Navigation Links
Early environment may be key to determining bird migration location
Date:2/18/2008

How young migratory birds choose the nesting location of their first breeding season has been something of a mystery in the bird world. But a new University of Maryland/National Zoo study of the American redstart suggests that the environmental conditions the birds face in their first year may help determine where they breed for the rest of their lives, a factor that could significantly affect the population as climate change makes their winter habitats hotter and drier.

We found that where the birds go in their first winter, a process called natal dispersal, may determine the area, within several hundred miles, where they will breed over their lifetime, said Colin Studds, the University of Maryland PhD student who led [C1]the study. An important factor appears to be the availability of water in their winter habitat.

The study appears in the February 18 issue of the Proceedings of the National Academy of Sciences. Co-authors of the paper are Peter Marra, of the Smithsonian Migratory Bird Center, and Kurt Kyser, of Queens University, Ontario.

The Rich Get Richer

The American redstart is a warbler that migrates between breeding grounds in North America and winter spots in the Caribbean and South America. The team studied redstarts that winter over in Jamaica in two very different habitats that are right next to each other.

One is a very lush mangrove with water and lots of insects for the birds to eat, Studds said. Right beside it is a fairly harsh dry habitat, with very little water and not as good a food supply.

By studying the tail feathers of young redstarts between their first and subsequent summer nestings, the researchers found that the difference between wintering over in the lush mangrove or in the drier real estate next door may help set off a lifelong cycle of habitat location.

The mangrove birds leave earlier to breed, dont migrate as far north, and return to the water and food-rich mangrove. The birds from the lower rent district leave later for breeding grounds, must migrate farther north, and when they return to Jamaica, the mangrove is occupied and they are, once again, scrabbling in the scrub.

The Cycle

The cycle begins for the young redstart when it leaves its northern birthplace and migrates south for its first winter. Studds team measured a hydrogen isotope called deuterium, found in the fledglings tail feathers, an indicator of where the bird was hatched and, in subsequent summers, where it breeds. Once the isotope in the feathers, it doesnt change, Studds says.

The isotope measurement showed that the birds that had the good fortune to spend their first winter in the mangrove stayed in the good life, while the birds that had wintered in the dry area usually had a harder life year round.

The birds in the lush mangrove have access to more insects, which helps them maintain their weight, says Studds. This helps them to leave sooner on spring migration and arrive sooner in the more southern breeding areas, where spring is just beginning,

The birds in the dry area, however, need about another seven days to bulk up, a long time, says Studds. The later start means that by the time they head north, the southern breeding habitat is already taken and the birds have to keep flying, some as far north as Canada, to find the right spring conditions for breeding.

Where a redstart spends its first winter also seems to be determined, in part, by its ability hold its territory. About seventy percent of the birds in the mangrove are males, Studds says. In the harsh habitat, they were mostly females and young males.

Climate Change and the Redstart

While these redstarts appear to be thriving today, the research team says their findings point to the need to consider conservation measures in the winter habitat.

The models predict increasing drought in the Caribbean, says Studds. Rain is very important to these birds. If their winter habitat gets drier and their departure dates get later, populations in southern areas could see big declines.

The team next hopes next to research the redstarts breeding grounds. By analyzing isotopes in feathers of redstarts arriving to breed in Maryland, we plan to ask whether birds dispersing here from northern areas spent the winter in different habitats compared to birds dispersing from southern areas, Studds says.


'/>"/>

Contact: Ellen Ternes
eternes@umd.edu
301-405-4627
University of Maryland
Source:Eurekalert

Related biology news :

1. 60 second test could help early diagnosis of common brain diseases
2. Restless legs syndrome affects nearly 2 percent of US/UK children
3. Bleeding, not inflammation, is major cause of early lung infection death
4. Pig study sheds new light on the colonisation of Europe by early farmers
5. Color contrast is seen by the brain early doors
6. Extra gene copies were enough to make early humans mouths water
7. Was ability to run early mans Achilles heel?
8. New technique can be breakthrough for early cancer diagnosis
9. Yam bean a nearly forgotten crop
10. NIH awards nearly $23M to University of Chicago for translational research
11. Yam bean a nearly forgotten crop
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/3/2016)...  Neurotechnology, a provider of high-precision biometric identification ... Identification System (ABIS) , a complete system for ... can process multiple complex biometric transactions with high ... face or iris biometrics. It leverages the core ... MegaMatcher Accelerator , which have been used in ...
(Date:4/19/2016)... , UAE, April 20, 2016 ... be implemented as a compact web-based "all-in-one" system solution ... the biometric fingerprint reader or the door interface with ... of modern access control systems. The minimal dimensions of ... ID readers into the building installations offer considerable freedom ...
(Date:3/31/2016)... 2016   LegacyXChange, ... "Company") LegacyXChange is excited to release its ... to be launched online site for trading 100% guaranteed ... will also provide potential shareholders a sense of the ... an industry that is notorious for fraud. The video ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... 23, 2016 , ... Mosio, a leader in clinical research ... Recruitment and Retention Tips.” Partnering with experienced clinical research professionals, Mosio revisits the ... tools, and strategies for clinical researchers. , “The landscape of how patients receive ...
(Date:6/23/2016)... HOUSTON , June 23, 2016 ... agreement with the Cy-Fair Sports Association to serve ... of the agreement, Houston Methodist Willowbrook will provide ... education and connectivity with association coaches, volunteers, athletes ... partner with the Cy-Fair Sports Association and to ...
(Date:6/23/2016)... ... 23, 2016 , ... Supplyframe, the Industry Network for electronics ... Lab . Located in Pasadena, Calif., the Design Lab’s mission is to bring ... designed, built and brought to market. , The Design Lab is Supplyframe’s physical ...
(Date:6/23/2016)... LONDON , June 23, 2016 ... & Hematology Review, 2016;12(1):22-8 http://doi.org/10.17925/OHR.2016.12.01.22 ... Review , the peer-reviewed journal from touchONCOLOGY, ... the escalating cost of cancer care is placing ... a result of expensive biologic therapies. With the ...
Breaking Biology Technology: