Showing posts with label Research news. Show all posts
Showing posts with label Research news. Show all posts

Friday, September 1, 2023

Michigan's Threatened and Endangered bird species

 

There has been a revision of the threatened and endangered species list for the state of Michigan. Many of the changes in the lists below were first formulated in 2015, but the state legislature did not act on them. They were revisited in 2019 but the finalization was delayed by covid. I co-chaired the committee in 2015, and chaired it in 2019.

To determine changes or additions in the threatened and endangered species, a techinical committee reviews available data from multiple sources, and applies criterion that utilize those data in close association with the state conservation status rankings. This is the system used by NatureServe and its member Natural Heritage programs, in our case the Michigan Natural Features Inventory. The legislation underpinning endangered species protection in Michigan can be viewed here, and the state's public comment period announcement that briefly outlines the entire process is here.

Generally, the list reflects elevations or new listings of species whose populations or state ranks have deteriorated in recent years, or downlistings of species whose populations or state ranks have improved. Some adjustments have also been made to rare species that are at the edge of their breeding ranges in Michigan, but have healthy populations elsewhere. This represented a change in how we looked at species, but the criteria are now more standardized, objective, and hopefully favor a more proactive rather than reactive approach. I'd have to say there are a few changes I'd propose to this list today based on additional data or new knowledge coming to light just in the last few years. 

The revised bird list as of 2023 is below, with changes noted. For a complete list of all of Michigan's Threatened and Endangered Species, including plants, click here.

Endangered
King Rail
Piping Plover
Long-eared Owl - elevated from threatened
Short-eared Owl
Barn Owl
Loggerhead Shrike (migrant subspecies)
Henslow’s Sparrow

Threatened
Spruce Grouse - elevated from special concern
Eastern Whip-poor-will - elevated from special concern
Yellow Rail
Common Gallinule
Upland Sandpiper - new
Caspian Tern
Black Tern - elevated from special concern
Common Tern
Forster’s Tern
Common Loon
Least Bittern
Northern Goshawk - elevated from special concern
Peregrine Falcon - downlisted from endangered
Evening Grosbeak
Louisiana Waterthrush
Kirtland's Warbler - downlisted from endangered
Golden-winged Warbler - elevated from special concern
Cerulean Warbler

Special Concern (no legal protection)
Trumpeter Swan - downlisted from threatened
Northern Bobwhite - new
Sharp-tailed Grouse
Common Nighthawk
Wilson’s Phalarope
American Bittern
Black-crowned Night-Heron
Northern Harrier
Bald Eagle
Red-shouldered Hawk - downlisted from threatened
Red-headed Woodpecker
Black-backed Woodpecker
Merlin - downlisted from threatened
Boreal Chickadee - new
Sedge Wren - new
Marsh Wren
Wood Thrush - new
Grasshopper Sparrow
Yellow-headed Blackbird
Eastern Meadowlark - new
Prothonotary Warbler
Connecticut Warbler - new
Hooded Warbler
Prairie Warbler - downlisted from endangered
Dickcissel 

Species removed from lists
Osprey - was special concern (populations improved)
Western Meadowlark - was special concern (edge of range)
Yellow-throated Warbler - was threatened (edge of range)


Wednesday, February 8, 2023

20 years of European Goldfinches = 1 big paper

 

Craves, J.A., and N.M. Anich. 2023. ­­­Status and distribution of an introduced population of European Goldfinches (Carduelis carduelis) in the western Great Lakes region of North America. Neobiota 81:129-155. doi: 10.3897/neobiota.81.97736

This paper is open access, so you can read it online or download the PDF by clicking the title above. (The figures look better in the PDF.)

 


The backstory is on this page.

Friday, January 25, 2019

European Goldfinches and other cage birds in the Western Great Lakes

European Goldfinches in Kenosha, WI, April 2016
Photo by Darrin O'Brien
  

I have posted an updated page on European Goldfinches and other non-native cage birds in the western Great Lakes. I am still collecting follow-up data while the Wisconsin Breeding Bird Atlas is in its final year of surveys; southeast Wisconsin and northeast Illinois are the "epicenters" of the breeding population of European Goldfinches. I'm working on a summary paper -- read all about the history, identification, and how to submit reports here.

Thursday, September 7, 2017

New major paper published

The paper Native birds exploit leaf-mining moth larvae using a new North American host, non-native Lonicera maackii was recently published online ahead of print in the journal Écoscience.

This paper describes the interactions between native birds, a specialist moth, and the moth’s new host in North America, Amur honeysuckle, a problematic non-native shrub.

On a bird survey in late fall 2015, I came across a small flock of chickadees that appeared to be finding food on the leaves of Amur honeysuckle along the Rouge River. This non-native shrub dominates the forest understory in this area, as it does over a large swath of North America east of the Great Plains. The feeding behavior was very interesting to me, as Amur honeysuckle is known to be largely free of insect herbivores, even more so than the other species of non-native honeysuckles that are so common in urban forests.

A closer look revealed that nearly every Amur honeysuckle had leaves that were heavily infested with leaf mines, and that the chickadees were opening these mines and feeding on the insects within them. This was even more intriguing! Because they live and feed within plant tissues, leaf mining insects tend to be very host-specific, and specialized insects like this were supposed to be especially rare on most introduced plants, Amur honeysuckle included.

