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.
Monday, February 29, 2016
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.
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.
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.
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 books 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!
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 books 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!
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