RRBO has closed, but I am still working on several RRBO-related projects, as well as continuing to do urban ecology research independently and providing expertise and service to the scientific community. So whether you are interested in Dearborn and southeast Michigan birds; urban ecology with a focus on birds, insects, and plants in the Midwest; and/or similar endeavors, I hope you continue to follow along here!
Here are some updates:
First, I was asked to work on helping finish a really interesting bird conservation project by the U.S. Fish and Wildlife Service. My involvement was just about squared away when the government shutdown occurred. While I'm pretty sure the project will be completed one day, I have no idea when or how this will happen until after the government reopens, the people involved catch up on their work, and how their budgets shake out.
Meanwhile, I am in the process of bringing the Dearborn bird checklist up to date. There have
been some taxonomy changes, and I will move any material from the RRBO
website on rare or interesting birds here to Net Results, link to
those items on the checklist, and publish it here. I've also been working on a substantially revised annotated checklist. More on that soon.
In April 2019, hosting for the RRBO website will be up for renewal. I pay for this hosting myself, and therefore I'm going to let it lapse. At that time, the RRBO website will be no more, and the URL will point here. I have been and will be moving some material over here to the blog, including the entire section on European cage birds that have become established in the western Great Lakes. This is research I'm continuing, and I plan on publishing another paper. I'll be posting this section shortly.
Recently, a new paper came out that drew upon data I provided. "Species interactions limit the occurrence of urban-adapted birds in cities" was published in the journal PNAS (Proceedings of the National Academy of Sciences of the United States). You can read a news story about it here. I have always strongly believed in sharing data, so even when I have not had the chance to use it in my own publications, I've been happy to contribute to the projects of others.
Finally, I also still post pretty regularly to the RRBO Facebook page, so feel free to engage there.
Thursday, January 24, 2019
Friday, August 31, 2018
RRBO is closing
Due to a lack of sustainable funding, the Rouge River Bird Observatory will cease operations in October 2018. I will be leaving the University as a retiree with Visiting Scholar status, and hope to finish publishing RRBO-related research. I will continue to maintain this blog, and social media (Facebook) for the time being, and I'll use these venues to post updates on publications and related news, for those interested.
I will still be collecting data on European Goldfinches! Please see this page on how to submit data.
Finally, I sincerely thank everyone who supported RRBO in so many ways the past 26 years.
--- Julie Craves
I will still be collecting data on European Goldfinches! Please see this page on how to submit data.
Finally, I sincerely thank everyone who supported RRBO in so many ways the past 26 years.
--- Julie Craves
Thursday, September 7, 2017
New major paper published
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
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.
Saturday, July 1, 2017
Odd plumages and abnormal feather growth
Birds with abberant plumage are one of the more common oddities we see at the Rouge River Bird Observatory. Abnormally-colored feathers are fairly frequent, and some examples are below. One example has its own page: a stunning white-breasted American Robin.
Once or twice a year, we see an American Robin (Turdus migratorius) that has several white feathers or patches of white feathers. This one was photographed by Darrin O'Brien on 29 Apr 2009 at a Dearborn office complex.
This unusual American Robin was banded on 7 Oct 2007. It was an adult female undergoing its fall molt. The breast feathers were normal. However, nearly all of the incoming feathers on the wings, tail, and body that are gray in normal robins were full or partially "frosty" looking.
Typically when abnormal white feathers are seen on birds, the entire feather is white, as in the first example. Partially white feathers like this are something RRBO encounters only rarely, and not to the extent found on this bird.
The bird was re-sighted the following week.
A leucistic Yellow-rumped "Myrtle" Warbler (Dendroica coronata) was found at the on campus from 15 to 17 May 1997. The wings and tail of this bird were entirely white. Soft yellow was visible where most yellow-rumps have bold yellow on the flanks. The back and head were pale gray, and some pale gray streaking replaced the prominent streaking of normal-plumaged yellow-rumps. This bird appeared to be a male. While relatively common in some families of birds, abnormally pigmented individuals are rare in the Parulidae (wood warblers).
This sighting was documented in the following paper:
Craves, J. A. 1997. Extreme leucism in a Yellow-rumped Warbler (Dendroica coronata coronata). Michigan Birds and Natural History 4:199-200.
