Thursday, June 10, 2010

Spring 2010 migration in review

The spring 2010 survey season took place on 47 days between 1 April through 4 June. There were surveys on most mornings in April and nearly every day in May except during heavy rain. As in past years, each survey always included a 1.5-mile standard route in the natural area on campus. Many days, additional area was covered; distance, time, and birds counted on these legs were recorded separately but are discussed below in aggregate. On campus, 129 species were recorded (another 9 were recorded in Dearborn off-campus). This equals the previous 12-year mean. The peak calendar week was 16 through 22 May with 92 species. This is the same peak week as 2009, but last year 95 species were recorded that week. The peak day was 16 May (18 May last year) with 76 species (ten fewer than 2009). Weather The National Weather Service reported that 2010 had the warmest spring on record for Detroit, and the warmest spring since 1991 across most of the southern Michigan region. This was largely due to warm temperatures in March and April (both months in the top 20 warmest lists for southeast Michigan). The first week in April was particularly hot -- the warmest first week in April in climate history at Detroit, Flint, and Saginaw. However, there were below-average temperatures the second week in May. At Detroit much of the spring was dry, with precipitation well below average through the end of April. Rain in May helped boost precip levels up and much of the region was near-normal by the end of May. These weather patterns were guided by a jet stream that was generally south of our region up until May. General trends One inevitable result of warm weather early in the spring is that trees leaf out earlier, making detecting birds more difficult. While most spring birds are recorded by hearing them sing, this obviously doesn't work with silent birds, especially females. The understory here on campus is now dominated in most areas by non-native shrub genera that also tend to leaf out early: Lonicera (honeysuckles) and Rhamnus/Frangula (buckthorns). These hindrances to detectability may have played a role in overall low numbers of many species of migrants, and late season migrants in particular. Species that make up the caboose of spring migration here, such as both cuckoos and Blackpoll, Canada, and Mourning Warblers, were found only in very modest numbers over a period of just a few days. I hope that detectability, favorable weather promoting migration past our site, or some other benign factor was responsible for the lack of late-season migrants. We will probably never know if the burning of oil from the Deepwater Horizon catastrophe in the Gulf disoriented, sickened, or killed migrant songbirds. Whether it did or not, we can only wait and see how it effects southbound migrants, directly or indirectly. As of this writing, unknown thousands of barrels of oil are still belching from the sea floor. Right now, our minds are with the waterbirds, sea creatures, and humans that are being immediately and urgently impacted by these malignant plumes of oil. I'm sure we have yet to imagine the profound and far-reaching impacts this disaster will have on wildlife -- maybe even migrant songbirds -- in the years to come. Already troubling to me is the apparent decline in the number of individuals of some common species. Black-throated Blue Warbler, Black-and-white Warbler, American Redstart, and Ovenbird are good examples. The number of individuals of each of these species posted a greater than 30% decline over the average number counted the previous three years. This ranged from 33% fewer redstarts to 57% fewer Black-throated Blue Warblers. These numbers have not been adjusted for effort, but effort has been similar the past four years, hence the short time frame given. In a few more months, 17 years of daily spring surveys with effort data will be digitized and available for analysis, providing a much clearer picture. But even this back-of-the envelope calculation may be cause for alarm, as this suite of species has something in common: they all winter primarily in the West Indies. John Faaborg's excellent long-term winter banding project in Puerto Rico has noted very alarming declines in some of the most common wintering North American migrants on his study plot -- and both Black-and-white Warbler and Ovenbird have declined to less than 20% of their original abundances since 1973. Migrant birds have complex life histories, so it is hard to draw conclusions from one year and one place. If you are interested in the struggle to understand how to monitor and evaluate migratory songbirds, I recommend this excellent overview (PDF): Conserving migratory land birds in the New World: Do we know enough? Ecological Applications 20:398-418. You don't need a lot of technical chops in bird ecology to get the gist of what we are up against when you read this paper. You can help! There is power in large amounts of data. For this reason, I encourage all readers to consider contributing their past and future bird data to eBird. I believe this is our best hope for strong evidence to shape conservation of birds for decades to come. Back to spring 2010... Arrival dates Only a few species posted record early spring arrival dates this year. Blue-gray Gnatcatchers arrived on 8 April, four days earlier than the previous early date. On 15 April, a Blue-headed Vireo showed up, four days early. When they were recorded on 16 April, Chimney Swifts were two days early. I keep track of the arrival dates of over 40 species of conspicuous (easily detectable) migrant species. About half of these species arrived earlier this year than the previous 16-year mean (an average of 4 days earlier), while about half arrived later (average 3 days later). More interesting, perhaps, is comparing the 2010 arrival date with the mean for the first 7 years (for most species, 1993-1999). In 2010, 62% of species arrived earlier than they did during the early 1990s, an average of 5 days earlier. The 31% that arrived later did so on average of 3 days later. If we look at this group of species and compare the early period (for most species, 1993-1996) with the current period (2003-2010), the trend toward earlier arrivals is even more pronounced. Nearly 79% of species are arriving earlier (by an average of 4 days), while less than 17% are arriving later (3 days). This method uses arithmetic means, and more rigorous statistical testing over longer time periods will be done once digitization of all years of spring survey data is complete. Highlights Notable birds were rather few and far between this year. No outstanding rarities were recorded. A number of less common species were found on campus: Common Loon (flyover, 15 Apr), American Coot (7 Apr), Sandhill Crane (flyover, 5 May), Red-headed Woodpecker (5 May), White-eyed Vireo (25 and 30 May, probably the same bird), Hooded Warbler (6 and 21 May), Summer Tanager (14 and 19 May), and Orchard Oriole (1 May, and another bird that arrived on 23 May and was present through the end of May). Perhaps more notable were the birds not recorded. For the first time in 18 years, we did not record any Blue-winged Warblers, normally a common species. Other species that are annual here but were missed this year -- Philadelphia Vireo, Orange-crowned Warbler, and Connecticut Warbler -- can be difficult to find and have often been picked up during banding operations versus surveys. Because we do not currently have a spring research project that can be addressed by the capture of birds, we did not band birds again this spring and so did not record these species. Many thanks to Darrin O'Brien and Jerry Sadowski, who assisted with surveys this spring.

