Effect of blood parasites on secondary sexual characteristics and morphology in mountain white-crowned sparrows

Abstract

Blood parasites affect numerous species of birds across the world and can cause serious population declines. Haemosporidian blood parasites in Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha) are known to affect certain behavioral and morphological characteristics of hosts, including dominance-related characters like song. Blood parasites cause a host of symptoms, including anemia, reduced aerobic capacity, and increased metabolic demand. This study investigates the presence of various blood parasites and their influence upon crown-stripe width in males, a secondary sexual characteristic. According to the Hamilton-Zuk hypothesis, secondary sexual characteristics should be reduced in parasitized males and their breeding success consequently lowered. Birds were captured and processed at the Rocky Mountain Biological Laboratory, and for each bird a blood smear was taken as well as body measurements like tarsus, tail, and wing length. The presence of blood parasites Plasmodium, Haemoproteus, and Leucocytozoon were tested in relation to crown-stripe width, crown-stripe proportion, and tail, wing, and tarsus length. There was no significant effect of infection on crown-stripe width or proportion or wing and tarsus length, but there was a significant effect of Haemoproteus infection on increasing male tail length in males, and on Leucocytozoon x Plasmodium cross-infection on female tale length. This study warrants further research on effects of blood infections on morphological and behavioral phenotypes in Mountain White-crown sparrows, as climate change impacts vector populations and infection could increase in high- elevation areas.