way of catching raptors. Bal-chatris are wire traps topped with small nooses made of fishing line. A mouse is placed in the trap, and when the raptor pounces on the trap it gets its talons caught in the nooses. The mouse isn't harmed, and the bird can be quickly released from the nooses. I figured the owl would be very hungry after three days, and this should work pretty well.

After outlining my plan, I called my husband Darrin O'Brien to have him bring a bal-chatri from home as well as a net for back up. I also called my good friend Jim Fowler. Jim has a great deal of experience handling raptors, and also spent 30 years at Greenfield Village as the head of the grounds department, rescuing plenty of birds from buildings. He would bring a long-handled net and a second bal-chatri. I went up to the RRBO banding lab on campus to fetch my banding gear.

When we all reconvened at the church, a member of the Michigan Humane Society wildlife department had shown up. He and the church employees had ambushed the owl and had it wrapped in a shirt, saving us a great deal of trouble. We took the owl from him, and after one loud screech, it settled down and stared up at Jim, who held it while we checked the bird's condition and I measured the wing.


Considering its ordeal, the owl was in great shape. It had some fat, and had no injuries or even broken feathers. Jim Barber and his co-worker Jamie told us there were certainly mice in the boiler room (and they also put out water for the owl), so we can only assume it probably ate while holed up.

Darrin took the bird so we could band it.


I let Jim Fowler do the honors. While it looks like Jim's nose might be in danger here, it's really the talons you have to worry about. Sure enough, it did grab Jim's thumb at one point, drawing blood.



Outside the breeding season, Barred Owls cannot be sexed, so we don't know if the owl is a male or female. But looking at the color, shape, and wear of the wing and tail feathers can help determine age.

All the wing feathers and their coverts (the row of feathers covering the bases of wing feathers) are quite uniform in color and wear, which indicates that this is a hatching-year (HY) bird. The outer six wing feathers (primaries) are slightly more worn that the inner four, but that might be due to flying around a room full of close objects and brushing against them. Further, at no age would we really expect all the inner primaries to be replaced and the outer primaries retained. The shape of the primary coverts is rounded, with the pale areas more round than block-shaped, also an indication of HY.

In the photo above, we can count the number of pale bars on primary number 9, the second feather from the outside. Five bars are visible, not counting the pale tip. In the first set of wing feathers on a Barred Owl, p9 will have 4 to 5 bars; there will be only 3 to 4 bars on it after it is molted. This feather might be molted in the owl's second fall, or not until the third fall. This owl was not actively molting any wing or tail feathers. If it was older than HY, it should have been molting some feathers, or there should have been some new wing feathers that looked different -- less worn with narrower bars spaced further apart.

The photo above not only proves I was actually present at this event, but also shows the pointed, whitish tips of the tail feathers. These are the first tail feathers, which will probably not be replaced until the bird's third fall molt, after which they will have darker, blunter tips and narrower bars. All of this leads to my conclusion that this is an HY bird. By October 10, we would expect that any flight feather molt would be nearly or fully complete, so if it were an older bird, we would see the contrast in old and new feathers discussed above. It's always tricky determining the age of a bird with which you have no experience, so I'm happy to take any corroboration or contradiction in the comments!

We walked to the edge of the parking lot to release the owl. It took flight and landed in a tree, shook itself, gave us one last look, and took off toward the Rouge River and UM-Dearborn campus. 

Barred Owls in Wayne County

According to historical accounts, Barred Owls nested in Wayne County until about 1910, after which they were apparently extirpated, being hunted and pushed out by agricultural and urban development. The next record I found was a report from the UM-Dearborn campus on 12 May 1971. I was unable to confirm the veracity of this record, but it was by a reliable observer. The only reliable report I have had from Dearborn is a bird seen on 7 April 1976 by Gary Hutman on land that is now the TPC Golf Course. Over a decade passed before a report came from Grosse Ile on 27 December 1987. In 1994, one was seen at Lake Erie Metropark by my husband Darrin on 17 September.

In recent years, Wayne County reports have become more frequent. Daryl Asprey found one at Crosswinds Marsh (phase 1) on 6 December 2003. When RRBO was coordinating the breeding bird atlas work for the county, one or two were reported calling in a wooded area in Canton Township from 2004-2006; we were never able to confirm nesting. Several years ago, a pair took up residence at Oakwoods Metropark, first heard calling by Daryl Asprey on 23 February 2007. Feel free to add any further records in the comments.

Thanks to everybody who participated in this rescue. Good luck to the owl, and to the guys who I understand will be on the roof of the church today, closing off a certain ventilation shaft...

Update: I had a report of a Barred Owl being heard at the far north end of campus on 23 April 2017.   

Saturday, October 1, 2011

Fall banding 2011: Weeks 6 and 7

The month of September drew to a close on a windy, rainy note -- the 9th full day of banding missed this month due to weather. Notable mid-way through the season is the near total absence of sparrow migration, with only two White-throated Sparrows banded so far, and no noticeable movement of Swamp, Song, or Lincoln's Sparrows.

Thrush migration has also been dismal. Gray-cheeked Thrushes are never numerous, and Hermit Thrushes have yet to arrive, but Swainson's Thrushes (left) are one of our bread-and-butter birds. Our average for Swainson's Thrush is 70, and a number of years we have topped 150. Our lowest year we caught 24, and we are tied for that number right now. It sounds like other banding stations are also below average. South of us, Black Swamp Bird Observatory was at 131 Swainson's Thrushes as of mid-month, and their mean is 480. If you have any thoughts or observations on thrush migration in the eastern U.S., please feel free to leave a comment! Looks like we'll have to put in at least one more year to increase our sample sizes for our dietary study.

Speaking of which, many trees and shrubs are still laden with late-ripening fruit. I don't ever recall having any substantial crops of arrowood (Viburnum dentatum) or elderberry (Sambucus canadensis) into September, yet these trees have had fruit most of the month, some still coming ripe. The Amur honeysuckle (Lonicera maackii) crop, a non-native, is still only about half-ripe. On the final day of September, I found multiple plants of this species, as well as gray dogwood (Cornus racemosa), woodbine (Parthenocissus inserta), and Japanese honeysuckle (L. japonica) still blooming! This year we have large crops of wild grapes (Vitis spp.), poison ivy (Toxicodendron radicans), and non-native climbing nightshade (Solanum dulcamara). Does anybody else think fruit crops are a little tardy this year?


Good numbers of warblers, relatively speaking, are still moving through, although we have yet to see Yellow-rumped Warblers in any numbers. This past week we exceeded our high number of Nashville Warblers (above), with 60 banded so far (our fall mean is 28). Two more uncommon species were also banded this period.

 This Connecticut Warbler was banded on 27 September...


...and so was this female Blue-winged Warbler. The Blue-winged is actually much rarer here in fall than the Connecticut. This is only the fourth Blue-winged Warbler we've banded in fall, whereas we've banded over two dozen Connecticut Warblers.

A reader asked for an update on the condition of American Robins, since I mentioned in our week 1 summary that the young robins we were catching were quite emaciated. For the month of August, the average weight of young robins was a full 5 grams below the average for previous Augusts. For August and September combined, it was about 1 gram below average. However, our sample size for this fall is very low. The ratio of young robins to adults is very out of whack. Normally for August-September, 75% of the robins we band are young. This year, it's only 36%. This is really surprising, since productivity (as judged by the multitude of young robins we saw this summer) seemed very high. What happened to them? Was there high mortality among other underweight robins? Unfortunately, we will probably never know.

Let's hope October brings us better weather, and more robins, catbirds, and thrushes!

Thursday, September 22, 2011

Geolocators on catbirds

Geolocators are tiny devices that measure light levels for up to two years. This data can be used to calculate latitude and longitude when compared with sunrise and sunset times and light levels at noon in different geographic locations. They are accurate to about 200 km for latitude, with better resolution for longitude.

