Press Releases

BIRD ENTHUSIASTS INVITED TO HELP WITH HOUSE FINCH NEST SURVEY

Cornell Reseachers Studying Reasons for House Finch Disease Fluctuations

May 12, 2004

Spring 2004, Ithaca, NY - In 1994, bird watchers began to notice House Finches with swollen, crusty eyes and reported their sightings to the Cornell Lab of Ornithology. In response, the Lab created the House Finch Disease Survey (HFDS), which tracked the disease, mycoplasmal conjunctivitis, as it moved through House Finch populations. Now a new study from the Lab, called the House Finch Nest Survey (HOFINS), funded by the National Science Foundation, is supplementing the disease survey.

    "The HFDS found seasonal variation in the prevalence of mycoplasmal conjunctivitis. Birds infected with the disease are rare during the breeding season, but there is an increase in disease prevalence at the end of the summer, a peak in autumn, a midwinter decline, a springtime increase, and a return to breeding-season lows," says Melanie Driscoll, coordinator for the House Finch Nest Survey. In addition, she says, this pattern varies latitudinally¿the autumn peak comes earlier in the South, and the disease rate is higher there as well. If the House Finch Nest Survey receives enough data about House Finch reproduction, Lab researchers may be able to determine the reasons for this variable pattern.

    According to mathematical models developed by Lab researchers, in collaboration with a Princeton University scientist, the longer breeding season in the South could be a factor influencing the pattern¿a longer breeding season may allow for more nesting attempts, which in turn could result in more young being produced. Also of note is the fact that juveniles are more susceptible to mycoplasmal conjunctivitis, and these young birds tend to flock together during the fall. This could explain the leap in prevalence of this disease, which is highly contagious among House Finches. But why the midwinter drop and springtime rise? Researchers need data to help them find this out.

    To get that data, Lab researchers are again turning to bird enthusiasts across North America. Participants in the House Finch Nest Survey locate House Finch nests and keep track of egg-laying, hatching, and fledging dates. Detailed information and images are provided to help participants determine the age of nestlings in case they miss the hatching event. Volunteers are also asked to note the presence of Brown-headed Cowbird eggs. Cowbirds are brood parasites, which means female cowbirds lay their eggs in other birds' nests, including those of House Finches, and the cowbird young often outcompete the host bird's own babies for food. Participants provide their data to Lab researchers on paper Nest Record Cards. Detailed instructions and Nest Record Cards are included in the Research Kit provided to participants when they sign up.

    Also included in the Research Kit are tips for finding House Finch nests. "House Finches are interesting and relatively easy birds to study because of where they nest," says Driscoll. "They choose to associate with humans, so their nest sites may include hanging plants, wreaths on doors, windowsills, eaves in barns and garages; they've even been known to nest on tractor radiators. "She adds that in the West, where they are native (House Finches were introduced in the eastern United States around 1940), the birds are more apt to use natural nest sites such as citrus trees and cholla cacti.

    To locate nests, Driscoll says to watch where birds carry nesting material and to be on the lookout for singing males who may be trying to attract females to a good nest site. She says providing a bird feeder is a good way to entice birds to nest in your yard. Because of their preference for nesting near humans, House Finches are more tolerant of disturbance than are most species, but tips are provided nonetheless on how to check nests safely and efficiently, to minimize disturbance to the nest.

    The Research Kit is also very clear about what not to do. For example, participants are instructed not to check nests during cold, damp, or rainy weather, and are told to never, under any circumstances, touch nests, eggs, or nestlings.

    People of all skill levels are invited to participate in the House Finch Nest Survey. By signing up, these "citizen scientists" become part of a nationwide research team that will help researchers learn more about birds, the factors that influence their breeding success, and the resulting impact on prevalence of mycoplasmal conjunctivitis. To find out more about the study or to sign up, contact the Lab at (800) 843-2473 in the United States; (607) 254-2473 in Canada. Visit the House Finch Nest Survey web site at www.birds.cornell.edu/hofi.

The Cornell Lab of Ornithology is a nonprofit membership institution interpreting and conserving the earth's biological diversity through research, education, and citizen-science focused on birds.