Blood parasite infection linked to condition of spring-migrating Lesser Scaup (Aythya affinis)

Abstract

Numerous organisms exhibit carry-over effects, in which previous environmental conditions impact current performance. For example, reproductive output for many migratory birds can be impacted by events during the preceding migration. Lesser Scaup (Aythya affinis (Eyton, 1838); hereafter scaup) declined dramatically during 1970s–2000s, and there is evidence linking reduced reproductive output to reduced body condition during spring migration. In addition to food availability and quality, haemosporidian parasites (Plasmodium spp., Haemoproteus spp.) may be associated with condition of spring-migrating birds. We examined whether haemosporidian parasite infection status was linked to measures of size (mass, wing length, tarsus length, and keel length) and condition (body fat, size-corrected mass, wing-loading) in female spring-migrating scaup. Infection prevalence varied by year (21.7% in 2014; 47.1% in 2015) and percent body fat was negatively associated with the probability of infection. Body fat levels declined from 2014 to 2015, but at a similar rate for infected and uninfected birds. This pattern suggests that the increased prevalence in 2015 may have been related to the greater proportion of poor-condition birds being more susceptible to infection or recrudescence of latent infections. In light of forecasted range shifts and expansions of avian malaria vectors, the impact of haemosporidian parasites on migratory waterfowl condition warrants further investigation.

Host phylogeny matters: Examining sources of variation in infection risk by blood parasites across a tropical montane bird community in India

“…With individual body condition, we expected to nd low probability of infection in birds with better condition because generally, parasitic infections negatively affect host body condition [20,27,85]. Hosts in poor body condition are likely more susceptible to infection due to reduced immunocompetence [4,86,87]. Contrary to our expectations, we found no signi cant association between host body condition and Plasmodium infection and a positive effect of body condition on the probability of Haemoproteus infection.…”

Host phylogeny matters: Examining sources of variation in infection risk by blood parasites across a tropical montane bird community in India

“…With individual body condition, we expected to nd low probability of infection in birds with better condition because generally, parasitic infections negatively affect host body condition [20,27,88]. Hosts in poor body condition are likely more susceptible to infection due to reduced immunocompetence [4,89,90]. Contrary to our expectations, we found no signi cant association between host body condition and Plasmodium infection and a positive effect of body condition on the probability of Haemoproteus infection.…”

Host phylogeny matters: Examining sources of variation in infection risk by blood parasites across a tropical montane bird community in India

“…With individual body condition, we expected to find low probability of infection in birds with better condition because generally, parasitic infections negatively affect host body condition [ 20 , 27 , 88 ]. Hosts in poor body condition are likely more susceptible to infection due to reduced immunocompetence [ 4 , 89 , 90 ]. Contrary to our expectations, we found no significant association between host body condition and Plasmodium infection and a positive effect of body condition on the probability of Haemoproteus infection.…”