Silent Spring after 50 years

Have we learned our lesson?

Fifty years ago this month the important book Silent Spring by Rachel Carson was published. This book warned about the lethal and persistent effects of the pesticide DDT. This book, while in some ways outdated, remains a classic not only for its role in inspiring environmental stewardship, but also because although DDT has been banned in the United States, as a society we still enthusiastically embrace a whole suite of chemicals that end up in our air, water, and soil (and ultimately in animals and ourselves). And we still tend to trust that they are perfectly safe.

In fact, testing of pesticides and other chemicals is focused specifically on active ingredients used in certain amounts and circumstances. Many people use chemicals in ways not intended by the manufacturers, in amounts beyond recommended volumes, in combination with other chemicals, and when none are really needed in the first place. Aside from the risks of these types of applications, we further know very little about the components of this toxic soup interact with each other and the environment.

An excellent example is the American obsession with cosmetic lawn and garden chemicals. I don't want to get too soap-boxy here, but I can tell you two things. First, you can have a nice lawn (if you must) and garden without the use of any chemicals. I've done this my whole life. Second, one of the best things you can do for birds (your pets, the ecosystem, and yourself) in your area is to quit using all chemicals in your yard, because they do harm birds.

I see the effects of "safe" lawn chemicals every year on common birds. I have held emaciated robins in my hands as they had seizures and died, and looked up from their lifeless bodies to rest my gaze upon those little signs indicating an expanse of grass was sprayed with some concoction. Without direct toxicology tests, I can't honestly say lawn chemical exposure was the direct cause of these deaths. I do know that robins can't read to keep off the grass, that their symptoms are typical of exposure, and it is far too common an occurrence to not at least suspect that some combination of chemical exposure is to blame.

On this anniversary of the publication of Silent Spring, I encourage you to read or re-read this book and related material. We are in an age where enough data is available for us to be truly informed and where our actions can make a real difference. Unfortunately, we are also at a point where we are distrustful of science, and often bombarded with conflicting messages from special interest groups. I don't have a horse in this race, except my love for the natural world. Here are my recommendations:

An excellent overview of the context and impact of Silent Spring can be found at the Pop History Dig website: Power in the Pen: Silent Spring 1962. The New York Times Magazine also recently published How Silent Spring ignited the environmental movement.

The book itself, Silent Spring (Kindle edition here), as well as a new biography of Rachel Carson, On a Farther Shore: The Life and Legacy of Rachel Carson (Kindle here).

I also strongly recommend Our Stolen Future, which further explores synthetic chemicals in the environment.

There are many excellent sites on thee continued risk of chemicals many of us continue to use regularly. The non-profit Environmental and Human Health published a report very worth reading: Risks from Lawn Care Pesticides. The organization Beyond Pesticides has extensive information about pesticide issues, risks, and alternatives.

MIA: young birds

In our last update, I mentioned that I thought the hot, dry summer might have resulted in low productivity -- fewer young birds fledged. Fall banding is an excellent way to assess productivity, as the ratio of young to adult birds is easy to tally. Here at RRBO, about 81% of the birds we band in fall are young-of-the-year, known to banders as "hatch-year" birds. This is fairly typical, although coastal banding stations may see 90% or higher, since young songbirds often follow slightly different migration routes than adults, and seem to favor coastal routes.

So far this fall, the number of adult birds we are banding has been unusually high. Sometimes we see this in individual species, but it seems like it is across the board so far. I took a look at the first month of fall banding for all years prior to this year combined, and noted that 86% of the birds banded were hatch-year birds. Since we begin banding in August, we usually start out banding a lot of the recently-fledged resident birds, especially catbirds, so the slightly higher percentage compared to the overall fall average is expected. This year so far, only 68% of the birds have been hatch-year.

We will have to see how this plays out over the season. I am especially concerned at the overall low numbers of American Robins and Gray Catbirds, especially young birds. I will address these in a future post.

Let's look at a more cheerful graph -- the composition of warbler species banded so far this fall.

The "other" category are three species for which only single birds have been banded: Black-and-White, Cape May, and Palm Warbler.

Since it's so early in the season, it's hard to say whether or not some of these species will be banded in larger numbers than usual. Nashville Warblers are one our most frequently-banded species; they have a long migration period so this graph is not very revealing. My gut based on the last 20 years is that redstarts may end up being more numerous this year than usual. Right now they comprise 24% of the warbler species banded. The overall fall average is 12%.

It looks like the summer-like weather is gone for the next week, and a dramatic shift in the jet stream over the coming days is likely to bring in lots of birds. Stay tuned.

August banding

Fall banding 2012 started on August 17. As I suspected, things have been slow. The very hot, dry summer seems to have resulted in low reproductive productivity for our most common local breeding bird species, such as American Robins. It's just difficult for them to find ground-dwelling invertebrates to feed their young when it is so dry.