Carotenoids are the pigments responsible for most of the red and yellow colors in birds. They cannot be created by birds without dietary input. Thus, the pigments in what birds eat can influence the color of their feathers. If a bird consumes particular deep red pigments while feathers are in active growth and also has yellow plumage, some or all of the yellow feathers may turn out to be orange. This is most frequently seen in the terminal tail bands of Cedar Waxwings (Bombycilla cedrorum), which are normally yellow. About 5% of the Cedar Waxwings banded by RRBO have had orange terminal tail bands (right). It was first noticed in the 1960s, and it has since been confirmed that it is due to waxwings consuming the fruit of introduced Morrow's Honeysuckle (Lonicera morrowii), which contains a red pigment called rhodoxanthin. This honeysuckle is common at UM-Dearborn.
A number of other bird species have been recorded with orange or reddish feathers in place of yellow feathers that could be attributable to ingestion of rhodoxanthin. The White-throated Sparrow (Zonotrichia albicollis) at right was banded by RRBO on 27
September 1998. This bird has orange-colored lores rather than yellow.
Subsequently, RRBO has banded two more White-throated Sparrows with
orange lores, and this phenomena has also been reported by other
banders.
The first record was documented in the following paper:
Craves, J. A. 1999. White-throated Sparrow with orange lores. Michigan Birds and Natural History 6:83-84.
Further reading:
Tricks Exotic Shrubs Do: When Baltimore Orioles Stop Being Orange (pdf) by Tom Flinn, Jocelyn Hudon, and Dan Derbyshire -- article from Birding magazine.
Diet explains red flight feathers in Yellow-shafted Flickers in eastern North America. Hudon, J., R.J. Driver, N.H. Rice, T.L. Lloyd-Evans, J.A. Craves, and D.P. Shustak. 2017. The Auk: Ornithological Advances 134:22-33.
Occasionally we have encountered Northern Cardinals (Cardinalis cardinalis) that are very vividly colored or with some orange plumage. The male on the right was banded by RRBO on 25 October 2000. It had patches of orange feathers, and several wing feathers that were orange. This abnormality may have been caused by a lack of some sort of dietary pigment that left the normally red feathers less intensely red. Dietary deficiency of certain carotenoids is responsible for orange- or yellow-colored House Finches (Carpodacus mexicanus).
Perhaps some lack in the diet combined with ingestion of a red pigment like rhodoxanthin that contributed to the orange color as well as the crimson color of the red plumage. Other orange cardinals have turned up in the literature and on the
Internet, beginning in the late 1990s, lending some credence to the role
of honeysuckles and rhodoxanthin in this plumage variation.
Further reading:
An 'orange variant' Northern Cardinal. (pdf) Hansrote, C. and M. 2000. North American Bird Bander 25:1-3.
And now, a white/pink cardinal! Ohio Birds and Biodiversity.
The yellow cardinal lives on. Ohio Birds and Biodiversity.
RRBO has banded a half-dozen Ruby-crowned Kinglets (Regulus calendula) with at least some orange crown feathers rather than salmon red, all since the year 2000. Examples of two individuals are shown below. This may also be due to a dietary deficiency.
The first secondary feather on one wing of this American Goldfinch (Spinus tristus), banded 20 Aug 2010 was completely black on the underside, rather than having a white base. When melanism occurs, it seems that it typically affects all feathers. RRBO has not documented a single melanistic feather or patches of melanistic feathers on any birds, much less the thousands of goldfinches banded on campus.
More information on abnormal plumage coloration
Davis, J. N. 2007. Color abnormalities in birds: A proposed nomenclature for birders. Birding 39:36–46.
David Sibley's web site: Abnormal coloration in birds: Melanin reduction.
British Trust for Ornithology's Abnormal Plumage Survey page.
The first was a young House Wren (Troglodytes aedon) banded on 1 Oct 2003. The tips of 5 tail feathers (rectrices, or “rects”) had unusual, spatulate tips which extended about 5 mm past the “normal” ends of the feathers.
The extensions did not appear to be formed by the wearing away of some of the feather barbs. This was the first time RRBO had ever seen a bird with a tail like this.
On 25 Aug 2008, a young Carolina Wren (Thryothorus ludovicianus) was captured that had a similar tail. This bird only had the odd paddle-like extension on the central tail feather. We recaptured this bird several times that season, and this feather was present each time.
On 5 October 2008, we banded a White-throated Sparrow (Zonotrichia albicollis). One central tail feather was around 10 mm longer than the other feathers. All the rects were fully grown in, so it wasn’t a case of the other feathers having not reached their full length.
Finally, there was the recent capture of a similar case. This adult Cedar Waxwing (Bombycilla cedrorum) also had two extra-long central tail feathers. As with the White-throated Sparrow above, all the feathers were fully grown. It was banded on 8 November 2011.