Monday, May 31, 2010

How to help baby birds

The calls have already started. "I found a baby bird. What should I do?"

The answer is nearly always: leave it alone.

The vast majority of these birds are not orphans. Invariably, the ones that are "rescued" by well-meaning people end up dying because the folks that bring them home are like the proverbial dog that caught the bumper. Once they catch it, they have no idea what to do with it.

It is perfectly normal for a baby bird to leave the nest before it can fly. Baby birds grow rapidly, with many species leaving their crowded nests inside of two weeks. They are awkward, not fully feathered, and cannot fly.

American Robins, for example, can't fly when they leave the nest and are often found bumbling around, apparently alone and helpless. However, even if they are on the ground, their parents are most likely tending to them. The parents may be off finding food, or just in hiding because they are more wary of you than the young ones are.

If the baby is in immediate danger of being stepped on, run over, etc., you can move it a short distance. It isn't true that the parents will abandon it if it has been touched by a human. Do not chase the baby bird all around trying to catch it. The stress can kill it. If it can evade you, it can likely evade a predator.

Sometimes a nest gets blown down in a storm. You can reconstruct a nest in a container with drainage (like a berry basket) and securely fasten it near the original site. Do not try to raise the young yourself, it is not only difficult, in the U.S., it is illegal to possess a native bird.

If the bird you find is truly abandoned, it may be that by the time you find it, it is already too late, especially if it is a very young, naked baby bird. If you must take in a baby bird --

  1. Make sure it is a native species (see below). Many rehabbers will not take non-native species, and the release of non-native species is prohibited in some areas.
  2. Put the bird in a covered, ventilated box lined with a folded towel. Put it in a quiet, warm place, away from pets and children. In case you were wondering, yes, there are diseases you or your pets can contract from wild birds.
  3. Do NOT try to feed the bird or give it water. You can easily kill it.
  4. Contact a licensed wildlife rehabilitator immediately (Google "wildlife rehabilitators" and your locality). Raising healthy baby birds takes nearly 24-hour specialized care and knowledge of the nutritional needs of each species at different ages. Sick birds are even more complicated. Again, under the Migratory Bird Treaty Act, it is illegal to possess a native bird without special permits.