I reared the tiny caterpillars, overwintered them, and had the emerging insects (which were moths) identified by DNA barcoding in 2016. I continued my observations on bird use of the moth larvae, the extent of the infestation, and population status in 2016. My paper details these findings, which are novel in several ways:
  • This is the first record of this moth species, or any in the same moth family of over 2000 species, using Amur honeysuckle as a host in North America
  • The native ranges of the moth and the shrub do not overlap, indicating evolutionary adaptation was involved in the host switch
  • Some of the bird species using the moth larvae have never been documented feeding on leaf mining moths
  • Because Amur honeysuckles holds leaves (with occupied mines) until well after killing frost, these larvae supply protein to birds at a time when other insects have become scarce
In the paper I also discuss the ecological implications of these interactions. I am continuing to make field observations on bird predation, and am raising moths to see which other local hosts in the same plant family they might use. One interesting fact about these moths is that they are all female. This method of asexual reproduction is not particularly common in butterflies and moths, and is not only handy for me (to raise them, I don't have to worry about pairing them off), but also means a single female can be a founder of a large population. I'm also working with a Canadian researcher on identifying the parasitoid community -- the many tiny wasps that lay eggs in the larvae within the mines; there have been four species identified so far. At least one more paper is in the works.

This link will take you to the abstract of the paper. If you'd like to read the full paper, please contact me by using the form in the footer.

Many other papers can be downloaded at my Researchgate profile.

Friday, December 18, 2015

Seed-a-palooza

Time for an update on the seed and diet study -- one in which may explain why blog posts have been so infrequent over the past year.

Recap of RRBO's research trajectory
When RRBO was founded in 1992, there was very little research being done on how birds used urban natural areas. Our first task was to establish solid baseline data on the species, relative abundance, and seasonal distribution of birds using the UM-Dearborn campus utilizing historical data, standardized regular surveys, and bird banding. This has resulted in a variety of publications, including a book, documenting the 261 species of birds found in the city of Dearborn, mostly on campus.

Once we understood that many birds used the area, our next question was: How? Were migratory birds that stopped here able to find the resources that would enable them to continue their migratory journey? Based on our banding data, we looked at 15 years of recaptures of thrushes during fall migration, and found that all three species for which we had sufficient data -- Gray-cheeked, Swainson's, and Hermit Thrushes -- did gain enough mass to make the next leg of their migratory flight. This research was published in 2009 in The Wilson Journal of Ornithology.

That led us to another question: What were these birds eating that helped them gain weight? Fortunately, there is a reliable and low-tech way to find out: identify the seeds in their poop. Over 300 samples consisting of over 1200 seeds were analyzed from Hermit and Swainson's Thrushes, and a paper summarizing the results is in progress. The majority of samples were from two non-native plant species, Amur Honeysuckle and Common Buckthorn. This was a little surprising, because these species were said to have little nutritional value to birds.

Every "answer" leads to more questions!

Current research
Our thrush work led me to begin working on the following...

Were fruits being eaten in proportion to their abundance in the landscape?
Last year I finished up censusing fruit in a large plot to provide us with a sense of the rank abundance of all the ripe fruit available to birds to eat throughout the fall season. The end of this post describes that work.

Were there some intrinsic characteristics (size, number of seeds, etc.) of the fruits that made some more apt to be consumed than others?
This fall and winter I will be finishing up the fruit morphology work, which I first described in detail in this post. I will have detailed data on many physical characteristics of the fruit of 40 species of fall-fruiting plants, based on measurements of over 6500 fruits and over 9000 seeds (so far!). I'll be preparing a paper on this data for The Michigan Botanist.

Were migratory thrushes eating non-native fruits because resident birds had already eaten the "better" native fruits before the thrushes arrived?

In 2009, we started collecting fecal samples from all bird other species we banded. Two things became immediately clear. First, other birds began eating honeysuckles and buckthorn as soon as they became ripe, even when native species like pokeweed and dogwoods were available. Second, we could collect A LOT of samples from American Robins.

Robins have been RRBO's most commonly banded species, although they are poor subjects for mass gain studies. We rarely recapture them and we cannot distinguish which nested in the area and which were migrants (thus making it impossible to estimate stopover duration and obscuring mass gain patterns).

Since we don't need to rely on mass gain data, we don't need to capture robins and can use "seed traps" to collect robin samples. Often, seed trap arrays are plastic trays with drainage and screen tops placed throughout an area frequented by birds. This is a costly method in an area like ours where field equipment is frequently vandalized. Fortunately, robins have the habit of gathering at drinking and bath sites, during which time they nearly always poop. We began collecting samples from robins when we were able to observe a flock around puddles or foraging in a specific area within our study plot. When a small retention pond was constructed right outside the banding lab, we set  out boards along the margins -- these made excellent seed traps! In 2013, we also began collecting samples at a Washtenaw County site which has more native fruiting plants and fewer non-natives (especially honeysuckle) to use as a comparison, using similar methods.

This fall, 949 samples were collected from robins, bringing the 2009-2015 fall total of samples to 2207 consisting of 16931 seeds, of which only one was unidentified! And why stop in fall? Robins are here nearly year-round, so we have continued to collect in winter, and have 350 samples (2252 seeds). At the Washtenaw County site the total number of robin samples is 1135 (6327 seeds) for fall and 792 (4515 seeds) for winter just over the past two years. Summer samples are being collected as well, although fewer plants fruit in summer. Samples are also collected from all species banded at the Washtenaw site.

So far, altogether, from both sites for all species throughout the year, RRBO has collected and compiled data on over 5300 samples consisting of over 35000 seeds.

This very robust data set will show us what fruits robins eat (and therefore disperse in the landscape) throughout the year in both an urban and more rural setting. 

