Research Interests

Currently I have two major areas of research, blood parasites of birds and a long term study of a Gray Jay (Perisoreus canadensis). 

Birds are host to five major types of blood parasites.  Leucocytozoon, Plasmodium, and Haemoproteus are sometimes referred to as bird malaria. The are protozoan parasites of the blood cells of birds.  Trypanosomes are protozoa that live in the liquid portion of the blood.  The fifth type is microfilarial worms, an embryonic form of a large nematode worm.  It discharges its hatched eggs into a blood vessel where they circulate.  All these blood parasites use an insect vector to transmit the disease.

Trypanosome from a Blue Jay

I have looked at nearly 3000 blood smears from 57 species of birds.  The study is unique in that they were all caught in my back yard, here in Northfield, VT over a 25 year period.  Some of the birds are much more likely to have parasites than others.  For instance, Black-capped Chickadees were only infected 9% of the time whereas American Robins have an 88% infection rate.  There are many reasons for such a disparity.  Vector abundance in those habitats used by the birds is probably the most likely reason, however the strength of the immune system might be involved also.

In 1991, the Vermont Fish and Wildlife Department contracted me to look at Gray Jays in Vermont.  We were anxious to learn whether this species was a candidate for listing as Threatened or Endangered.  I began to trap and band these birds.  Each bird was provided with a unique set of colored leg bands in addition to the US Fish and Wildlife Service metal band.

Banded Gray Jay

Gray Jay with unique series of color bands

I have continued to study this bird since that time.  My students and I have used radio telemetry to track the movements of the birds to determine how large an area it needs.  Another student has recorded the calls of the Gray Jays and used a bioacoustics program, Raven, to analyze their sounds.  Recently, I have begun to take blood samples from each bird.  With it I can sex the birds, a problem that had slowed down my research for some time.  Using the DNA we extract from the blood I hope to learn more about the genetics of the Gray Jays at Victory Bog, Vermont.

Other topics that my students and I have researched are the distribution and abundance of freshwater sponges in central Vermont.  Sponges are identified by the presence of certain spicules and their morphology.  I was skeptical of this procedure.   Tim Blood and Emily Poulin were awarded summer research grants to look at the genetics and ecology of these sponges.  Extracting their DNA, Tim and Emily sequenced the DNA and concluded that in the majority of cases, spicule analysis was valid in identifying species.  He did have some specimens that keyed out to a species but did not group within that species.  So more work still needs to be done. 

Last summer a student used a PCR protocol to search for Batrachochytrium dendrobatidis  (Bd).  This fungus has spread rapidly around the globe since its discovery a decade ago.  It has been implicated in the severe population decline of some frog species.  Hunter Twombly looked for evidence of the disease in salamanders.  He spent the summer collecting salamanders, swabbing their skin, and using PCR to identify the fungus.  We did not find any evidence of the disease here in Vermont.

This summer, two of my students have applied for a research fellowship to do a survey of turbellaria (“planaria”) in Vermont.  One will concentrate on streams and the other will look in ponds.  This group of freeliving flatworms is poorly studied.

A listing of student research projects I have mentored are included on the Student Research page.

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