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.

Wednesday, July 24, 2013

Update on catbird research

In 2011, RRBO embarked on a collaborative research project with Dr. Melissa Bowlin, a member of the UM-Dearborn Natural Sciences faculty. Dr. Bowlin had a number of geolocator devices left over from a previous project. Geolocators are tiny devices that measure light levels. 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 can be placed on a bird, and if the bird can be recaptured the following year, the data can be downloaded and migration routes, pace, and destination can be determined. You can read a full explanation of how geolocators work and the goals of the project on the RRBO web site.

In 2011, we placed 11 geolocators on catbirds. In spring 2012, we resighted 3 birds with devices, and recaptured 2 of them.

We did get data from the 2 retrieved geolocators. As it turns out, the data was not high quality; not only do catbirds spend a fair amount of time in shaded areas, but the light-collecting stem on the devices we used was a little short and we suspect ended up being covered by feathers a good amount of the time. Without a good reading on the light, the data from one was deemed inaccurate. The other bird seems to have wintered in Florida -- which is unexpected as preliminary data from other researchers (based on banding and geolocators) indicates that Midwestern-nesting birds winter in Central America. We put the geolocator on this bird on September 29, 2011, it appears to have left Dearborn on October 12, arrived in Florida on the October 16, left the wintering grounds on March 30, 2012, and arrived back in Dearborn on May 8, 2012. We recaptured it May 17, 2012 (here's the story of its recapture).

In fall 2012, we put 2 more geolocators on birds, but did not see any birds with geolocators in spring 2013, despite a lot of patient observation of the catbirds on site.  Earlier this year, Dr. Bowlin received a grant to purchase 26 new geolocators with longer light-collecting stems better suited for catbird study. You can see the older device below in the top picture, and a newer one with the longer "stem" in the bottom photo. They both weigh the same, 1 gram including the harness.



During my spring bird surveys, I spent time locating territories of catbirds that I thought would be easiest to catch and re-find next year. Two of Dr. Bowlin's students, Kelli Gutmann and Quen Watkins, then staked out these birds to see where they tended to hang out so they could be captured with a minimum of fuss. I also set up our regular fall banding site, and began banding a month earlier than usual.

We have had good success so far this summer. We have put 14 geolocators on resident catbirds. Even more exciting, one of the birds I recaptured was a male with a geolocator from 2011! The batteries on the devices can last for 2 years, so if it is good quality we could conceivably get 2 years of data from it. 

We feel confident we can catch enough catbirds for all of our devices, and look forward to finding out what routes they use on migration; if the routes differ for males and females, or adults and young; where the birds stop during migration and how long they stay at each stopover; and where they spend the winter. Stay tuned for more updates!

Friday, July 19, 2013

Yellow-headed Blackbird in Dearborn

Last week, a local man, Ron Prowse, came in and spoke to a co-worker (I was off campus) regarding an unusual Blue Jay-sized bird he had seen at his bird feeders on June 12. He provided this photo.

Photo by Catherine Prowse. Not to be used without permission.
Based on the picture and the description he provided my co-worker, we conclude that this is a Yellow-headed Blackbird (Xanthocephalus xanthocephalus), a new species for the Dearborn bird list!

Yellow-headed Blackbirds are typically a more western species that nests in the grasslands and marshes of the Great Plains. They have nested regularly in Michigan in small numbers for at least 50 years. The most notable small breeding populations are in the Saginaw Bay area. The closest location they are typically found is at Pt. Mouillee State Game Area in Wayne/Monroe Cos.

Map of eBird sightings in the Lower Peninsula of Michigan
for the year 2013.
If I were expecting to see a Yellow-headed Blackbird in Dearborn (which I was not!), I would presume I'd see it during spring migration. A July date is quite interesting, as it would be at a point in their breeding cycle when young are leaving the nest. This wandering bird could be an adult whose nest failed elsewhere, or a non-breeding adult. The most recent sighting at Pt. Mouillee put in eBird was on July 13.

The observer's location not far from the TPC Golf Course along the Rouge River. This portion of the river is channelized, but there is a small wetland on TPC property adjacent to the channel that does have nesting Red-winged Blackbirds and waterfowl. Perhaps the bird was/is hanging around there. Yellow-headed Blackbirds are very tied to cattail marshes for nesting, so the habitat is probably inadequate for that, but it might be a good place to pass the summer.


View Larger Map

Hats off to the Prowse's for this great observation!

This is the 258th species documented for Dearborn. For an interesting historical perspective on Yellow-headed Blackbirds in the state, see Why are Yellow-headed Blackbirds rare in Michigan? by Richard Brewer.

Tuesday, April 30, 2013

Let's talk turkey

Turkey track found at the north end of Fairlane Lake
next to my notebook for scale.
(Update at end of post!)

On April 16, a Wild Turkey was reported on campus. It was seen twice at Fairlane Estate, once at the feeders behind the EIC, and I found a track at the north end of the lake (right). For one morning, this bird really got around!