Because fruit crops vary from year to year, I want to continue the collection (especially in winter) for at least another year. I'll have to draw the line at some point in order to dedicate some large blocks of time dedicated to data analysis, rather than data collection!

Tuesday, November 18, 2014

Fall 2014 fruit and seed work

I mentioned in a previous post that 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. In that post, I described our fruit counting methods.

Fruit morphology
Another aspect of our work this fall was describing various morphological characteristics of the common species of fruit available at our site. Many factors go into fruit choice by birds. Among them are the size of the fruit, how many seeds it contains, and the size of the seeds.

Some of these data are available in the literature. As I searched for these metrics, I found that for some species different sources reported quite different numbers, some sources had data on one characteristic but not others, while measurements for some species were not to be found. The best, though not the easiest, solution was to take measurements ourselves. Weekly, we collected around 10 fruits from each of around 30 species, measured the fresh fruit, counted the seeds per fruit, and measured the seeds. Dana Wloch started this project last year, and it was expanded this year. I'll be finishing up with some of the late fruiting species next week, but so far we have measured about 3300 fruits and over 7000 seeds!

Some of our results are basic. For example, the average diameter of the five most common seeds in fecal samples (Common Buckthorn, Amur Honeysuckle, American Pokeweed, Riverbank Grape, and crabapple) is 8.2 mm. This agrees with other studies that have shown bird-dispersed fruits typically average about 8 mm.

Some results are much more intriguing. Glossy Buckthorn is a non-native species that can be quite invasive, especially in wetlands. A recent study from its native range in Sweden stated the average diameter of the fruits was 8.7 mm (458 fruits) with an average of 1.7 seeds per fruit. We measured 134 fruits here over two years, and the average both years was 7.7 mm. The average number of seeds for 168 fruits was 2.5.

Glossy Buckthorn fruit does not ripen simultaneously, so red,
unripe fruit are often on the same branch as black, ripe fruit.

Glossy Buckthorn has been shown to have evolved different morphological characteristics in different parts of its native range. This species has been present in North America for over 200 years. If our data is truly representative of the local population, it might suggest adaptation to a different suite of dispersers, exposure to more or better pollinators, and the higher seed set may be a factor in its success as an invader. All speculative at this point, but no doubt it will prompt me to continue measuring Glossy Buckthorn!

Seed samples
Meanwhile, during the fall season, we collected 453 fecal samples from 6 bird species. However, over 80% of the samples were from robins that we did not band. Several years ago, the University began cleaning off all sidewalks and roads on a daily basis in fall. In a number of areas, low spots in the pavement hold water and attract robins, which often then "leave a deposit." Collecting these samples in communal bathing and drinking areas, as well as along other paths where we observed robins foraging on the ground, is a convenient way to acquire a lot of data.

For catbirds, the top four species in our 41 samples this fall were:
  • American Pokeweed (native)
  • Riverbank Grape (native)
  • Amur Honeysuckle (non-native)
  • shrub dogwoods (native)
This closely follows the rankings for the 5 previous years combined. Pokeweed and grape have ranked #1 and #2, while the shrub dogwoods have been #3 and Amur Honeysuckle and Glossy Buckthorn are close together at #4 and #5.

Sample sizes for robins are much higher. This fall the 453 samples revealed the top four species as:
  • Amur Honeysuckle
  • Common Buckthorn (non-native)
  • crabapples (non-native)
  • Riverbank Grape
These four species are also the same top four species from over 900 samples from previous years, although Common Buckthorn has been the top ranked species for those 5 years.

Two other species in robin samples were notable. Previously, Multiflora Rose (non-native) was found in 4% of samples; this year it increased to 6%. This is interesting considering a number of Multiflora Rose has been reduced in the past year or so both by removal and from infection by rose rosette disease. We also have the native Illinois or Climbing Rose (Rosa setigera) here. There is overlap in the appearance of seeds of these two species, but there are fewer R. setigera, their hips are larger and "ripen" later than multiflora. I believe most of the seeds found in fall samples are probably multiflora.

A comparison of the large hips of the native Rosa setigera (left) and the
small hips of non-native Rosa multiflora (right).
Asiatic Bittersweet (non-native) was previously found in less than one percent of samples. This year, it was in 5% of samples, a rather large jump. This species has also been the target of removal the last couple of years. The capsules encasing the fruit usually open fairly late in the season, and did not seem much earlier this year (first date in samples Oct 8) than the average (Oct 16). Thus, neither increase in the number of plants nor early fruiting seems to explain the higher proportion of samples with bittersweet.

Asiatic Bittersweet is especially conspicuous when there are no leaves on trees.

One possible explanation for the increase in these two species is that robins are eating more of them because a great deal of their top-ranked species (buckthorn and honeysuckle) have been removed in the larger landscape.  However, annual fluctuations due to weather and crop size can be large, so it will take more years of sampling to see if this year was just a quirk, or if trends will start to appear.

I haven't done much digging through the numbers yet, but even this quick look is pretty interesting. 


Wednesday, April 30, 2014

RRBO's work on Detroit Public Television

Detroit Public Television and The Nature Conservancy have partnered to produce a series of programs on topics of regional environmental importance called Great Lakes Now Connect. Coming up next week is their program on migratory birds, and Julie Craves and the work of the Rouge River Bird Observatory are among the featured scientists.  Here is a terrific preview:


Or you can view it here.

