The role of supplementary feeding in conferring pathogen tolerance

Feeding of wildlife by humans is a hugely popular activity, yet we still know little about the consequences for wildlife.

I recently showed that provisioned birds exhibited an attenuated fever response to a simulated infection, suggesting they are more tolerant of infection.

With this proposal, I will investigate how provisioned wild great tits Parus major can mitigate the costs of infection via changes in physiology and behaviour.

Using manipulations of food provisioning in the wild and triggering birds’ immune defences with endotoxin, I will test the hypotheses that birds that use feeders more acquire higher tolerance and, using social network analysis, that “well-connected” birds become more tolerant.

If birds are repeatedly exposed to mild infection at bird feeders, suppressing fever and sickness behaviours (e.g. lethargy, anorexia) could be beneficial by limiting excess damage to the body caused by the host’s own immune defences (i.e. tolerance). By removing feeders for some birds, I will determine how access to feeders while sick alters behaviour.

If feeding enables birds to continue to be healthy and active while sick, it may increase their survival, but increase transmission of pathogens and could lead to them becoming superspreaders of disease.

Given that the risk of infection to wildlife is expected to increase with accelerating anthropogenic change, it is pertinent to understand how supplementary feeding can confer tolerance and influence future disease outbreaks.