Plumage that is abnormally white
An an abnormal reduction in the deposition of pigment in the feathers is known as leucism. Some leucistic birds appear entirely washed out or pale if the reduction of pigment is roughly equal in all feathers (some authors now call this “hypomelanism”). More often, pigment is absent in only some feathers, and this is known as pied leucism, or “partial amelanism.” Causes include genetics, or injury, disease, or malnutrition.This unusual American Robin was banded on 7 Oct 2007. It was an adult female undergoing its fall molt. The breast feathers were normal. However, nearly all of the incoming feathers on the wings, tail, and body that are gray in normal robins were full or partially "frosty" looking.
Typically when abnormal white feathers are seen on birds, the entire feather is white, as in the first example. Partially white feathers like this are something RRBO encounters only rarely, and not to the extent found on this bird.
The bird was re-sighted the following week.Plumage that is abnormally orange
Further reading:
Tricks Exotic Shrubs Do: When Baltimore Orioles Stop Being Orange (pdf) by Tom Flinn, Jocelyn Hudon, and Dan Derbyshire -- article from Birding magazine.
Diet explains red flight feathers in Yellow-shafted Flickers in eastern North America. Hudon, J., R.J. Driver, N.H. Rice, T.L. Lloyd-Evans, J.A. Craves, and D.P. Shustak. 2017. The Auk: Ornithological Advances 134:22-33.
Further reading: An 'orange variant' Northern Cardinal. (pdf) Hansrote, C. and M. 2000. North American Bird Bander 25:1-3.
And now, a white/pink cardinal! Ohio Birds and Biodiversity.
The yellow cardinal lives on. Ohio Birds and Biodiversity.
RRBO has banded a half-dozen Ruby-crowned Kinglets (Regulus calendula) with at least some orange crown feathers rather than salmon red, all since the year 2000. Examples of two individuals are shown below. This may also be due to a dietary deficiency.
Abnormally dark plumage
When birds have plumage with excess pigment, usually the dark melanin pigments, they are known as melanistic. This Mourning Dove (Zenaida macroura) was seen in the Dearborn yard of Julie Craves and Darrin O'Brien on 8 Apr 2006. The second photo shows it compared to a normally-colored Mourning Dove.
The first secondary feather on one wing of this American Goldfinch (Spinus tristus), banded 20 Aug 2010 was completely black on the underside, rather than having a white base. When melanism occurs, it seems that it typically affects all feathers. RRBO has not documented a single melanistic feather or patches of melanistic feathers on any birds, much less the thousands of goldfinches banded on campus.
More information on abnormal plumage coloration
Davis, J. N. 2007. Color abnormalities in birds: A proposed nomenclature for birders. Birding 39:36–46.
David Sibley's web site: Abnormal coloration in birds: Melanin reduction.
British Trust for Ornithology's Abnormal Plumage Survey page.
Abnormal feather growth
On several occasions, the Rouge River Bird Observatory has banded a bird that had an unusual tail.
See more weird birds:
- Strange looking birds -- Cornell's Project FeederWatch
- Atypical birds photo gallery at BirdWatching Magazine
- Miscolored birds Flickr photo pool (no longer moderated, so not all birds are valid examples)
Friday, April 21, 2017
Winter Bird Population Survey 2016-2017
The 25th year of RRBO's Winter Bird Population Survey was completed in February.
It was another mild winter. It began rather snowy with temperatures close to average, but January and February saw less snow and temperatures well above normal. Surveys were conducted on 16 days (previous mean 14) with 26.5 hours total (mean is 27.7). For the third year, I was unable to survey anywhere along the Rouge River from Fair Lane Estate south due to it being fenced off for riverbank restoration.
A total of 41 species was two above the previous 24-year mean. Two new species for the survey were recorded: Field Sparrow and the female Pileated Woodpecker that has been present on campus since fall. These bring the cumulative total for the survey to 79 species.
Fruit-eating birds were scarce again. Robins were in low numbers. No Hermit Thrushes, Cedar Waxwings, or Yellow-rumped Warblers were recorded. These latter 3 species have become more and more scarce the last 5 or so years. Because they typically occur in fairly low numbers, I have not yet worked with their data. But the trends with robins might shed some light (see below).
Now that we are at the 25 year mark, I thought I would provide a little summary data and analysis.
Twenty species have been found every year: Canada Goose, Mallard, Red-tailed Hawk, Mourning Dove, Red-bellied Woodpecker, Downy Woodpecker, Hairy Woodpecker, Blue Jay, American Crow, Black-capped Chickadee, White-breasted Nuthatch, Brown Creeper, American Robin, European Starling, American Tree Sparrow, Dark-eyed Junco, Northern Cardinal, House Finch, American Goldfinch, and House Sparrow. Five more were found on 24 counts: Cooper's Hawk, Ring-billed Gull, Tufted Titmouse, Carolina Wren, and Song Sparrow. These 25 species can be considered our core winter residents.