Please note that in this preview, and I assume in the program as well, I have received an "educational upgrade." I don't want to misrepresent myself: I do not have a doctorate, a fact that unfortunately didn't make it to the final editors of the show. This lack has presented a major challenge over the years, as I do not have the access to funding that is more readily available to faculty members or other more highly-credentialed researchers. Yet without the benefit of more traditional academic support, RRBO has made scientific contributions meaningful enough that our work can be included with that of amazing people like Michigan's own Dr. Dave Ewert and Dr. Jen Owen. That's due in very large part to RRBO's faithful and generous donors, making RRBO a truly community-based conservation organization.

Please enjoy the preview, and watch the program -- it will live-stream on GreatLakesNow.org on Tuesday, May 6th from 1 to 2 PM. EST.

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!

Monday, October 22, 2012

Our online seed guide

As regular followers know, RRBO's primary research focus is the ecology of fall migrant birds in urban areas, and one of our main project is examining the fall diet of birds at our urban site.

To do this, we collect fecal samples from the birds that we band, and identify and catalog all the seeds we find. We initially compiled a book of photos of seeds from plants known to occur in the area, as well as a large reference series of seeds collected on campus and nearby.  This has enabled us to identify all but 9 out of nearly 6,500 seeds we have collected in fecal samples from 2007 through 2011.

Although our big binder of seeds and photos was handy, we found we also wanted to have other reference material in it. We also found there was a lot of interest in this project from other researchers as well as land managers and homeowners interested in what birds are eating. We conceived an online reference guide that would include all this information in the form of species accounts.


Thanks to support from the Jimmy F. New Foundation and the Michigan Audubon Society, our web site is coming together. You can take a look at the first set of species accounts: Fruit Seeds of Southern Michigan.

The guide provides accounts of plants that produce fleshy, bird-dispersed fruits, with special emphasis on the identification of seeds. It will focus on fall- and summer-fruiting plant species found in southern Michigan, but since many of these species are widespread in North America, it will be useful for a broader region. Both native and non-native species are covered.

The financial support has provided a stipend for UM-Dearborn graduate Dana Wloch to work on the site. As a student, Dana worked for several years collecting and compiling seeds from our banded birds under two independent research projects. As the "Number 2 of Number 2" she is uniquely qualified for this task, and I'm grateful for her help and work on the web site, as well as sorting through, identifying, and compiling all the seeds pooped out by every species except the Catharus thrushes for the fourth year in a row.


Take a look at our site. It's a work in progress, so there will be many more species added, revisions to the existing accounts, and the bibliography and resource pages will be completed.

Monday, May 21, 2012

Catbird success!

One of our research projects at RRBO is a joint project with Dr. Melissa Bowlin, a faculty member here at UM-Dearborn. Last fall, we placed light-level geologgers (or geolocators) on a sample of Gray Catbirds on campus. Catbirds are one of our most frequently banded birds. These tiny devices measure light several times daily. If placed on a migrating bird, they will record data that can be used to calculate latitude and longitude when compared with sunrise and sunset times and light levels at noon in different geographic locations.

This data can give us a wealth of information on the pace and route of migration, and wintering areas. You can read all about how they are used on the RRBO web site. 

There is a catch (pun fully intended). In order to get the data, the bird must survive a full migration, return to the original banding location the next year, and be recaptured so the geolocator can be removed and the data downloaded. Last fall, we placed a colored leg band on each of the catbirds which also carried a geolocator, so we could more easily re-find any birds that returned this year.

Well, I couldn't have been happier to find one of our color-banded catbirds singing right behind the Environmental Interpretive Center (EIC). Once I was sure he was going to stay put, I set up three nets between two of his favorite singing perches. While I was setting the nets up, I caught a catbird I presumed might be his mate. It was banded, and turned out to be a bird we banded as a hatching-year bird in August 2008.
Nets set up on either side of the driveway to the rear of the
Environmental Interpretive Center. Hard to see? Good!
Very early the next morning it was time to try to catch "the" bird, and Dana Wloch and Darrin O'Brien joined me. Often, territorial male birds will investigate another singing individual of his own species. We placed an iPod playing a loop of a singing catbird behind one of the nets. Sometimes that's enough, but it usually helps to have a stuffed "singer" near the recording. I didn't have a stuffed catbird handy, but I did have a study skin of a European Starling.  He'd have to do.

Vulgaris the Starling Dummy. iPod playing a catbird song in the background.
Once we were set up, it was step back and wait. Our target catbird began singing, and he came in closer to the nets to investigate. Within minutes he swooped over one net, and over the next. Then again. And again. Uh-oh. These nets are kind of hard to see, but it looked like our bird had figured out our ploy and was avoiding them.

Dana and Darrin, dejected. We thought we were in for a long morning.
After about 10 minutes, the catbird flew from behind one net headed back to his usual singing spot and ventured a little too low. Bingo! In the net. We quickly retrieved him.

Joy!

It didn't take long to take him into the banding lab, remove his geolocator and green band (so we didn't go after him again), and take some measurements so we could let him go.

Three happy catbird catchers, and the subject ready to be released.
This catbird, which was carrying geolocator #929, was the last catbird we put a device on last fall, on 29 September 2011. The bird had originally been banded as an adult on 10 August 2010.

The well-traveled geolocator.

Dr. Bowlin is out of state on another field study, and when she returns she will download the data from the device. Then, it will take some additional time to analyze. Sometimes due to weather or time spent in shaded spots by the birds, the data may difficult to interpret. Hopefully, we'll get good data from this bird, as well as any other catbirds that return that we recapture.

