Monday, June 9, 2014

Spring bird survey results

Over the months of April and May, 127 bird species were recorded on campus, bringing the 2014 total to 139 species. For the city of  Dearborn, the 2014 species count is 141. The best day was 8 May with 73 species reported, including 19 warbler species. The previous 5-year average for April-May counts on campus is 131, so this year was only slightly below average. Big misses (excluding several species mentioned in the warbler account below) included Black-billed Cuckoo and Willow Flycatcher. Flycatchers in general have seemed scarcer here in recent years, although this year we had good numbers of Least and Yellow-bellied Flycatchers.

The entire survey season was severely hampered by major construction on campus directly adjacent to the Natural Area. In particular, there was daily jackhammering in the parking structure, which served as a giant amplifier and made hearing anything in the northern half of the area nearly impossible. Fortunately, the prolonged cold of early spring delayed leaf-out, so many birds were easy to see.

It was a good year for warblers. Despite missing Golden-winged Warbler, Orange-crowned Warbler, and Hooded Warbler (which although rare is still recorded almost every year), we recorded 28 species. Highlights included:
Prothonotary Warbler -- A silent individual along Fairlane Lake on 9 May.
Connecticut Warbler -- Singing male 27 May.
Prairie Warbler -- One reported on 10 May.
Yellow-breasted Chat -- One along the south bike path was the first Dearborn record in 8 years.

Other highlights included:
Osprey -- Individuals seen around Fairlane Lake on 18 April and 14 May.
Bald Eagle -- Flyovers on 15 and 17 April were the third and fourth records for campus for the year.
Olive-sided Flycatcher -- One on 28 May by the Fair Lane Estate boathouse.
Acadian Flycatcher -- Singing along Fairlane Drive on 21 May.
Eastern Bluebird -- A male by the EIC on 14 May. 
Summer Tanager -- A male near the EIC on 24 May.
Bobolink -- A male singing high in a tree in the forest adjacent to Fairlane Lake on 28 April tied an early spring date for Dearborn, and was radically out-of-habitat!

An interesting Baltimore Oriole first found by Dr. Orin Gelderloos and his field biology class on May 21 and present through at least the end of the month near the north bridge over the Rouge River, behind Henry Ford College. It had the typical plumage of an older male, except it had no black on the head or face, and just a smattering down the chin and chest. The head color was a glowing golden orange, and the bill color was horn/beige, rather than the usual blue-black. Thus, it apparently had some sort of lack of melanin in the head -- quite stunning and unique!

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 on Tuesday, May 6th from 1 to 2 PM. EST.

Wednesday, February 26, 2014

Winter Bird Population Survey 2013-2014

The 22nd year of RRBO's Winter Bird Population Survey has been completed. Those of you that know me know that I do not like winter. I can't believe I've been doing this for so many years, and the weather this year made it especially difficult, mentally and logistically! This will wind up being the second snowiest winter on record for the Detroit area. There was snow cover the entire late-December to late-February survey period, and walking was often difficult. Worse were the cold temperatures. Despite many days of sub-zero temps or wind chills that at times prevented me from going out, I still got in 15 surveys (the average is 14). On the "bright" side, water was frozen most of the time, and I was able to do the around-the-lake portion of my route on the lake, which was easier to walk on!

This year 42 species were tallied. The previous annual average number of species is 38. Two new species were added this year: Purple Finch and Red-breasted Merganser, bringing the cumulative species total for 22 years to 75. The Purple Finch was seen twice. This is a species that is a fairly common migrant here, but not very frequent in winter and never recorded on a survey day. Thus, it was perhaps and "expected" species.

Much less expected were the Red-breasted Mergansers, which usually overwinter on big water (oceans, large lakes, or in smaller numbers on large rivers). Several were seen with Common Mergansers (and some Common Goldeneyes) in the Rouge River where the lower Rouge enters the main river at the south end of campus. This occurred on the last survey date, after a very long period of cold weather, on the only open water in the vicinity. This was only the second record of Red-breasted Merganser on campus and one of the few Dearborn records outside spring migration. Here is my lousy cell phone photo of an adult male:

The ice cover was responsible for the low numbers of our most common waterfowl over the course of the survey period. Canada Goose and Mallard were each only recorded on one day. Great Blue Herons and Belted Kingfisher were also mostly absent this year.

Last year, Merlin was a new species, and we had another this year, on 10 February.  The falcon was sitting along the river near the waterfall behind Fair Lane Estate, and was spied by an American Crow, the only crow recorded during the survey period. The fiesty Merlin turned the tables on the crow and chased it off. A fun, yet bittersweet, encounter, given the continuing lack of recovery of crow numbers here in Dearborn. This marks the tenth time in the past 12 years when fewer than 10 crows were counted on the survey.