When mounted on a bird, a geolocator records light intensity data at intervals throughout each day. Retrieved later, the data can be downloaded and migration routes, pace, and destination can be determined. For species with broad breeding and wintering ranges, this can provide important information on exactly where particular breeding populations spend the winter. Given that we have long-term Breeding Bird Survey data indicating that populations of some species are declining in particular regions of North America, figuring out where these birds spend most of the year helps us identify what may be causing their declines, and helps us devise more effective conservation measures.

This fall, RRBO is placing geolocators on a sample of summer resident Gray Catbirds. This project is a joint effort between RRBO and Dr. Melissa Bowlin, who joined the UM-Dearborn faculty late last year and who is a research partner of the Environmental Interpretive Center. Dr. Bowlin's interest is in how physical traits of birds influence their migratory performance. In our catbird study, she will be looking at how the wing shape of individual birds impacts the pace of their migration. The geolocator data will allow us to determine the time it takes for each of the birds to reach their wintering destination, and hopefully where the birds stop each day, so we can calculate the rate of migration for each bird.

RRBO is interested in the approximate route followed by catbirds breeding in this area, as well as where they spend the winter. Previous data from other researchers have indicated that Midwestern catbirds winter in Central America, whereas catbirds Mid-Atlantic nesting catbirds winter in the southern U.S. and the West Indies. This information is based on small sample sizes: recoveries of 17 banded birds and 6 birds with geolocators. Our data will add to this knowledge. 

The geolocators are tiny, and are carefully fitted on the birds with a flexible harness that loops around the bird's legs. The total weight of the geolocator plus the harness is less than a gram, or about 2.5% of the weight of an average catbird. The recommendation for any kind of radio transmitter or attachment to a bird is 4% or less. The geolocator rests just above the bird's rump. Dr. Bowlin has done careful studies, published in the journal Methods in Ecology and Evolution, determining the effect of drag and weight of various types and configurations of geolocators, using preserved bird bodies in a wind tunnel. The set-up we are using is the best available configuration to minimize these effects.

A geolocator, attached with a leg harness, above the rump of a
catbird at RRBO. The little wand pointed toward the tail is
the part with the light sensor.

When the feathers are smoothed out, only the light wand
sticks out.
Catbirds were chosen for this pilot project because it is not only our most frequently banded long-distance migrant, but also because we recapture a lot of individuals in subsequent years. This is critical because in order to get the data, we have to recapture the bird next year, remove the geolocator, and download the information! Geolocators are typically put on nesting birds, because they have the highest probability of returning to the same site in subsequent years. RRBO banding data has indicated that both adult and young birds (hatching year) captured in early autumn, after hatching year birds have become independent, also have a high return rate. This study will also help us determine if deploying geolocators on hatching year or post-breeding birds is viable. If so, it could help expand the use of these devices by migration banding stations that do not operate during the breeding season. Since we are putting geolocators on both adult and young of the same species from the same population, we hope to also see if age is a factor in the choice of migration route or wintering site.
Because the geolocators are hard to see in the field (the arrow
is pointing to the wand on this one), catbirds are also getting
a single green color band to help us relocate them next year.
(The dark "mustache" on this bird is a juice stain from a meal
of berries!)

As you can see, the potential for these little devices to unravel basic life history mysteries is huge. The pioneering study with bird and geolocators was done by Dr. Bridget Stuchbury and published in the journal Science. The study looked at Wood Thrushes and Purple Martins, and is summarized here. Geolocators are being used to study Bicknell's Thrushes, Bobolinks, Red Knots, Ruddy Turnstones, and Golden-crowned Sparrows, among other species.  Much more information on this technology, as well as the importance of what we can discover is available at the web site of the Migratory Connectivity Project.

We plan to offer donors an opportunity to sponsor these catbirds. To be included in our fall campaign, add your name to the RRBO mailing list.