And we have already located the favorite singing perch of another color-banded catbird. I hate to report that we have tried catching this bird for several days and have come pretty close, but so far he seems to be on to us and prefers singing about 10 yards from the nets. We also have a tentative sighting of a third bird, and have some areas left to survey for catbird pairs. I'm optimistic we will be able to retrieve a few more geolocators this season.

About half of our catbirds were sponsored by donors last fall. Unfortunately #929 did not have a sponsor, so we didn't get to provide fun news to one of our supporters. If you are interested in sponsoring a catbird with a geolocator, I'll assign one to anybody making a gift of $300 or greater.


Wednesday, May 16, 2012

North American Migration Count 2012

The North American Migration Count takes place the second Saturday each May. It aims to take a "snapshot" of migration, and is compiled on a county basis. My husband Darrin is the coordinator for Wayne County, and as usual we covered the city of Dearborn together on May 12.

Spring migration this year got off to a great start the first week in May. We had very good numbers of early migrants the last week in April into the first week in May. There was a nice influx that included some mid-season migrants on May 3. Within a few days, however, things began to slow down. On migration count day, we tallied a disappointing 70 species on campus. Warblers in particular were very scarce, with only ten species. Yellow-rumped Warblers had been dwindling, but were absent on count day. Many people commented on the high numbers of White-crowned Sparrows this season, but on count day we had only a few, and no White-throated Sparrows. Our best bird on campus was a Gray-cheeked Thrush, the first of the season.

Darrin taking a quick break on campus during the count. Sometimes,
having too few birds is more tiring than having too many!
We added eight more species at other locations in Dearborn. The original Ford "sunflower field" at Hubbard and Southfield had a minimum of two dozen Bobolinks on May 7, but none stuck around for the count.

The Rouge River at Kingfisher Bluff behind Henry Ford
Community College.
Northern Rough-winged Swallows are nesting in the terra cotta
tubes poking out of the bank at Kingfisher Bluff behind Henry
Ford Community College.
The best bird of the day was an Orchard Oriole at Porath (Kielb) Park. This 11-acre property in a sparse residential area adjacent to railyards and an industrial border of Detroit was once a clay mine for bricks. In the 1940s, fill material from construction of I-94 was added. A federal brownfields grant was used to clean up contamination (still no digging allowed, according to warning signs) and it was turned into a park by the city in 2005. There are a variety of native plants there, but aside from a trail that is mowed through it, the park has not been maintained very well and it's becoming weedy and overgrown.

In addition to the oriole, Porath had two very good butterflies. One was a Common Checkered-Skipper (Pyrgus communis), a southern species that has been seen in southern Michigan with increasing frequency the last few years. Not only is this an uncommon species, this is a pretty early date to see them here. It's unlikely that the larvae (the stage in which they hibernate) can survive here overwinter, so the individuals we typically see are migrants from the south, or perhaps some progeny from these migrants which appear later in the season. Their host plants are in the mallow family, and I have seen them most commonly in vacant lots or neglected fields that are infested with velvet-leaf (Abutilon).

Here is my bad documentary photo of a Common Checkered-Skipper at
Porath Park. Click here for a much nicer shot of one in my Dearborn yard last fall.
We also saw another uncommon butterfly, an "Inornate" Common Ringlet (Coenonympha tullia inornata) When we found our first county record in 2003, it represented a substantial southern range expansion in the state (PDF of my note in the newsletter of the Michigan Entomological Society here). This species now shows up all over the place in southern Michigan, moving south here as it has in New England and Ontario in the last decade or so. I failed to get a photo, but here's one Darrin took last fall in Oakland County.


Both the skipper and the ringlet have been observed on the UM-Dearborn campus as well.

A table of results from the Wayne County North American Migration Count, with links to complete results, is available on the RRBO web site. Once we have data from all the other field participants, I'll put up the 2012 results at that location as well.

Thursday, April 26, 2012

Update on European Goldfinches

Update: This paper has been published! It's open access so you can read online or download the PDF; click on title below -

Craves, J.A., and N.M. Anich. 2023. ­­­Status and distribution of an introduced population of European Goldfinches (Carduelis carduelis) in the western Great Lakes region of North America. Neobiota 81:129-155. doi: 10.3897/neobiota.81.97736

--

People continue to leave me comments on my previous posts about European Goldfinches in the U.S. (see list of posts below). I am still keeping track, especially of breeding records. In addition to accumulating reports from proactive observers, I also periodically look through birding listservs and eBird records. Unfortunately, any Illinois records put in eBird are filtered out of public view, but the state reviewer is working on changing this. Even so, I still have over 50 records of well over 100 birds from the past few years just in southern Wisconsin and northern Illinois alone.

Here's a map from a previous post, showing the Wisconsin and Illinois counties highlighted in red where the bulk of reports of European Goldfinch come from.


In a previous post, I documented nesting in Waukegan, Illinois, which is in Lake County. Later, I found a report online of a family of European Goldfinches at Waukegan Beach on 13 August 2009, consisting of five birds: two adults, and two juveniles, with the fifth bird likely also a juvenile. The observer posted this photo on Flickr. The day before the photo was taken, another observer saw a minimum of 13 European Goldfinches foraging in a weedy area in what appeared to be two to four family groups in an area just adjacent to Waukegan Beach.

In 2011, European Goldfinches were reported nest-building at Waukegan Beach. A report in April 2012, just a couple weeks ago, also mentioned them gathering nest material. So it seems a breeding population is well-established in the Waukegan area.

These may not be the first European Goldfinches to have nested in Illinois, as there was also a report of birds nest building at Montrose Point in Chicago, Cook County as early as 2003.

