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.

Wednesday, February 17, 2010

Winter Bird Population Survey, Year 18

Last year I introduced readers to our annual Winter Bird Population Survey. I've just completed the 18th year of this survey, recording two new species.

The two new species were: Mute Swan (two birds flying over on 4 February), and a Long-eared Owl on 21 January. This brings the total cumulative species list to 69. The number of species that have been recorded in only one year is now 15, and the number of species that have been recorded every year is 21.

Every year since 2002, the year West Nile Virus was first detected in Michigan, I have lamented the loss and subsequent lack of recovery of American Crows. This winter, only a single crow was counted during the survey period. This is the seventh year in a row with fewer than 10 total counted on the survey. The average number of crows found over the survey period prior to WNV was 139; the mean since (2003-2010) is 7. I know of only two pairs of crows nesting in Dearborn. I don't know if these four birds have some sort of immunity to the virus, but I find them in the same place every year, and they don't seem to produce any surviving young.

Tufted Titmouse is another species that suffers high mortality from West Nile virus. They seem to have made a come-back in recent years, and this year the survey recorded the highest number since 2002.

Sparrows in general were seen in lower numbers this winter, but this could be due to the fact that the many of the Ford properties, which typically attract thousands of birds and which we tend to see a little overflow, were harvested bare this year.

American Robins were plentiful, as they have been most recent years. This is the eighth year in a row where they have been recorded on 75% or more of the survey dates (the survey period runs from 20 December to 20 February). The average number of robins seen on each visit has also been increasing, as the graph below indicates.

So long as robins are able to access some water (although they will eat snow) and have a supply of food (mostly fruit, but also invertebrates in leaf litter, so snow cover is a handicap), they'll stick around.

Other than those "highlights," it was a rather below average winter. I tallied 37 species, just one species below the average. Other parameters, such as individuals counted per hour or per visit, were also slightly below average, although not dramatically. However dull, long-term data like this is very important for detecting population trends and responses to climate change, habitat alteration, or pathogen introductions, as the robin and crow examples illustrate. And since this survey uses multiple visits over the winter season, it is more robust than one-day counts such as the Christmas Bird Count. In fact, it is probably the unsung hero among the many datasets RRBO has put together over the years.

You can view an introduction to how the Winter Bird Population Survey works, as well as all the results, on the RRBO web site.

Saturday, February 6, 2010

How to detect ruffled feathers

One of my favorite non-bird books is The Songs of Insects, a fabulous guide to dozens of species of crickets, cicadas, and katydids. Photographer Wil Hershberger's web site has a page where he notes the presence of two small filoplumes on the napes of songbirds he'd photographed. Filoplumes are specialized feathers, long and hairlike, that are most numerous at the base of wing feathers. Special sensory cells at the base of filoplumes transmit information on the position and movement of wing feathers during flight. According to the Manual of Ornithology: Avian Structure and Function, many passerines also have filoplumes sticking out of their crown and nape, "perhaps warning the bird when wind disrupts the smooth outer surface of the plumage."

I found this incredibly intriguing, and when I had the time, I looked for these plumes on the birds I banded. Sure enough, there they were! I was able to find them on a variety of species, both male and female, and could even see them on some older head shots I had taken during previous fall banding seasons. Although not particularly easy to photograph (especially with one hand!), here is a little slide show of some of my shots. Look at the back of the neck -- you might have to slow the speed down a bit or pause on some photos. (Note: apparently some Firefox users cannot see the Flickr slide show, a known bug with Flickr. If you have a Flickr account, it might help to log in.)

Species in order: Yellow Warbler (male then female), Orchard Oriole, Black-and-white Warbler, Brown Thrasher, White-throated Sparrow, Tennessee Warbler, Magnolia Warbler, Rose-breasted Grosbeak (male then female), Black-thr Green Warbler, Connecticut Warbler, Golden-winged Warbler, Nashville Warbler, Purple Finch, Wilson's Warbler, Baltimore Oriole, Common Yellowthroat. Created with Paul's flickrSLiDR.

A 1989 paper (pdf) in the Condor, the journal of the Cooper Ornithological Society, described the presence of these protruding filoplumes on the napes of many passerine species. The authors noted that species which lacked these plumes had dense, stiff feathering on their napes, while species that displayed the filoplumes had softer and more flexible feathering in this area. They also concluded that these plumes served to detect disturbances in the feathers in an area that birds could neither see nor reach. The looser plumage might have less insulative properties to begin with, and unnoticed disheveled plumage might make a bird even more vulnerable to heat loss. A quick shake or perhaps scratch of the head, or facing into the wind can smooth the feathers once again, correcting the situation.

It's hard to believe I handled tens of thousands of birds -- with part of the routine being close scrutiny of plumage -- without making particular note of this interesting characteristic!

Monday, February 1, 2010

Banding recovery: Michigan robin in Louisiana

We received a report of a young American Robin banded here on campus 28 October 2005 being found dead in Georgetown, Louisiana. There was no specific information on the date the bird was found, only "2009." Georgetown is in Grant Parish in north-central Louisiana, near the eastern border of the Kisatchie National Forest.

This is the 8th robin (out of nearly 3500) we have had recovered from out of state, and the third from Louisiana. Four more were also from the deep south, and one was from Ohio.

You can view a table and an interactive map of all of the birds banded at RRBO that have been recovered outside of Michigan on the RRBO web site.