The species you are likely to encounter are common, prolific, adaptable, and will have more than one brood of youngsters a year. Loss of eggs, nestlings, or fledglings is normal for all bird species and built into "the system."

A huge percentage of the calls I receive are for House Sparrows, European Starlings, or Rock Pigeons -- none of these are native to North America. It does not make ecological sense to spend time and resources "saving" these species, which are already overabundant. They are not protected under law by the Migratory Bird Treaty Act, and it may be/become illegal for these species to be rehabilitated and released into the wild.

It is not easy for many people to "let nature take its course," but it is nearly always the right thing to do.

Download RRBO's brochure on what to do if you find a baby bird (PDF).


Thursday, March 18, 2010

RRBO on WDET

On March 15, I was on Detroit Public Radio, talking about bird population numbers on the Craig Fahle Show. I thought it went pretty well, considering I had no idea what he wanted to talk about besides "bird numbers"! You can listen to the show here (it's an MP3 link); I'm on about 2/3 of the way through the show.

Monday, March 15, 2010

Banding recovery: Michigan robin in Mississippi

Hot on the heels of a report of an RRBO-banded robin found in Louisiana last month, is another southern recovery. This robin, first banded here on campus as a hatching-year bird on 30 September 2007, and was found dead 5 miles north of McLain, Mississippi on 8 March 2010.

Interestingly, we recaptured this bird on 11 October 2008, when we determined it was a female. The bird was molting wing feathers when it was recaptured, which birds typically do on the breeding grounds rather than during migration. Recaptures of passage migrants are quite rare, as well, so this was likely a bird that nested somewhere on campus or nearby.

This is the 9th robin banded on campus recovered outside of Michigan. Most of them (6) were originally banded in fall (the others in spring and summer), and recovered en route to, on, or en route back from their wintering areas. This map shows all 9 areas where the robins were recovered. The Ohio bird was found just a month after it was banded in fall, so it was likely still southbound. You can click on the markers for details.



This is certainly demonstrating a pattern of Michigan robins -- breeding or migrant birds -- wintering in the southeastern U.S.

A similar map and chart of all of our out-of-state banding recoveries is on the RRBO web site.

Friday, March 5, 2010

Banding in Mexico

My husband Darrin and I have just returned from a trip to the western state of Jalisco, Mexico (highlighted above). You might recall that last year we went to Nicaragua where we conducted bird and insect surveys and did some bird banding on a shade coffee farm. This Mexican trip was sponsored by Rocky Mountain Bird Observatory in Colorado, which has done a great deal of work in this area. Our trip supported conservation work in Jalisco, an area where there are many endemic bird species found nowhere else in the world.

While our itinerary took us to several locations, I'll focus here on a visit to the Las Joyas research station in the Sierra de Manantlán Biosphere Reserve, where we, too briefly, learned about and lent a hand in one of the longest-running and most intensive bird banding projects in Mexico.

The Sierra de Manantl├ín Biosphere Reserve covers 1400 km² (roughly 350,000 acres). It was established in 1987, after being acquired by the government to preserve a large population of a rare species of wild maize, Zea diploperennis. The 345 km² of tropical dry forest in the reserve is the largest of its type protected in Mexico, and the 50 km² of cloud forest portion is the largest protected on Mexico's Pacific slope. Much of the land in Mexico is owned communally under the ejido system. Because there are so many landowners, biospheres in the country are structured so that there is a core area in which little or no human impact is allowed, and a buffer zone where managed activities such as sustainable agriculture can take place. A general map of the area is here.

The Las Joyas field station is operated by the University of Guadalajara in the core zone, and is not open to the public. If you put these coordinates <19.586010,-104.274028> into Google Maps or Earth and zoom in on the marker, you can see the buildings as well as the remoteness. The station is quite rustic, with solar power and outhouses with composting toilets. We slept in a dorm, 4 beds to a room, with thin walls that did not keep out the night-time chill at nearly 2000 meters! We were also warned to use a flashlight and beware of mountain lions and jaguars if we went to the outhouses at night. Four other wild cats are also common there: bobcats, ocelots, margays, and jaguarundis. Alas, we did not see any of them.