Wayne County has had many turkey reports in the last few years, mostly from Sumpter Township and nearby areas in the southwestern part of the county. These probably originated from the successful re-introduction and restocking of turkeys by the Michigan Deptartment of Natural Resources in northern Monroe Co. Back when RRBO was working on the Michigan Breeding Bird Atlas, we obtained data on the relocation of nearly 150 turkeys from Barry, Cass, and Washtenaw counties to Monroe County (a few to St. Clair County) between 2002-2005.

Over the past winter, it seems like turkeys were on the move. Reports came from Belle Isle and near Willow Run airport. This spring, there more reports from Willow Run and environs, and on April 26, someone photographed a turkey on a fifth-floor window ledge near Ford Field in downtown Detroit! I suspect Detroit-area birds come from Canada, including from Fighting Island in the Detroit River, where a large flock has been released. And now Dearborn joins the list of Wayne County communities with a turkey sighting.

I did not include Wild Turkey in my book on Dearborn birds; they did occur here historically, but the book included only those species with specific documentation. Most long-time Dearborn residents are familiar with the pioneer memoir of William Nowlin, The Bark Covered House. Although Nowlin's circa 1840 homestead was just outside Dearborn city limits, it no doubt depicts the turkey situation in the region at the time.  In one passage the author notes,
"Sometimes I would rise early in the morning and go out of the door just at daylight. ... I would listen to see if I could hear the gobbling of the wild turkeys. I hardly ever failed to hear them, sometimes in different directions. I frequently could hear two or three at once."
Turkey poop in my Washtenaw Co. yard with the
toe of my boot for scale. Kind of like Mourning
Dove droppings, but lots bigger.
Alas, by the turn of the 20th century, Wild Turkeys were pretty much gone from Michigan, primarily from overhunting. In the 1950s, a program was initiated to reintroduce turkeys into Michigan. The state population is now around 200,000 birds. An interesting side note: occasionally, one sees grayish or whitish turkeys, which some people believe means wild turkeys have interbred with domestic turkeys. In fact, this is an uncommon genetically-linked color form that was brought to southern Michigan from turkeys relocated from Iowa in the 1980s.

Perhaps ironically, the MDNR is now moving turkeys from southern Michigan to northern Michigan to both bolster populations and to rid urban areas of "nuisance" turkeys. Admittedly, turkeys are very large birds that can do a bit of damage scratching in gardens. And their poop is pretty big, though not as voluminous and messy as goose poop, in my opinion. But despite periodic horror stories, Wild Turkeys are pretty wary and urban areas really don't provide adequate habitat for them.

Nonetheless, the situation reminds me of all the efforts to re-establish and foster populations of White-tailed Deer or Canada Geese, which are now over-abundant and troublesome in many urban areas. I wonder if stories like this will become more common, and what the fate of Wild Turkeys in populated areas will be if their populations flourish.

UPDATE

A (the?) hen turkey was seen again along Fairlane Drive near the old stone cottages on May 2, where Dr. David Susko took the photo at left. There was a very large outdoor event on campus that day, so she probably didn't hang around, but this seems to indicate that she may be hanging around the area.


Thursday, March 7, 2013

Winter Bird Population Survey 2012-2013

The 21st year of RRBO's Winter Bird Population Survey has been completed. Over the late-December to late-February survey period, 39 species were tallied. The previous annual average number of species is 38. We added yet another new species this year, a Merlin recorded on 19 December*. This brings the total cumulative species list for 21 years to 73.

Comparing this season's results to the previous 20 years, a few things stand out. First, the number of American Robins was the lowest since 1995. Only previous two years have had lower numbers than this year. While many people still think of robins as harbingers of spring, a lot of robins will winter in southern Michigan so long as they have a food supply -- temperature itself is not the limiting factor. I looked at historical climate data (average temperatures and precipitation for December and January) for the past 20 years and found no correlation between any combination of these weather data and the number of robins counted each year.

For robins, food supply primarily means fruit. Due to the long drought over the summer of 2012, the fruit crop this season in our area was quite poor. Additionally, fruit set was diminished because of the unusual warm period in March, when some fruiting plants set fruit very early, or bloomed but failed to set fruit because pollinators were not yet on the wing.

This robin has staked out some wild grapes.
Photo by alsteele under a Creative Commons license.

For the past 20 years, the mean number of robins seen over the winter survey season was 348, with a mean of 28 robins per visit (each season the area is surveyed/visited an average of 14 times). This season a total of only 47 robins and 3 birds per visit were recorded. The highest counts (although still fewer than 20 individuals) came the last two visits of the season, when robins began to coalesce into larger flocks and move back into the area.

Pine Siskins provided another highlight, this one more positive. This species has only been recorded in three previous years, and this year they were present on all but one visit and in numbers greater than 20 birds each visit prior to mid-January. This winter was excellent for many "winter finches" although strong numbers of siskins were not predicted for this region.

The lack of recovery of American Crows in Dearborn from West Nile Virus (WNV), which first showed up here in 2002, continues. A group of three American Crows flying over campus on January 1, 2013 were the only ones recorded all season. Nine out of the last ten years have recorded fewer than ten crows all survey season. My 2011 post provides more background on the crow decline.


On the RRBO web site, you can find the full results of all 21 years of surveys, along with information on the protocol.