Rather than just summarize numbers this fall banding season, I'd like to focus more on one of our current research projects: the fall diet of birds. As regular followers know, RRBO's research focus is on the fall stopover ecology of migrant birds, in particular what kinds of fruit birds are eating in this urban forest patch. We do this by collecting seeds passed by the birds that we band when they poop in the bags we transport them in. This is the 6th year we have collected samples from Catharus thrushes (Swainson's, Gray-cheeked, and Hermit), and the 4th year we have done expanded sampling on all bird species.

Through 2011, we have collected samples from over 1,000 birds of 17 species. Of the nearly 6,400 individual seeds in these samples, only nine have gone unidentified (I'll describe in detail in a future post how we identify all the seeds). Twenty plant taxa are represented in the samples, and most seeds have been identified to species. Thus, we have a great picture of which species of fruit are being eaten by birds.

Pokeweed fruit.

In August, we collected samples from 18 birds. Pokeweed was the most common seed, showing up in 11 samples. We had our first ever sample of poison ivy from a catbird. Usually, this is consumed by woodpeckers or Yellow-rumped Warblers, and nearly always in October. Like quite a few plant species, poison ivy seems to have flowered (and thus set fruit) earlier this season. Other plants may have budded or flowered early (given the long stretch of hot weather in March), then failed to fruit either due to frost in April, or because of the long dry period in summer. We have virtually no crop of wild grapes or relatives such as woodbine/Virginia Creeper. A number of other shrubs that are staples in the diets of fall birds here are ripening late; some portion of shrubs did not set fruit at all.

Poison ivy flowers

Our data for this hot, dry growing season should be an interesting contrast to last year's exceptionally wet summer and add substantially to our picture of what birds eat during fall in an urban natural area.

Dearborn Passenger Pigeons: Then and Now

I recently became aware of an interesting website: Project Passenger Pigeon.  Since 2014 marks the 100-year anniversary of the extinction of Passenger Pigeons, a group based out of the Chicago Academy of Science is using its story as an opportunity to educate people about extinction, habitat preservation, and species conservation.

The web site is very extensive. Among many other topics, it provides a great deal of information on Passenger Pigeons in various states, including a good account of the bird's history in Michigan. I'd like to add to this historical account because Dearborn figures in Michigan's Passenger Pigeon history, as I found out when I was researching my book, "The Birds of Dearborn: An Annotated Checklist."

On September 14, 1898, a Passenger Pigeon, one of three birds observed, was collected by Frank Clements. The first authoritative book on Michigan ornithology was Michigan Bird Life by W. B. Barrows, published in 1912. That book reports the location of these pigeons as "Delray" which is an area in southwest Detroit. Further digging has revealed that this location is not correct.

In a note published in the short-lived Bulletin of the Michigan Ornithological Club, Philip Moody -- who was with Clements at the time of collection -- identified the location as "Chestnut Ridge." My previous research indicated that this was a large woodlot owned by the Chestnut Ridge Land Co., also marked on some maps as Private Claim 31, on the southwest side of the Rouge River near what is now Rotunda Drive. Several years later, J. C. Wood, another prolific collector of birds in Wayne County, clarified with Moody the precise location: Private Claim 660, Dearborn Township.

Thanks to modern technology, we can look at the 1876 historic map of Dearborn Township overlaid with today's Google Maps (you can zoom and adjust transparency) and see that PC660 stretched from the Rouge River southwest to just past the intersection of Rotunda and Pelham; most of the area is now Greenfield Village. At the time of Wood's 1910 note, the specimen was in Toronto in the collection of James Fleming, a well-known Canadian ornithologist. This specimen is currently at the Royal Ontario Museum in Toronto, and the locality is listed (incorrectly) as "Delray, Detroit."

The Dearborn/Delray bird is often cited as being the last collected in the state, although a search of the ORNIS database reveals a specimen housed in the Yale University Peabody Museum from Bay County in January 1906. Fleming's careful research as well as many other references fail to mention this bird or other wild birds in our region past 1900 or so; perhaps this one was a captive bird. Thus, the Dearborn bird is generally considered the last wild Passenger Pigeon collected in Michigan, and one of the last in the region.

The Project Passenger Pigeon web site also lists all the known specimens of this species, and includes 11 locations in Michigan. I will add one more: right here in the University of Michigan-Dearborn's Environmental Interpretive Center.

The pigeon is in a large vintage Edwardian-type glass case, with an unlikely assortment of stuffed specimens of many other birds.

The case was given to the former director of the EIC, Orin Gelderloos, well over 20 years ago. It is not on public display, but is still housed here in the EIC.

The Passenger Pigeon is on the bottom of the case. A Blue Jay perched above it gives some idea of the size of this large bird.

Details on the age of the case -- which if not Victorian-era is certainly of that style -- or the origin of the birds in the case are not indicated on the case and remain a bit of a mystery. The bird species in the case are all native to Michigan with the exception of the European Goldfinch in the upper center (although this species was released in the Dearborn area by Henry Ford a hundred years ago, that flock did not persist).

Whatever its provenance, the Passenger Pigeon in the case reminds us of Dearborn's place in the sad history of this species.