On the other hand, people commented that Blue Jays seemed quite abundant this year, which was confirmed on the survey. Our average is 122 a year, and we had 216 this winter, a record.

After last year's winter finch invasion, we had no Pine Siskins, Common Redpolls, or other species usually included in this group (including Red-breasted Nuthatch). But due to deep snow we did have a lot of seed-eating birds hanging around our organic garden, native gardens, and bird feeding areas. Mourning Doves, White-throated Sparrows, Dark-eyed Juncos, House Finches, and House Sparrows were all counted in above-average numbers.

On the RRBO web site, you can find the full results of all 22 years of surveys, along with information on the protocol.

Friday, January 10, 2014

Dearborn portion of Detroit River CBC, 2014

The Detroit River Michigan-Ontario Christmas Bird Count was held, as it is each year, on January 1. This was the 36th year for the count, which is centered at I-94 and Warren Ave, and the 20th year that RRBO has coordinated the field work in the city of Dearborn.

The weather was probably one of the most miserable we have experienced on a count day. Temperatures did not exceed 11F all day, it was windy, and it snowed continuously. As it had been snowing much of the previous night, roads were slippery and a hazard. While waiting at an intersection at one point, we narrowly missed being hit by a car that could not stop; the car next to us was far less fortunate.

As we expected with the weather, birds were not easy to find. Counting on the west side of the Rouge River opposite the Henry Ford Community College and University of Michigan-Dearborn campuses, Cathy Carroll had the best birds. She had a Yellow-bellied Sapsucker, which has only been found on two previous counts. She also had the only Golden-crowned Kinglets of the day (found on five previous counts), as well as the only Brown Creepers and Northern Flicker. Her best bird was probably this forlorn-looking, snow-covered American Black Duck in the river near Dearborn's Ford Field. This is a species that is getting more and more infrequent in the city.

American Black Duck.
While the weather was a notable cause for a lack of bird numbers, it was not the main culprit. This year the sunflowers on the Ford World Headquarters site were planted late and got caught by a frost while they were still in bloom, so they did not set seed. Last year, this field had thousands of birds, including 3500 House Sparrows. This year, all we had there was a single Northern Cardinal.

Sunflower field with Ford World Headquarters in the background. Inset shows
a frozen sunflower head that did not set seed.
The fields at Hubbard and Southfield have been planted in hay the last few years. Not much going on there, except for nearly 300 Canada Geese hunkered down in the stubble. One of them was familiar, a goose with a neck collar that we first found and reported during winter 2011. She was originally banded as an adult female in August 2002 on Akimiski Island, Nunavut. We used to see a whole flock of birds from this James Bay island in the winter around here, but she appears to be the only one left. Another 400+ geese were in another field at Rotunda and Schaefer, with more at the Ford Rouge Plant. This was the second-highest total of geese we've had on the count since 1999.

Besides the geese, not much in these fields. Our numbers of small songbirds, especially Dark-eyed Junco, House Finch, American Goldfinch, and House Sparrow are at or near record lows due to the lack of seeds in these field. We also usually have a wintering flock of blackbirds in these fields, and this is only the second count since 2003 we have not had any Red-winged Blackbirds.

Although I have not received any recent reports of wintering Peregrine Falcons in this area this season, we did have one fly from the Ford building north across this field in the morning.

The flat-line crow numbers continue, with only a single American Crow counted. We have not counted more than 18 crows on any count day since the West Nile virus hit the area in 2002.

American Robins furnished an interesting story, with a total of 653 being our second highest total in 20 years. As noted in my post regarding our fall banding season, the fruit crop was phenomenal this year, after a near-failure last year due to drought. Robins took full advantage of this and were found feasting on non-native Common Buckthorn and ornamental crabapples in various places throughout the city. In previous counts, about 56% of the robins on average are found on campus, where there they have primarily fed on buckthorn. This year, nearly all of the buckthorn and other non-native fruiting plants have been eradicated in the campus natural area, leaving robins and other fruit-eating birds to forage elsewhere. Only 6% of the robins on this count were found on campus. The only other year when the percentage was below 33% was last year when the drought wiped out the fruit crop; 8% of robins on that count were on campus.