*Technically, this survey is supposed to take place from 20 December to 20 February.  Due to weather and scheduling difficulties, we ran it from 19 December to 21 February this season.

Friday, January 11, 2013

Dearborn portion of Detroit River CBC, 2013

Frozen Fairlane Lake on the University of
Michigan-Dearborn campus.
The Detroit River Michigan-Ontario Christmas Bird Count was held, as it is each year, on January 1. This was the 36th year for the count, which is centered at I-94 and Warren Ave, and the 19th year that RRBO has coordinated the field work in the city of Dearborn.

The day began on a high note. As usual, my husband Darrin O'Brien and I drove friend and participant Cathy Carroll to her starting point, so she can walk along the west side Rouge River back to her car on campus. Due to the fact I have just turned old enough to join the AARP (or, perhaps, a lack of coffee), we drove her to the wrong spot! My dunder-headedness turned out to be serendipitous, as I spotted an adult Bald Eagle perched in a tree along the Lower Rouge River just west of Evergreen Road. As we pulled over to admire it, I got a call from my co-worker Rick Simek, who was covering the south end of campus. He excitedly told me he had just flushed an adult Bald Eagle! Later, Greg Norwood, covering the north end of campus, also saw the eagle; Cathy saw it again later, too. While eagles are getting more and more common in the county and the city, this is only the third time we have recorded this species on the count.

Darrin and I traditionally cover the Ford "sunflower" fields which can vary in productivity from year to year depending on which ones are planted, and with what. Usually, the most productive field is the original field at Hubbard and Southfield. However, the last few years it has been planted in hay. (Curiously, given the very high prices and demand for hay this year due to the drought, the hay was still being stored on-site in the field.)  Sometimes a cover crop is used for winter, but this year it (and the one across the street) was left fallow, save for a narrow fringe of sunflowers along the edges, long since picked over.  There wasn't much at this field, nor any of the others except the one adjacent to Ford World Headquarters.


Hay bales stacked up in one of Ford's fields; The Henry hotel at Fairlane Town
Center in the background.
It seemed that every seed-eating songbird in the city was stuffed into that field along Michigan Avenue. Over 200 Red-winged Blackbirds were there, along with over 3,500 House Sparrows; yes they are tedious to count and require at least two hours of multiple estimates. Prior to these fields being planted in 2002, we would tally a few hundred House Sparrows on the entire count. Now it's usually over a thousand, and this year's total set a record. Here's how the last 17 years* look:

House Sparrow numbers on the Dearborn portion of the Detroit River CBC,
adjusted for effort. The dip in 2010 was due to a rainy day with poor
counting conditions.
All these small birds in one place are very attractive to raptors. At this field were several Red-tailed Hawks, an immature Cooper's Hawk, and a lovely adult Peregrine Falcon, seen earlier in the day winging to this spot from the Oakwood Hospital area. The most unusual species seen at this location was Mute Swan: five were seen flying over and heading east. This is only the second count on which they have been recorded.

The horse paddock at Greenfield Village once again yielded Horned Lakes (five).  Darrin spotted one first, and it prompted this exchange:

Darrin: I have one. It's on the pile of poop to the left of the side door.
Julie: Got it. And here's another...now three...four...five.
Darrin: What?! Are you on the same poop that I am?

The best time to look for interesting birds at the Greenfield Village horse
paddock is right after they are fed, and hay piles are strewn about.

Lest you think Dearborn is entirely pastoral, here is a photo approaching the massive Ford Rouge complex, often considered the birthplace of mass industry in North America. The city is really more concrete than natural habitat, and in fact we need fewer people to cover it than we used to a decade ago.


The summer drought played a role in our bird sightings. The soft mast crop (berries and other fruit) was the poorest I can remember. Our 66 American Robins was the lowest number we've counted since 1999; the average over the last decade is over 250.

The drought may also be partially to blame for the widespread tree crop failure (seeds, cones, and other hard mast) this year. Earlier in the season we experienced movement of just about every "winter finch" through the area in search of food. Many kept going, but at least a few hung around. Our total of 23 Pine Siskins on campus was part of a flock that has been either visiting the feeders or feeding on European Alder cones. This was only the fourth count they have been recorded, and this is a record number.

Surely the highlight of the day was also one of the wandering winter finches: ten White-winged Crossbills on a spruce tree in Detroit River CBC compiler Jim Fowler's back yard. This is a new species for the count, bringing the Dearborn cumulative species total to 86.

We ended the day with 47 species, which is one above average. We added a count week species the next day (Brown-headed Cowbird) at the campus bird feeders.

The complete results of the Dearborn portion of the 2013 Detroit River CBC can be found at the RRBO web site on this page, which includes historical results. I've written summaries here at Net Results for the 2012, 2011, 2010 and 2009 counts.

You can read an analysis of the first 25 years of the overall count in this paper:

Craves, J. A., and J. A. Fowler, Jr. 2003. Twenty-five years of the Detroit River Michigan-Ontario Christmas Bird Count. (pdf) Ontario Birds 21:109-128.


*Although RRBO has been coordinating the Dearborn portion of the count since 1995, we've only had uniform coverage of the city since 1997.