In Wisconsin, the breeding population seems centered in the Racine area of Racine County. That is around 25 miles north of Waukegan. My previous post documented a juvenile in 2009 in the Racine suburb of Mt. Pleasant. Subsequently, I received a report in late July 2009: the Scheefs in suburban Racine reported on a juvenile showing up at their feeders shown in this post.

I also heard from Sarah Anspaugh of Racine, who took the photo below of a European Goldfinch family. A pair showed up at her feeder on 13 May 2009, appeared periodically through June, and on 8 July 8 there were 2 juveniles with them.


Jane Scheef of Racine contacted me again in 2010. The pair in her neighborhood arrived at her feeder on 29 June with 5 young in tow, shown in the photo below.



I think that an eBird report of six to eight coming to a feeder in Racine in late winter 2011 may be the same residence. The largest flock I have heard about was that of 30 on 4 December 2011, also in Racine (I think this checklist is the exact location).

Finally, in between Waukegan, IL and Racine, WI is Kenosha, WI, where a correspondent named Donna has had at least one pair of European Goldfinches at her feeders. In June 2011, she photographed them with three young. She recently wrote me that a pair is currently coming to her feeders.

Unlike American Goldfinches, European Goldfinches typically nest in May and June, so be on the lookout and keep sending those reports.

Here are my other posts:

Sunday, September 13, 2009

How do we know what thrushes are eating?

Last fall, I described the focus of my research: the autumn stopover ecology of migrant thrushes. My paper summarizing weight and fat changes in Hermit, Gray-cheeked (shown above), and Swainson's Thrushes was published earlier this year. This is the third year of building on those results by looking at the specific resources thrushes use here in the fall. Because most migrant birds, including those that typically eat insects, also incorporate fruit into their fall migratory diet, the thrushes make great surrogates for a whole suite of migrant species.

There are lots of fruiting trees, shrubs, and plants on campus. Our banding area, for instance, is located in an area with a high density of Gray Dogwood (Cornus racemosa, below), a native shrub with plentiful white berries.

However, like most urban areas, many of the dominant fruiting plants are from non-native species, such as the Glossy Buckthorn (Frangula alnus) shown below.

As I mentioned previously, some of the questions I seek to answer include which fruiting plants and shrubs commonly found in urban areas -- both native and introduced -- are most important to migratory birds? What is their relative availability? If highly invaded urban natural areas are to undergo restoration efforts, which introduced plants should be left to provide resources for migrant birds while native plants become established?

To find out what the thrushes are eating, we simply collect the droppings they leave in the bags we use to transport the birds from the nets to the banding station. Because fruit passes through birds so quickly (and it is thought that many birds, especially migrants, choose fruit that can be processed quickly and efficiently), we know that whatever they poop out has been eaten on-site. We collect each sample in a plastic bag, labeled with the bird's information.

Later, I sort through and identify all the seeds. I have assembled samples of nearly all the seeds found in fruits growing in the campus natural area (certainly all the common ones). I've also put together a reference book, made up of magnified photos of seeds of dozens of species; these photos are available at the excellent USDA PLANTS database web site. It's actually pretty straightforward. I've had very few seeds I have not been able to identify. I think a lot of them are just malformed seeds of common species. So far, I've collected over 200 seeds from 100 samples from 79 birds (some are from multiple samples from the same bird captured more than once).

In order to determine if resident birds are competing with migrants for the same fruits, or depleting certain fruiting species before migrants arrive, I've started collecting samples from all species of birds, concentrating on American Robins and Gray Catbirds. As we catch WAY more robins and catbirds than thrushes, we will end up with a lot of samples. A UM-D undergraduate and bander, Dana Wloch, will be assisting with the sorting, identification, and compiling of the seed samples as an independent research project this fall. Her time will go to waste, so to speak (sorry, I couldn't resist).

Interested in what I have discovered so far? I'll be presenting an overview of my research and some preliminary seed sampling results at presentations at several bird groups over the winter. The first two are November 2 for Macomb Audubon Society, and November 16 for Grosse Pointe Audubon Society. Check their web sites for locations and times. I'll announce January program dates in a couple months.

Friday, April 3, 2009

Thrush paper published

My paper on the fall stopover ecology of thrushes has finally been published. In addition to all the time it takes to collect data, analyze it, and write a good paper, actually getting it out for all to see is one LONG process! I submitted the paper in April 2008. It went out for peer review, came back to me so that I could respond to questions and comments from the reviewers, and went back to the editors, who approved it in August 2008. Then came the process of checking page proofs for errors and scheduling publication. So at long last, it is in the current issue of the Wilson Journal of Ornithology.

Craves, J. A. 2009. A fifteen-year study of fall stopover patterns of Catharus thrushes at an inland, urban site. Wilson Journal of Ornithology 121:112-118.

You can see the publicly-available abstract and tables at BioOne. I wrote a brief summary of the work last fall here at Net Results.

Wednesday, January 21, 2009

European Goldfinch: established in the U.S.?

Update: This paper has been published! It's open access so you can read online or download the PDF; click on title below -

Craves, J.A., and N.M. Anich. 2023. ­­­Status and distribution of an introduced population of European Goldfinches (Carduelis carduelis) in the western Great Lakes region of North America. Neobiota 81:129-155. doi: 10.3897/neobiota.81.97736



In the fall of 2002, Ford Motor Company planted sunflowers on a 20-acre lot they owned at Hubbard and the Southfield Freeway (M-39) service drive, near their world headquarters. Ford has continued to plant sunflowers, sorghum, and/or a wildflower mix on up to 10 properties scattered across Dearborn. 