About a third of the species have only been recorded one or two years, and can be considered rarities in winter. Some of the more interesting ones include Northern Shrike (winter 1995-96), Long-eared Owl (2009-10), Rough-legged Hawk (1994-95), and White-winged Crossbill (2008-09).
Population trends take a little more time to work through, so I just did some quick calculations on common species to see if anything popped out. Not much obvious was apparent for most species using the limited analysis* performed. Perhaps the most interesting were the trends for the two most abundant fruit eaters, American Robin and European Starling.
Both species for many years were more or less stable, with increases starting around ten years ago. I suspect this would correlate with increasing average winter temperatures and decreasing snow cover, but I have not yet incorporated weather data into my analyses. Around 2010 (vertical line on graph) both species being to show declines. This was approximately the time when large-scale removal of invasive fruiting tree and shrubs began, which both bird species heavily utilize in winter. This may indicate a pitfall of removing an important food source without concurrent restoration. Indeed, an examination of robin fecal samples from 2009 through 2017 shows a 52% decrease in the proportion of samples containing non-native Common Buckthorn (Rhamnus cathartica) seeds, the first primary target of the eradication effort. A closer look at the fecal samples reveals another unfortunate result of removing a food source without replacing it with something more desirable.
Non-native Callery or Bradford Pear (Pyrus calleryana) and Border Privet (Ligustrum obtusifolium) have become naturalized on campus. Their seeds did not appear in fecal samples until 2013, but have been increasing every year since. These species are generally not favored by birds -- pear fruits are fairly large and mealy, while privets are dry and have large seeds and little pulp. These percentages are modest, but bear in mind that the vast majority of plant species are found in less than 3% of samples; samples are dominated by buckthorn, non-native crabapples, and non-native honeysuckles. The third species in the chart is non-native Oriental Bittersweet (Celastrus orbiculatus). While there is some native American Bittersweet (Celastrus scandens) here, Oriental Bittersweet is far more common. Birds seem to favor Oriental Bittersweet, perhaps because it has slightly smaller fruit and smaller seeds. Seeds of bittersweet have have greatly increased. Robins, at least, appear to be turning to alternative fruits, those that are less desirable or not as common as what has been removed. This creates an undesirable feedback loop: increased consumption will also lead to increased dispersal of these species.
One other bird species appeared to respond to the habitat changes that started in 2010.
Mourning Doves may be increasing due to the substantial clearing of the understory.
Over the past 25 years, two other events had an influence on bird population. One was the arrival of West Nile Virus in 2001 (vertical line in graph below). I have shown the dramatic decline in American Crows before, and they have yet to recover.
Blue Jays are related and also known to have been impacted by the virus. Their populations appear to have rebounded nicely.
Finally, the Emerald Ash Borer was detected here around 2002, and all our ash trees died within a few years.
While the modest increases might be due to extra food for woodpeckers in dead and dying trees, I don't think the data here indicate that the beetles had much of an effect on woodpecker populations. It might be due to methodology, but since "housing" is often the limiting factor for cavity nesters and the ash trees tended to fall over shortly after death and therefore did not supply more cavities, I think the overall impact on woodpecker numbers was modest.
*Notes on methods: I looked at species seen every year that had an average of 5 or more individuals seen per survey day; I excluded waterfowl and added American Crow and Red-bellied Woodpecker. I used birds per survey day rather than raw numbers or hours because for most species that provided the strongest correlation. To smooth out data I used a 3-year moving average, which is why the graphs begin in 1996 rather than 1993. When I work on a full analysis, I will be more thorough and provide more details on methods, but for the purposes of this post, these methods should suffice.
It was another mild winter. It began rather snowy with temperatures close to average, but January and February saw less snow and temperatures well above normal. Surveys were conducted on 16 days (previous mean 14) with 26.5 hours total (mean is 27.7). For the third year, I was unable to survey anywhere along the Rouge River from Fair Lane Estate south due to it being fenced off for riverbank restoration.
A total of 41 species was two above the previous 24-year mean. Two new species for the survey were recorded: Field Sparrow and the female Pileated Woodpecker that has been present on campus since fall. These bring the cumulative total for the survey to 79 species.
