On a beautiful Tuesday morning in April, I got up early and headed to rare to join PhD student Leanne Grieves for a fruitful morning of field work. Leanne is studying Song Sparrows, Melospiza melodia, at the University of Western Ontario under the supervision of Dr. Beth MacDougall-Shackleton. Her research examines the relationship between haematozoan parasites, immune defenses, and mate choice in breeding Song Sparrows.
Haematozoan parasites are blood parasites that cause avian malaria and can have negative effects on the fitness of infected hosts. Due to a changing climate and the high mobility of migratory species, it is important to understand the relationships between hosts and parasites, particularly as it relates to grassland nesting birds, which suffer from additional stresses such as habitat loss due to development and agriculture. Understanding these relationships in one species will hopefully help us to understand them in others, and this knowledge is particularly important for making conservation and management decisions when protecting species at risk.
I met Leanne at 7:15 am, just in time to check the traps she had set up with the hopes of capturing Song Sparrows. At each trap, we checked to see what was inside, and if it was a Song Sparrow, Leanne set up her kit and took a variety of measurements to support her research. In addition to standard measurements of size, weight and fat storage, blood samples and preen oil were collected, and birds were banded so that Leanne could identify and track individuals after their release.
Once back in London, Leanne will process the blood samples and identify the presence and species composition of parasites. At rare, she conducted an experiment using the preen oil samples she collected in the field to determine whether birds prefer mates with dissimilar MHC genotypes. MHC is an important gene family that has evolved for immune defense in vertebrates, likely in response to pathogens. Leanne is trying to determine whether birds select mates that are genetically dissimilar; if birds that are MHC dissimilar mate, it would increase the diversity the MHC genotypes in their offspring, and possibly the ability of birds’ immune systems to successfully fight off parasites and other pathogens. If mates select for such diversity, it could mean a healthier and more disease-resistant population of birds!
In the rare lab, preen oil samples of one sex were presented to known Song Sparrows of the opposite sex, and the amount of time birds spent with each preen oil sample was recorded, with the assumption that birds spend more time with the preferred preen oil sample. Preen oil preference will be compared to genetic information to determine whether Song Sparrows are selecting for MHC-dissimilar mates. Leanne will use the results of her study at rare in combination with data collected at two other sites in Ontario to answer her research questions, and will be back at rare to collect more samples in the future.
Leanne informed me that the morning I joined her was the most productive to date (in terms of number of birds caught) , and I feel so lucky that I was able to experience such a peaceful and fascinating morning in Blair Flats with Leanne, the sparrows, and the rest of nature along the Grand River. I always forget how full of life mornings are until I am reminded by great experiences like this.
By: Allie Abram