The fields have always attracted a lot of birds -- I wrote about the numbers seen on this year's Christmas Bird Count. The very first winter the original field hosted an unusual bird: a European Goldfinch (Carduelis carduelis), a bird not native to North America. European Goldfinches are common in the pet trade, and it's not too unusual to hear about sightings of escaped or released pets. Unlike members of the parrot family, European Goldfinches are very hardy and can survive northern winters. The sighting occurred during a time when I had been hearing more and more reports of European Goldfinch sightings, especially in the Chicago area. Curious, I posted a page on the RRBO web site requesting sightings from the upper Midwest. I also kept my eyes on the various Internet birding lists and regional publications.

That there were a lot of European Goldfinches out there readily became apparent. I compiled over 400 reports, of which 298 were from Illinois, Wisconsin, Indiana, and Michigan. There was a clear concentration in southern Wisconsin and northern Illinois, a pattern of radiation from the "epicenter" that was more pronounced north than south, and a smattering of reports over the rest of the four states.

It is believed that the bulk of these European Goldfinches -- as well as a handful of other European cage bird species that were reported in the same areas -- originated with a bird importer in the greater Chicago area. From a number of independent reports I received, this importer had apparently deliberately released these species on more than one occasion over time. Believe it or not, as long as the birds are legally imported, there is no federal law prohibiting their release, even if they are not native.

Since 2003, there have been reports of nesting European Goldfinches in northern Illinois. They may also be nesting in southern Wisconsin. Great Tits (Parus major), another one of the species involved in the alleged releases, have also nested in southern Wisconsin and northern Illinois! European Goldfinches nest earlier in the year than American Goldfinches and appear to be ecologically benign, although non-native species frequently end up having unanticipated impacts on ecosystems. Whether the breeding population will grow and persist is not known. In the early part of the 20th century, there were a couple of established colonies in New York, founded by deliberate releases. They eventually died out. However, the proliferation of non-native plant species -- many of which are the natural foods of European Goldfinch -- may prove to be a boon for the species this time around.

I don't believe the majority of the Michigan sightings (or the many Ontario reports I've gotten) of European Goldfinches are attributable to same source. The geographic and chronological patterns do not seem to fit. Some are likely just escaped pets. Many others may be deliberately released birds. Some pockets of reports came from areas with higher populations of people that practice eastern religions, which sometimes advocate setting birds free to accrue merit in the afterlife. Employees at my own local pet store, which often carry European Goldfinches for sale, reported to me that these and other cage birds are sometimes purchased by people of various ethnic backgrounds with the intention of releasing them. I presume this is the source of the Dearborn European Goldfinch.

I ended up writing a detailed account of the reports I received, including background on the ecology and history of European Goldfinches in the U.S. and additional information on their future, in a paper that was just published in North American Birds; you can click on the link to download a PDF copy:

Craves, J. A. 2008. Current status of European Goldfinch (Carduelis carduelis) in the western Great Lakes region. North American Birds 62:2-5.


List of updates on this post:

  • June 2009: Nesting European Goldfinch in Illinois.
  • July 2009: Nesting European Goldfinch in Wisconsin.

Photo of European Goldfinch in France by Daniel (ParaScubaSailor) at Flickr under a Creative Commons license.

Tuesday, November 25, 2008

Recovery -- a rare event!

Since not very many banded birds are re-found away from the place they are banded, the majority of what we learn from banding birds comes from data we gather when we band them, and when we recapture birds on site. Nonetheless, every so often we hear about a recovery of one of our banded birds. These reports come from the USGS Bird Banding Lab, which administers bird banding in the U.S. We just got one this week, and it is quite special!

A Northern Waterthrush banded here on campus on 30 April 2007 was recaptured and released at Cedar Grove Ornithological Station in Sheboygan County, Wisconsin on 21 October 2008. The map below shows the location of Cedar Grove with a red marker, and our location in blue (click to enlarge).

How rare is this? Of the 32 recoveries that have been reported to us since 1992, this is only the 14th to have been reported outside the state of Michigan -- you can view an interactive map of all out of state recoveries here. Typically, these birds are found dead. The most common reason, if one is given, is that the bird has been killed by a cat. This waterthrush is just the third bird that has been captured and released by another bander. The others were a Yellow-rumped Warbler we banded in May 1997 that was recaptured in Tallahassee, Florida in March 1998, and a White-throated Sparrow banded in October 1999 that was recaptured on the Bruce Peninsula in Ontario in April 2006 (not a typo!).

But several more factors make the recovery of this waterthrush even more unusual.
  1. The warbler and the sparrow are short-distance migrants, wintering in the U.S. The waterthrush is a long distance migrant. After we banded it, it probably nested in northern Michigan or Canada, then it likely spent the winter somewhere in the West Indies or perhaps Central America (you can view a range map here). Then it went north, nested again, and was headed back south along the western shore of Lake Michigan when it was captured at Cedar Grove.
  2. Cedar Grove is a hawk banding station. For over 50 years, raptors have been banded at Cedar Grove, and small songbirds are only captured incidentally!
  3. I've banded 167 Northern Waterthrushes during spring migrations, but only one has had a bill deformity...this one! So I happened to have photographs of it, which are below.


This slight deformity apparently did not hinder the bird prior to it being banded. It had a lot of fat, and at 22.1 grams, it was the second heaviest waterthrush RRBO has handled in spring, with the average being 18.0 grams.

