Friday, September 17, 2010

Neotropical migrants

Red-eyed Vireo - Vireo olivaceus

It's September, and migration is in full swing, not only in North America but also down here in Central America. In this blog entry, I want to highlight some neotropical migrants, i.e. birds that breed in North America but winter in Central or South America. Some of those birds have already arrived on their wintering grounds, while others are still passing through.

SalvaNATURA's bird monitoring program operates five bird banding sites in El Salvador, and - since January 2010 - one in Honduras. These sites are part of a network of more than 140 bird banding stations that collectively pool data in an initiative called MoSI, or Monitoreo de Sobrevivencia Invernal (Monitoring Avian Winter Survival). MoSI sites are operated in 14 countries in the northern neotropics, from Mexico down to Colombia, and together provide important data on many neotropical migrants. The MoSI initiative is coordinated by the Institute for Bird Populations.

This past week, SalvaNATURA operated the Honduran MoSI site in Monte Uyuca, near the capital Tegucigalpa. Following standard MoSI protocol, we operated 16 mist nets for a total of 25 hours, resulting in 400 net hours. In this pulse, we caught, banded and released 82 birds of 22 species - including several neotropical migrants. All photos shown here are of birds banded during that pulse.

The bird at the top, an adult Red-eyed Vireo of course, winters in South America. We banded two individuals this week, this adult and a hatch-year bird. Other transients we saw but didn't encounter in our nets include two Blackburnian Warblers, a Canada Warbler, and several Wood-pewees. Combining resident and migrant warblers, we got to 15 species observed - not bad for a place that's not a 'migrant trap', just a small part of a pine-oak/cloud forest site called Reserva Biológica Monte Uyuca! The warbler list this week included Golden-cheeked Warbler, an endangered species that reaches relatively high densities here in the core of its wintering grounds, and one we hope to encounter in our mist nets one day. We also saw all three Wilsonia warblers; of these, Canada Warbler is a transient, Hooded Warbler is more common on the Atlantic Slope, and only Wilson's Warbler is the common winter visitor here.

Worm-eating Warbler - Helmitheros vermivora

The Worm-eating Warbler breeds on steep slopes of deciduous or mixed forests in the eastern United States, and winters in Mexico and Central America and the Caribbean. This species appears to be increasing in its large range and is currently considered of Least Concern by the IUCN Red List of Threatened Species.

Tennessee Warbler - Oreothlypis peregrina

Tennessee Warbler, here in first-winter plumage, is another species considered of Least Concern by IUCN, for it too has a large range, and populations appear to be stable.

Black-and-white Warbler - Mniotilta varia

 The Black-and-white Warbler breeds in the eastern United States and in many of the lower Canadian provinces. Its winter range includes Florida, coastal Texas, Mexico, Central America, the Caribbean and northern South America. Still an abundant species, its population trend, however, appears to be slowly declining (IUCN).

Swainson's Thrush - Catharus ustulatus

Another neotropical migrant, and an abundant winter visitor in Central America, is Swainson's Thrush.

Yellow-bellied Flycatcher - Empidonax flaviventris

Yellow-bellied Flycatcher is one of the most common breeding birds of the Canadian boreal forest, yet remarkably little is known about many aspects of its life history, including its winter ecology.

Least Flycatcher - Empidonax minimus

Another empid we caught this week was Least Flycatcher. Note the proportionally large head, and, in comparison with its yellow-bellied congener, a darker head contrasting more with its whiter throat. This species has been better studied than Yellow-bellied Fly, although its winter ecology remains largely unstudied...

If you're a North American birder, then all these species are very likely most familiar to you. You welcome them back each spring as they pass through your area heading north, or arrive in your area to raise their young.

SalvaNATURA's bird monitoring program collects valuable data on these neotropical migrants, and contributes to our knowledge of their population trends and winter habitat preferences. If you believe in the value of this work, then please consider sponsoring our birdathon. All funds raised are used for SalvaNATURA's bird monitoring program.

How can I contribute
Sponsoring the birdathon is easy:
1) go to The Resource Foundation;
2) click on "Donate" on the right part of your screen, which opens a secure (https) connection;
3) select the amount you want to donate;
4) select whether you want to make a one-time donation or a recurring donation;
5) select "El Salvador - SalvaNATURA" in the pull-down menu called "Program Designation";
6) indicate in the "Dedication" that your donation benefits the "SalvaNATURA 2010 Birdathon";
7) send an email to the birdathon coordinator (john.vandort AT confirming your donation.

The Resource Foundation is a U.S. nonprofit organization that helps donors support effective, locally-driven development programs in Latin America and the Caribbean. Your donation through them is of course tax-deductible.

Thank you for your generosity!

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