Thursday, March 23, 2017

The forgotten Detroit River Ivory Gull

Over the years, the University of Michigan-Dearborn has hosted its fair share of rare birds, including the first state record of Virginia's Warbler. Earlier this month, the University's Flint campus had its turn, hosting an Ivory Gull, a charismatic and beautiful high-Arctic bird that was a life bird for many that saw it. Sadly, it was found dead a few days after its discovery -- a good article about the bird can be found here. That article notes that this bird was the second Ivory Gull "on record" for Michigan. It's true that this is a remarkably rare bird in the United States, and Michigan. There have been, however, multiple reports in the state.

As far as I know, the first documented Ivory Gull in Michigan was an immature bird seen on the Detroit River between Grosse Ile and Trenton on 12 January 1949. This short note was published in Michigan Audubon's The Jack-Pine Warbler (Vol. 27, No. 2) in 1949.

A little more on these observers: Laurel (not Lauren) Van Camp was a game warden for Ottawa County, Ohio (later with the Ohio Department of Natural Resources), a prolific conservation writer and bird bander, and the man who laid out the trails at what is now the Magee Marsh Bird Trail (read more in this piece from the Black Swamp Bird Observatory). Morgan Wilson and Fred Brint were both with the U.S. Fish and Wildlife Service and worked in game management and Migratory Bird Treaty enforcement. John Anderson was a waterfowl and wildlife biologist and manager of the Winous Point Shooting Club in Port Clinton, Ohio. These were all professional biologists that specialized in waterfowl and thus also likely to be well-versed in gulls and other waterbirds.

At that time (of landline telephones and bulky, expensive film cameras) there was no formal avenue or protocol to report interesting birds. A regular record of birds was published in the Jack-Pine Warbler in its seasonal survey, and more compelling birds were written up and published, as above.

Nearly 40 years later, an organization of birders was formed to maintain the official state bird checklist, including by determining the acceptability of sightings of birds unusual to the state. Soon after its formation in 1988, the Michigan Bird Records Committee began reviewing historical records. Initially, all first state records had to be accepted by a unanimous vote. The Detroit River Ivory Gull was "not accepted" due to a 6-1 vote; the write up from the 1990-91 annual report is below:

In 1999, the Committee rules changed, and first state records could be accepted under same standards as other records (a vote of 7-0 or 6-1 in the first round of voting, or 5-2 or 4-3 in a resubmitted round). The Detroit River Ivory Gull status did not automatically change, although the original vote was 6-1. The record was re-evaluated and voted on again, and fared even worse than before, with 4 votes not to "accept." Here is the 1999 annual report:

Personally, although I have done quite a few winter waterfowl counts along this very stretch of the river, I have never seen a Rock Dove (pigeon) out on the river with gulls and ducks. Less unusual would be a white Rock Dove, but I can't say I have seen too many in my 30+ years of urban birding, and none with black legs as described (Rock Doves nearly always have pink legs and feet).

When Ivory Gulls are seen in the U.S. or southern Canada, it is not uncommon for several birds to be present, or for one bird to range widely throughout a region over the season*. On 1 January 1949, less than two weeks before the Detroit River sighting, an Ivory Gull was reported from Lake Michigan's Waukegan Harbor. The Illinois records committee report, published in 2003:

And just prior to that, from 28-31 December 1948, an immature Ivory Gull was present in at Port Burwell on Lake Erie, Ontario.

To my knowledge, the Detroit River Ivory Gull is the first report of this species in Michigan, and the only record from Wayne County.

*This winter, an Ivory Gull was seen on 29 December 2016 outside Columbus, Ohio, and another on 3 March 2017 in Colchester, Ontario; some people speculated the latter bird was the same one that showed up in Flint.

Friday, January 6, 2017

Dearborn portion of the Detroit River Christmas Bird Count 2017

The Detroit River Michigan-Ontario Christmas Bird Count was held, as it is each year, on January 1. This was the 40th year for the count, which is centered at I-94 and Warren Ave, and the 23rd year that RRBO has coordinated the field work in the city of Dearborn.

After a warm and late fall, the area experienced both a couple of very cold spells and one deep snow. All was gone by count day, however, and the weather was the most pleasant January 1 we have experienced in a long time. Flowing water was open, so waterfowl was not only not concentrated, but apparently largely elsewhere.  The Rouge River at the Ford Rouge complex usually has a decent variety of diving ducks, they were absent for the second winter in a row.  The complex is also an unusual but annual wintering spot for Black-crowned Night-herons. Only one was in the usual spot, with eight others along the river's open waters instead. This was a low number, as there are usually around 20 or so in this location.

As is often the case, gulls were the story at the Rouge Plant. This year, a first winter Iceland Gull was a first for the Dearborn portion of the count, and a first record for Dearborn. This brings the Dearborn bird checklist to 264 species. The bird was found by the crew that has permission to bird in the plant: Mike O'Leary, Jim Fowler, and Dave Washington. Photos below by Mike and Dave.

Campus was well covered, and a Pileated Woodpecker that has been present in the area since fall was located -- not only the first recorded on the Dearborn portion of the count, but the first for the entire 40-year history of the Detroit River count.

Counters were prevented from covering the south end of campus controlled by Fairlane Estate, so a large portion of the open river and riparian areas were not covered.

A number of the Ford sunflower fields were either mowed or being used for construction. Two others were briefly covered. This is the first year Cooper’s Hawk was missed on count day in 21 years, and the first year since 2010 Peregrine was missed; lack of habitat for prey birds around the Ford headquarters was no doubt a factor.