Update: I've heard from one of the banders in charge at Cedar Grove. He told me that because they do not really "process" songbirds, the waterthrush was not checked for fat or weighed, nor was any abnormality noted. Bummer. I've caught only a few birds banded by other people (the last one was a Ruby-crowed Kinglet in 2005), but -- perhaps because I'm so astonished that it happens at all -- I give them a really thorough going-over.

Most banded birds are found not by other banders, but by regular folks. Here's what you should do if you find a banded bird.

Tuesday, September 9, 2008

Bill deformities and tumors


The other day I banded this HY (hatching-year) cardinal with a bill tumor. It looks sort of like a scab or blob of gunk stuck on the bill, but it's actually growing out of the tissue near the base of the bill. The dark coloration of the rest of the bill is normal: young cardinals have dusky-colored bills well into fall. It's one of the easiest ways to tell a juvenile from an adult.

Bill tumors and other deformities are not terribly uncommon. They often are seen on young birds, probably because many of the deformities ultimately impact survival. Most tumors I have seen have been due to a virus called avian pox. As I wrote on the RRBO bill tumor page, avian pox most frequently causes lesions on the feet and legs of birds, but also affects other soft parts. Pox lesions are scabby, crusty, or warty growths. If near the nostril they can obstruct breathing, or can obstruct vision if near the eyes. The lesions fall off after about a month when the virus runs its course, but it appears they can sometimes compromise the bill structure -- some post-pox birds have chunks of bill missing. This may not be due to the pox itself, but might be due to secondary infections of the pox lesions. Pox can be spread by mosquitoes, or contact between birds (thus it can be spread at feeding stations).

The tumor on the cardinal does not appear to be due to pox, as it actually seems to be growing out of the horny structure of the bill versus "on top," which is how pox often presents. I don't think this tumor is life-threatening in any way, if it doesn't continue to grow. The inside of the bill and mouth are okay, it doesn't look like it will interfere with feeding or grooming, and the nostril is open.

Bill deformities such as crossed bills are a whole other matter. Many years ago, upon capturing a catbird with a crossed bill, I did some research, and ended up publishing a paper on the incidence of bill deformities in passerine birds (songbirds) in North American Bird Bander. Since then, I have kept a compilation of these kinds of deformities in songbirds on the RRBO web site. Many have been contributions from banders and people who have seen the information on the site (I moderate a group on the photo sharing site Flickr on bill deformities which includes all types of birds, not just songbirds).

It is hard to say whether these types of deformities are increasing, or if awareness is just elevated. However, there is one geographic region where something is definitely going on: the Pacific Northwest and in particular Alaska. The USGS's Alaska Science Center has devoted a section of their web site to these abnormalities, many showing up in chickadees.

The USGS Alaskan researcher, Colleen Handel, cited my paper and the RRBO web site several times in her presentation on "The mystery of the long-beak syndrome" at a recent ornithological conference. Colleen and I have discussed these deformities several times over the years, and are planning on collaborating on a paper next year.

Wednesday, September 3, 2008

The first migrant thrushes

Many new species of migrants are coming through this week. Today I banded the first Swainson's Thrush of the fall season. I am really looking forward to thrush migration this year. The three most common species of migrant thrushes here -- Hermit, Gray-cheeked, and Swainson's -- are the subjects of a major paper I recently had accepted to the peer-reviewed Wilson Journal of Ornithology:

Craves, J. A. 2009. A fifteen-year study of fall stopover patterns of Catharus thrushes at an inland, urban site. Wilson Journal of Ornithology 121:112-118.

I analyzed weight and fat data for over 2,000 individual thrushes banded here at RRBO during the fall seasons 1992 to 2006. I used both a regression analysis for all initial captures, and recapture data to examine weight and fat changes in these birds as they used our site as a migratory stopover.

In the paper, I present and discuss a number of different findings. Among them, the majority of individuals of all three species gained significant fat and weight during their stopover on campus. This is especially important because in an urban site such as this one, migrant birds are faced with unique challenges, including a high level of human disturbance which may decrease foraging opportunities, and a preponderance of non-native fruits.

These thrushes rely heavily on fruit during fall migration. Much of the native fruit, to which they are evolutionarily adapted, has been depleted by other species by the time the bulk of the thrushes move through, in particular Hermit Thrushes, which are late migrants. The remaining fruits are predominantly introduced, invasive species such as buckthorn and honeysuckle.

My findings have conservation and management implications. It suggests that thrushes are in fact able to find sufficient resources in urban natural areas similar to our site. Since thrushes gain mass on a diet high in non-native fruits, it demonstrates that some introduced plants do perform ecological functions.

The next question are which fruiting plants and shrubs commonly found in urban areas -- both native and introduced -- are most important to migratory birds? What is their relative availability? If highly invaded urban natural areas are to undergo restoration efforts, which introduced plants should be left to provide resources for migrant birds while native plants become established? In a future post, I'll talk about exactly how we intend to shed some light on those questions with ongoing research!

The vast majority of published papers on stopover ecology have focused on coastal or rural sites, and frequently cover a study period of only 2 or 3 years -- the length of time a graduate student takes to complete a degree. RRBO's work is unique with its focus on an urban, inland site, and especially its long-term nature. It's not enough to catch some birds and see that they've gained some weight between captures. There are many pitfalls in designing studies and gathering data that can be used to draw statistically and biologically significant conclusions. Large data sets are needed to account for many extrinsic variables (such as weather) and weed out ambiguous or problematic data points. I have raw data for a suite of other species besides the thrushes. At some point, they will also be run through the analytical mill, but first I'll be concentrating on the thrush and fruit connection. Stay tuned!