A retrospective insight into the potential effects of parasites on the eastern loggerhead shrike (Lanius ludovicianus spp.) captive-breeding program in southeastern Canada

Abstract

Recovery programs around the globe attempt to mitigate the current biodiversity crisis. Captive breeding programs (CBPs) are one of the tools to attempt conserving diverse threatened or endangered species. This study investigates the CBP of an endangered passerine species in southeastern Canada, the eastern loggerhead shrike (Lanius ludovicianus spp.; ELOSH) in the context of one of the most common sanitary challenges in captivity: parasitic infections. Endoparasites can cause damage directly and/or indirectly and may lead to restriction of growth and reproductive functions of their host. This thesis objective is to draw attention to the importance of host-parasite interactions in captive-breeding settings, as well as study the potential effects on breeding success, by collection and analysis of historical data. Two separate datasets were used to conduct the statistical analysis (1) one to describe the parasitic prevalence and abundance, and its effects on the captive population, and (2) another to examine the effects of such parasites in the reproductive output of ELOSH females. Male-biased and juvenile-biased parasitism were observed among the individuals parasitized by Capillaria sp. In females, the abundance of Capillaria sp. was the only significant factor negatively affecting their reproductive output. Altogether, the results highlight the importance of parasitic management in CBPs, especially for endangered species, where it is essential to prevent any further threats to an already scarce population.