The number of American Robins was the lowest since 1999. Eight American Crows was a comeback of sorts, as they were missed the last two years; there have been more than 8 crows only once in the last 13 years.

The most interesting non-bird observation of the day were the trees along the Rouge River across from the Dearborn Country Club that were being girdled by beavers. The largest tree was about 12 inches in diameter.

Older work.
Recent munching.
Very fresh tooth marks.
We ended the day with 41 bird species. The two new additions bring the cumulative total for the Dearborn portion of the count to 90 species. 

Monday, February 29, 2016

Winter Bird Population Survey 2015-2016

The 24th year of RRBO's Winter Bird Population Survey has been completed.

After two brutally cold winters, this one was much milder, less snowy, and generally more pleasant. Surveys were conducted on 13 days (one day fewer than the mean) and a little over 20 hours total (lower than the mean of 28). Access restrictions continued this year. I was unable to survey anywhere along the Rouge River from Fair Lane Estate south due to it being fenced off for continued riverbank restoration. Thus, no Belted Kingfishers or Rock Pigeons were recorded (for the latter, the first time in 24 years). Only a few herons, and not many waterfowl were counted. Heavy construction activity continued along Fair Lane Drive for the new science building, impacting bird activity along eastern edge of survey area.
Nonetheless, the 38 species tallied was right on average. Two new species for the survey were recorded: Sandhill Crane and Wood Duck. These early migrants came at the very end of the season following a very warm weekend with southerly winds. These bring the cumulative total for the survey to 77 species.

Other uncommon species included a Bald Eagle; this adult bird was first seen in late December and continued to be spotted throughout the count period along the Rouge River (mostly on the south end of campus and along the concrete channel) but was only seen on one survey day. Although eagles are almost annual here, it was only the second time one has been recorded on this survey. A (singing!) Fox Sparrow early in the survey period was the third recorded for the survey. One or two American Crows were found on 4 survey dates. These birds were at the far north end of the campus.

At the other end of the spectrum, 7 species were found on all 13 survey days. In descending order of abundance they were: House Sparrow, House Finch, Northern Cardinal, Blue Jay, Black-capped Chickadee, Downy Woodpecker, and White-breasted Nuthatch -- all feeder birds. House Finches and House Sparrows were recorded in numbers well above average. For House Finches it was a record year, with a 127% increase from average.

Once again fruit-eating birds were largely absent. Three Cedar Waxwings on the first survey day were the only ones of the season. No Hermit Thrushes or Yellow-rumped Warblers were recorded. American Robins were counted, when present, in single digits most of the period. Last year robins were generally scarce on regional winter bird counts. This winter numbers of robins reported to eBird in southeast Michigan were much higher than last winter.  This suggests that the removal of fruit-bearing non-native trees and shrubs that is being undertaken by the university the past few years has had an impact on these numbers. This seems to be substantiated by data recorded this year showing that only 30% of the robins recorded were in areas where this type of vegetation removal had taken place.

For all the numbers from this year you can visit the RRBO web site. The page includes past counts and the history and methodology of the survey. 

Tuesday, January 12, 2016

Dearborn portion of Detroit River CBC, 2016

The Detroit River Michigan-Ontario Christmas Bird Count was held, as it is each year, on January 1. This was the 38th year for the count, which is centered at I-94 and Warren Ave, and the 22nd year that RRBO has coordinated the field work in the city of Dearborn.

After a record warm December, the new year came in cold (27-35F), breezy, and with snow flurries all day long. Water was still open, so waterfowl was not only not concentrated, but apparently largely elsewhere.  The Rouge River at the Ford Rouge complex usually has a decent variety of diving ducks, but not this year. However, there were two Lesser Black-backed Gulls there; one there last year was the first on the count. Seven Great Black-backed Gulls were also present. This is a pretty average number now for a species that used to be rare in the Great Lakes. The complex is also an unusual but annual wintering spot for Black-crowned Night-herons. There were 22 counted this year, a little above the average of 19.2 for the previous 10 years. Peregrine Falcons have become nearly annual on the Dearborn portion of this count, and this year's was found at the complex as well.

After some issues the last couple of years, personnel was re-jiggered to make sure the UM-D campus habitat was well covered. The snow and wind made small birds hard to find, and in general nothing notable was found. The west side of the river across from campus was also thoroughly searched, and you can read about that section with some great photos of a hybrid Mallard x American Black Duck and robins eating privet at Into the Woods and Elsewhere.

A personal issue sidelined one participant, and left most sunflower/wildflower fields uncounted and some other routes in the city uncovered. Only one major field had standing sunflowers, though, the one in front of Ford World Headquarters at Michigan Avenue and Mercury. It got a quick once-over, and the count’s third Merlin was found there.

Merlin. Photo copyrighted, no use without permission.

Pine Siskins have only been recorded on four counts, so 14 at a west Dearborn feeder was a good find.  An adult Bald Eagle has been seen around the river several times, but didn't show up on count day. It was found on January 2 for a "count week" species. Red-breasted Nuthatches have been very scarce the last couple of winters, but one has been seen regularly in the Springwells Park neighborhood. Unfortunately, it was last seen sometime around Christmas.

Everyone familiar with this count and our winter bird surveys knows that Dearborn has not seen its American Crow population recover since it was decimated by West Nile Virus -- my most recent summary is here. Last year it finally happened: no crows for the first time in the history of the count. This year there were also no crows counted.

We ended the day with 37 pecies, which is a record low. No new species this year keeps the cumulative species count for the Dearborn portion of this CBC at 88.

The complete results of the Dearborn portion of the Detroit River CBC can be found at the RRBO web site, which includes historical results.

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. 

Friday, December 18, 2015


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!