References:

Barrows, W.B. 1912. Michigan Bird Life. Michigan Agricultural College, Lansing.

Fleming, J. H. 1907. On the disappearance of the Passenger Pigeon. Ottawa Naturalist 20: 236-237.

Moody, P. E. 1903. A recent record of the wild pigeon. Bulletin of the Michigan Ornithological Club 4:81.

Wood, J. C. 1910. The last passenger pigeons in Wayne County, Michigan. Auk 27:208. (PDF here)

Spring 2012 survey results

The spring 2012 survey season took place 3 April through 4 June. On campus, regular surveys were conducted on 58 of the 65 days; some coverage late in the season was truncated due to field work related to our catbird study. Because of the unusual weather (discussed below), surveys were also conducted on 21 days in March.

Excluding March, the campus surveys recorded 124 species (another 19 were recorded in Dearborn off-campus). This is lower than the previous ten-year average of 130 species. The peak day was 3 May with 79 species. This is a similar to our usual peak day total of 80 species, but usually the peak occurs much later in the month (around May 16-20). Both the low species totals and early peak are at least in part attributable to the extremely early leaf-out, which made visual detection of mid- and late-season migrants much more difficult.

Weather
This leaf-out -- in which leaf and flower phenology was some five weeks ahead of schedule by April -- was due to the unprecedented hot weather in March. The National Weather Service characterized March 2012 as the warmest on record and the most unusual month in Detroit's history. The average temperature for March was 50.7 F, an incredible 15.6 degrees above the 1874-2011 mean average of 35.1F! Fortunately, the weather did cool down, with April temps right at normal, but May was the 3rd warmest on record. Thus, spring 2012 finished the warmest in southeast Michigan history.

Generally, warm periods in spring that accelerate plant growth also prompt early emergence of insects. This can result in a mis-match between insect resources and the timing of bird migration, especially for birds that are coming from wintering grounds in the tropics. These birds are prompted to migrate by changes in day length, and do not "know" that spring is advanced in the north. The same weather systems that bring warmth to the north may push migrants which have already arrived in the United States northward a little faster. This year, long-distance migrants that had yet to arrive during the early part of the season arrived right about their usual time (see Arrival dates, below).

There were some real concerns that had the hot weather continued, things would have gotten seriously out-of-whack -- you can read my blog post What does summer in winter mean for birds? for a discussion of potential ramifications. Fortunately, cooler weather in April slowed phenology down a bit. While we did have freezing overnight temperatures after the March hot spell, they did not last for many hours in the Detroit area, so insect life was not seriously diminished and it appears that migrants were able to find adequate food resources.

Spring 2012 was also quite dry...especially when compared to last year! In 2011, the precipitation total for Detroit from March through May was over 14 inches. This spring, it was less than half of that, with both April and May having below-average moisture.

While migrants dodged a resource bullet, it seems this combination of advanced plant and insect phenology and dry conditions is likely to have had some impact on breeding birds. This probably depends on how reliant various birds are on particular stages or species of insects as well as the impact weather may have had on a very small landscape scale at locations where birds nested. Perhaps we will detect some changes in the ratio of young to adult birds during fall banding that may shed some light on this. Finally, because they flowered early and pollinators were out and about, many fruiting plants also set fruit early. Fruit is a critical part of the diet of many fall migrants; we'll see if there are any changes in what birds are eating this fall.

Highlights
Many of the less-common migrants we have come to expect on a nearly annual basis were not recorded this year. This includes Golden-winged Warbler, Prothonotary Warbler, Kentucky Warbler, and Summer Tanager. Acadian and Olive-sided Flycatchers and Philadelphia Vireo were also missed. The most interesting highlight was the number of White-eyed Vireo sightings: five from mid-April to mid-May. Leaf-out was so advanced by mid-May, that many birds, especially non-singing females, may have gone undetected.

I'll add a lowlight on a species I follow and mention frequently: American Crow. Of the 61 days in April and May, crows were recorded in the entire city of Dearborn on only 15 days. Reports were always of one or two birds. Crows were seen more often in March, as observations include migrating birds. In March, crows were reported on 14 days, mostly in ones or twos, with a high number of 11 birds in a flock on 13 March.

Arrival dates
The March hot spell created a flood of reports of early migrants. Many of these are probably best viewed with caution (see my post Early Neotropical migrants for more discussion). Of the 43 migrant species for which we have adequate reliable arrival data, 31 did arrive earlier than the average date calculated through 2011. Both the median and the mode for the number of days early for these species was 2 days. Thirteen species arrived four or more days earlier than average. A few short-distance migrants had record-early dates for Dearborn:

• Tree Swallow on 18 March, previous early date 22 March
• Field Sparrow on 18 March, previous early 24 March
• Chipping Sparrow on 26 March, previous early 30 March

Of the long-distance migrants, new records were:

• Nashville Warbler on 16 April, previous early 20 April
• Canada Warbler on 4 May, previous early 5 May

So, nothing particularly outstanding. Many thanks to Darrin O'Brien who assisted with surveys this spring.