In this region, there are not a huge number native plants with fruit suitable for songbirds that are available in winter. Climbing/Prairie Rose (Rosa setigera), American Bittersweet (Celastrus scandens), and Eastern Red-cedar (Juniperus viriginiana) come to mind. For better or worse, if it were not for generations of widespread planting of non-native fruiting plants, we probably would not have as many overwintering robins.

Oddly enough, we have never had Purple Finch on the count until this year. This is not an uncommon species, but we mainly see them here in fall migration, and they are gone by count day. Rick Simek found this one the previous week on campus, and was able to relocate it for a new count day species. This brings the cumulative number of species to 87 for the Dearborn portion of the count.

We ended the day with 48 pecies, which is two above average.

Wednesday, November 13, 2013

Fall 2013 banding season

(Cross-posted at the RRBO web site)

Our 22nd fall banding season took place on 29 days from 15 August to 5 November. An average of 15 nets (12 meter equivalent*) were open an average of 4.6 hours per day. This is the fewest number of days we have been open in a fall season, although our modified hours were intentional -- we wanted to concentrate on maximizing the data we obtain on the fall diets of migrant birds.

Unfortunately, we also lost a 10-day period while we tried to live trap an abandoned cat that had found its way into our banding area. With the safety of birds coming first, we cannot have our nets open when we know there is a predator in the area. We brought this cat to the local shelter, where they felt it was possible it could be put up for adoption. Sadly, people dump unwanted pets here fairly regularly. This is tragic, as is the toll on wildlife taken by owned cats that are let outdoors. I've said it before, but it bears repeating: please keep your cats indoors!

Unlike some years, we did not lose much time to bad weather. I hesitate to complain, but the weather was almost too nice on banding days! The best banding conditions usually occur on calm, overcast days, often before an approaching weather front. This season, over 80% of the banding days were clear or mostly sunny.

Fall banding numbers often also have a lot to do with weather in the preceding seasons. Unlike the ridiculously wet 2011 spring and summer seasons, and the equally parched months of 2012, fall banding was preceded by a spring and summer of relatively normal temperatures and precipitation. April was cool and wet, while May was overall quite warm except for a late frost in mid-month. Average monthly temperatures for June-October were close to the recorded averages for the period 1981-2010. Precipitation for June-October was also close to average, except for August. That month, the rainfall total was nearly three inches above average, but nearly 2.5 inches of that fell on one day, August 12.

Last year's drought caused a serious lack of fruit on shrubs and trees during fall 2012. Nature often makes up for lost productivity, and did so this year. The fruit crop on most plants was abundant if not phenomenal. As noted in my last blog post, the wild grape crop was the heaviest I have seen in over 25 years. Anybody who has an apple tree in their yard can attest that after last year's near complete crop failure, apples were so plentiful that trees broke under their weight. The same was true for their very close relatives crabapples and hawthorns.

The primary non-native fruiting species here are buckthorns and bush honeysuckles. They all seemed to flower and bloom a little later than usual this year, perhaps impacted by the May frost. However, they had large crops.

I noted only two types of fruiting plants that seemed to have below-normal crops. Black cherries, which were one of the few trees that fruited well last year, took a break this year with virtually no crop. Eastern redcedars also seemed to set less fruit than usual.

As might be expected with a modified banding season, we ended up banding a modest 550 new birds and handling 87 recaptures of 58 species. This includes two species released unbanded, House Sparrow and Ruby-throated Hummingbird. A total of 741 birds were netted (which includes birds released unbanded). Our capture rate was 39.4 birds per 100 net-hours. Here is how this fall compared with the 21 previous autumn seasons:

Fall 2013 Previous
fall mean
Days open 28 50
New birds 550 1177
Total birds 741 1502
Capture rate 39.4 48.0
Species 58 69

The top ten bird species banded this fall (new captures only) were:
  1. American Robin -- 118 (low; previous mean 189.7)
  2. White-throated Sparrow --49
  3. Common Grackle -- 35 (new high; previous mean 8.8)
  4. Song Sparrow -- 33 (new record low; previous mean 55.3)
  5. Gray Catbird -- 32 (same as last year, which was record low)
  6. Yellow-rumped Warbler -- 28
  7. Hermit Thrush -- 21
  8. Cedar Waxwing --19
  9. Nashville Warbler -- 16
  10. Ruby-crowned Kinglet -- 15
Numbers and Trends
The high number of grackles is just a hit or miss event. We get very large flocks near our banding site; flocks of over 500 blackbirds, of which most are grackles, is not uncommon in October. They occasionally get flushed into the banding area, but often do not "stick" in the nets.

Banding hummingbirds requires special equipment and a permit amendment, so we release them unbanded. If we didn't, they would have come in at #2 on the list with 40 captured. Some may be repeats of the same bird, but there are often 3 or 4 in the nets at the same time throughout the season, so this is close to an accurate number. They are most often caught in nets adjacent to two plant species at which they nectar: Spotted Jewelweed, a native wildflower; and Glossy Buckthorn, a non-native shrub. The latter has small blooms from early spring through fall and I frequently see hummingbirds using these flowers.

This is the first year we have missed banding any Gray-cheeked Thrushes or Philadelphia Vireos. This may be due to the timing of our gap in banding. This is the third year in a row we did not band any Wood Thrushes. Some years ago, Wood Thrushes were common nesting species here. This is a species that is declining over much of its range, and their absence here may reflect those diminishing numbers.

Both Swainson's Thrushes and Gray Catbirds continued a long-term decline in our nets that I have written about previously. Scrolling down on this page will present graphs on these two species, plus Hermit Thrush; the trend remains the same.

Last year I noted declines in our capture rate* over the last decade. For the first 13-15 years of banding, things moved up and down, but usually remained over 40 birds per 100 net-hours. The average for the years 1992-2004 was 51.6. Since 2005, there has been a pronounced drop. In fact, the drop was quite steep from 2005 to 2008, and since then it has more or less fluctuated in the 30-40 range.

Click to enlarge.

Two important things happened around 2005 that may help explain this: first, the bike path that runs through campus -- wrapping around 3 sides of the banding area -- opened. It gets a great deal of traffic. Second, we began experiencing canopy loss due to falling ash trees killed by the Emerald Ash Borer. This dramatically changed the character of the forested area at UM-Dearborn. Not only did it result in a different mix of trees and shrubs, but probably created a more open and inviting habitat for our increasing deer herd, which alter ecosystems themselves.

So many changes have taken place around our banding site over the years, including the construction of several nearby buildings, and a large, busy parking lot adjacent to the net lanes. Increased development, habitat changes at the site and landscape level, higher numbers of mammalian predators, weather events... it's not possible to tell what may be responsible for our declining capture rate. No doubt it is a combination of things, and we will be pondering the future direction of the banding program in the months to come.

We have only banded 6 Golden-winged Warblers in the past 21 fall seasons, so this bird on September 10 was a treat, and our first since 2005.

The past ten years of so, Northern Waterthrushes seem to be a little scarce, and some years we do not band any. Even just the four we banded this fall was better than we've done since 2006.

An interesting Orange-crowned Warbler was banded on October 14. It had large, distinct dusky centers to its undertail coverts. This is a feature more characteristic of the subspecies that is resident in California, and I've never seen it on any of the birds I've banded here in migration. Bill measurement can be helpful in distinguishing subspecies, and while this one was a little large, it was within the high end of the range of the subspecies expected to pass through Michigan.

A Sharp-shinned Hawk banded in mid-September.

Twenty-three individuals of 9 species of passage migrants (those which do not normally nest or winter in this area) were recaptured. Sixty-five percent of them maintained or gained mass. Half of the birds that lost mass were sparrows. This is fairly typical of this site; insectivores and frugivores tend to gain weight, while seed-eaters tend to lose weight, or gain just small amounts.

We also recaptured 13 birds banded in previous years. The oldest was a female Northern Cardinal first captured in October 2001, making it over 12 years old. Another old bird was a female American Robin first banded as an adult in 2008. She is at least 6 years old. You can view more longevity records here.

We obtained another 318 seed samples from 11 species of birds. This included two new "contributors": a Brown Thrasher (which had eaten pokeweed and grape) and a Willow/Alder Flycatcher (which ate honeysuckle). This brings our total sample size to more than 1,500. Over half are from American Robins, and other large percentages from Gray Catbird, Cedar Waxwing, and Hermit and Swainson's Thrushes.

Credits, kudos
Finally, I’d like to thank Dana Wloch, this year's assistant, and her sponsor, the Michigan Audubon Society. This is the second year in a row MAS has supported Dana's work helping with banding, completing many more species accounts on our seed identification website, and her continued work with our fall dietary study cleaning, sorting, identifying, measuring, and cataloging fruits and seeds. This banding season would not have happened without MAS and Dana, and the on-going work of RRBO could not continue without the support of many donors.


*In order to compare different locations or years that may operate the same number of hours but with more or fewer nets, capture rate is calculated by "net-hours." One net hour is one 12-meter net open one hour, or two 6-meter nets open one hour, etc. This rate is often expressed per 100 net-hours for more manageable numbers.

Weather statistics from the National Weather Service.