Fruit-eating birds were scarce again. Robins were in low numbers. No Hermit Thrushes, Cedar Waxwings, or Yellow-rumped Warblers were recorded. These latter 3 species have become more and more scarce the last 5 or so years. Because they typically occur in fairly low numbers, I have not yet worked with their data. But the trends with robins might shed some light (see below).
Now that we are at the 25 year mark, I thought I would provide a little summary data and analysis.
Twenty species have been found every year: Canada Goose, Mallard, Red-tailed Hawk, Mourning Dove, Red-bellied Woodpecker, Downy Woodpecker, Hairy Woodpecker, Blue Jay, American Crow, Black-capped Chickadee, White-breasted Nuthatch, Brown Creeper, American Robin, European Starling, American Tree Sparrow, Dark-eyed Junco, Northern Cardinal, House Finch, American Goldfinch, and House Sparrow. Five more were found on 24 counts: Cooper's Hawk, Ring-billed Gull, Tufted Titmouse, Carolina Wren, and Song Sparrow. These 25 species can be considered our core winter residents.
About a third of the species have only been recorded one or two years, and can be considered rarities in winter. Some of the more interesting ones include Northern Shrike (winter 1995-96), Long-eared Owl (2009-10), Rough-legged Hawk (1994-95), and White-winged Crossbill (2008-09).
Population trends take a little more time to work through, so I just did some quick calculations on common species to see if anything popped out. Not much obvious was apparent for most species using the limited analysis* performed. Perhaps the most interesting were the trends for the two most abundant fruit eaters, American Robin and European Starling.
Both species for many years were more or less stable, with increases starting around ten years ago. I suspect this would correlate with increasing average winter temperatures and decreasing snow cover, but I have not yet incorporated weather data into my analyses. Around 2010 (vertical line on graph) both species being to show declines. This was approximately the time when large-scale removal of invasive fruiting tree and shrubs began, which both bird species heavily utilize in winter. This may indicate a pitfall of removing an important food source without concurrent restoration. Indeed, an examination of robin fecal samples from 2009 through 2017 shows a 52% decrease in the proportion of samples containing non-native Common Buckthorn (Rhamnus cathartica) seeds, the first primary target of the eradication effort. A closer look at the fecal samples reveals another unfortunate result of removing a food source without replacing it with something more desirable.
Non-native Callery or Bradford Pear (Pyrus calleryana) and Border Privet (Ligustrum obtusifolium) have become naturalized on campus. Their seeds did not appear in fecal samples until 2013, but have been increasing every year since. These species are generally not favored by birds -- pear fruits are fairly large and mealy, while privets are dry and have large seeds and little pulp. These percentages are modest, but bear in mind that the vast majority of plant species are found in less than 3% of samples; samples are dominated by buckthorn, non-native crabapples, and non-native honeysuckles. The third species in the chart is non-native Oriental Bittersweet (Celastrus orbiculatus). While there is some native American Bittersweet (Celastrus scandens) here, Oriental Bittersweet is far more common. Birds seem to favor Oriental Bittersweet, perhaps because it has slightly smaller fruit and smaller seeds. Seeds of bittersweet have have greatly increased. Robins, at least, appear to be turning to alternative fruits, those that are less desirable or not as common as what has been removed. This creates an undesirable feedback loop: increased consumption will also lead to increased dispersal of these species.
One other bird species appeared to respond to the habitat changes that started in 2010.
Mourning Doves may be increasing due to the substantial clearing of the understory.
Over the past 25 years, two other events had an influence on bird population. One was the arrival of West Nile Virus in 2001 (vertical line in graph below). I have shown the dramatic decline in American Crows before, and they have yet to recover.
Blue Jays are related and also known to have been impacted by the virus. Their populations appear to have rebounded nicely.
Finally, the Emerald Ash Borer was detected here around 2002, and all our ash trees died within a few years.
While the modest increases might be due to extra food for woodpeckers in dead and dying trees, I don't think the data here indicate that the beetles had much of an effect on woodpecker populations. It might be due to methodology, but since "housing" is often the limiting factor for cavity nesters and the ash trees tended to fall over shortly after death and therefore did not supply more cavities, I think the overall impact on woodpecker numbers was modest.
*Notes on methods: I looked at species seen every year that had an average of 5 or more individuals seen per survey day; I excluded waterfowl and added American Crow and Red-bellied Woodpecker. I used birds per survey day rather than raw numbers or hours because for most species that provided the strongest correlation. To smooth out data I used a 3-year moving average, which is why the graphs begin in 1996 rather than 1993. When I work on a full analysis, I will be more thorough and provide more details on methods, but for the purposes of this post, these methods should suffice.
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