While many diseases in wild animals are difficult if not impossible to study,
an apparently novel disease appeared in the vicinity of Washington, DC in the winter of
1993-94. The disease is caused by a previously unknown strain of
Mycoplasma gallisepticum, a bacterium that typically causes respiratory
infections in domestic poultry and is found world-wide. This new strain of the
bacterium appears highly specific to House Finches (Carpodacus mexicanus),
only occasionally infecting other species of finches. Click on the link to
find more information about the disease, to learn about our research project, the
House Finch Disease Survey, and to
find out how you can help.
This new disease, while unfortunate for the birds, provided researchers with
a unique opportunity to study the effects of a disease on a population of wild
animals. Several factors contributed to our being able to conduct this unique
study:
- Disease Symptoms Easily Observed Mycoplasma gallisepticum
causes House Finches to develop eye inflamations (a condition termed
"mycoplasmal conjunctivitis") that in some cases result in
the bird's eyes being swollen shut. These symptoms are easily observed and
can be used to identify infected birds. This eliminates the need for costly
and time-consuming laboratory analyses.
- House Finches and Disease Found Over Large Area Scientists
typically repeat experiments or observations on different study animals in order
to determine whether patterns are consistent. Repeated observation of the
same patterns gives researchers confidence that there results are not a random
accident. The wide distribution of House Finches (which includes much of the
southern half of North America) allowed us to divide the eastern half of North
America into separate areas and to determine whether the same results were
seen in each area.
- Long History of Monitoring House Finches In order to find out
how many birds die as a result of a disease, we need to know the abundance of
birds before the disease arrived. For House Finches, this information is
available thanks to projects such as the Christmas Bird Count and Project
FeederWatch.
- Disease Not Deliberately Introduced In general, the effects of
diseases are only studied well (we know how many animals were present
before the disease arrived) for diseases that are deliberately introduced
to lower population sizes of animals considered pests. These diseases are
deliberately chosen for their ability to kill target animals. Such diseases
do not represent a typical effect of a disease.
- Project FeederWatch Only months after the first reports of
mycoplasmal conjunctivitis, we were able to begin collecting data. This was only
possible because participants in Project FeederWatch were already observing
infected birds and were willing to report their information to the House Finch Disease
Survey. Because participants in Project FeederWatch are found across the
U.S. and Canada, we are able to survey the entire continent and continue to
follow the spread of the disease.