In the center is the dorm at Las Joyas; outhouses at left and kitchen at right.

The area around the dorms was full of bird life. The most common species were many usually-hard-to-see Crested Guans (Penelope purpurascens), roosting in the trees and flying back and forth; multiple sallying Tufted Flycatchers (Mitrephanes phaeocercus); several male Brown-backed Solitaires (Myadestes occidentalis) in constant song; and a pair of uncharacteristicly cooperative Blue Mockingbirds (Melanotis caerulescens). Singing Quail (Dactylortyx thoracicus) and Long-tailed Wood-Partridge (Dendrortyx macroura, a Mexican endemic) also lent their voices to the morning chorus; we got great looks at the wood-partridges at the compost pile.

The banding "station" is a table set up along a trail. Ten nets are run two days a week all year long, manned by station regulars and students working on various projects. I was very impressed by the speed and skill of the student banders, as well as the many scientific publications which have resulted from work here.

At left, University of Guadalajara's Sarahy Contreras explains some background of the banding project at Las Joyas, in which she has been involved for many years.

We just didn't take enough pictures. The pace of bird captures was steady in the morning. The students or Darrin and I were nearly always off checking nets, extracting birds, and bringing them back to the banding table. We were happy to help out even as most of our group went off for a walk.

The most common North American migratory species were Wilson's Warbler and Nashville Warbler. Most of the birds were residents, though, and a lot of them were hummingbirds.

They had a whole range of tiny hummingbird bands arranged in mint tins, and an array of special banding pliers to put the bands on. Some species we had that day were White-eared, Magnificent, Rufous, and Berylline Hummingbirds, and Green Violetear.

Here are a few of the highlights for me:

Cinnamon-bellied Flowerpiercers (Diglossa baritula) feed on nectar. The long hook at the tip of the bill is used to hold flowers firmly, while they stab the base of the flower corolla with their pointy lower bill and extract nectar by inserting their tongues through the slit. This is done incredibly fast! This is a small bird, perhaps the size of a Magnolia Warbler.

Golden-browed Warbler (Basileuterus belli).

Dwarf Vireo (Vireo nelsoni). I think this was the only bird we heard in the field but only saw in the hand. It is a very poorly known species endemic to Mexico. It's nearest relative is the endangered Texas-breeding Black-capped Vireo (Vireo atricapillus) -- one of which we also saw at a lower elevation! Black-caps have a very restricted wintering range in western Mexico, and the bird we saw was banded, most likely at the same wintering site by Sarahy two years before.

We had 8 species of vireo on the trip, including Golden Vireo (Vireo hypochryseus) and Chestnut-sided Shrike-Vireo (Vireolanius melitophrys).

Of course, as in Nicaragua, I was happy to get an opportunity to handle a couple of south-of-the-border Catharus thrushes, related to the birds I study here at RRBO.

Here is an Orange-billed Nightingale-thrush (Catharus aurantiirostris). They are smaller than a Hermit Thrush, generally the smallest Catharus thrush we get here in Michigan.

And here I am with a Russet Nightingale-thrush (Catharus occidentalis).

On the trip, we saw many other spectacular species. Among my favorites were:
Citreoline Trogon (Trogon citreolus) -- endemic to Mexico.
Pale-billed Woodpecker (Campephilus guatemalensis) -- a relative of the extinct Imperial and Ivory-billed Woodpeckers.
San Blas Jay (Cyanocorax sanblasianus) -- endemic to Mexico.
Red-breasted Chat (Granatellus venustus) -- endemic to the Pacific slope of Mexico.
Red-headed Tanager (Piranga erythrocephala) -- endemic to Mexico.
Rufous-capped and Green-striped Brush-Finches (Atlapetes pileatus and Arremon virenticeps) -- both endemic to Mexico.
Rusty-crowned Ground-sparrow (Melozone kieneri) -- endemic to west Mexico.
Orange-breasted Bunting (Passerina leclancherii) -- eye-popping Mexican endemic.

Our small group tallied around 250 species. Many thanks to Arvind Panjabi, Sarahy Contreras, Eduardo Santana, and Siux Diaz for hosting this great trip.