Regular handling reduces corticosterone stress responses to handling but not condition of semi-precocial mottled petrel (Pterodroma inexpectata) chicks.

Handling of avian study species is common in ecological research, yet few studies account for the impact of handling in nestlings where exposure to stress may result in negative lifetime fitness consequences. As a result, our understanding of stress reactivity in free-living avian young is limited. In this study we examined the cumulative impact of three levels of research-relevant handling (control, daily and every three days) on the development of the stress response, growth and condition of semi-precocial seabird chicks from near-hatching to near-fledging. By measuring corticosterone concentrations in plasma, we found that mottled petrel (Pterodroma inexpectata) chicks were capable of mounting a stress response comparable to adults from near-hatching. There were no differences in plasma corticosterone concentrations in initial samples (<4 min) between groups at six weeks of age, though by 12 weeks of age plasma corticosterone concentrations in initial samples collected from chicks handled daily were lower than chicks that were handled once every three days, and from control chicks. Corticosterone responses to handling were lower in chicks handled daily at six and 12 weeks of age when compared to other handling groups. Handling chicks daily or every three days had no negative effect on the growth or condition of chicks when compared to control chicks. These findings indicate that daily handling results in chicks became accustomed to handling, with no evidence that regular handling was detrimental to mottled petrel chicks. However, given the unique life-history characteristics of mottled petrels relative to closely related species, we caution that this finding may be species-specific, and wider testing is recommended.

From islands to infectomes: host-specific viral diversity among birds across remote islands.

BACKGROUND: Accelerating biodiversity loss necessitates monitoring the potential pathogens of vulnerable species. With a third of New Zealand's avifauna considered at risk of extinction, a greater understanding of the factors that influence microbial transmission in this island ecosystem is needed. We used metatranscriptomics to determine the viruses, as well as other microbial organisms (i.e. the infectomes), of seven bird species, including the once critically endangered black robin (Petroica traversi), on two islands in the remote Chatham Islands archipelago, New Zealand. RESULTS: We identified 19 likely novel avian viruses across nine viral families. Black robins harboured viruses from the Flaviviridae, Herpesviridae, and Picornaviridae, while introduced starlings (Sturnus vulgaris) and migratory seabirds (Procellariiformes) carried viruses from six additional viral families. Potential cross-species virus transmission of a novel passerivirus (family: Picornaviridae) between native (black robins and grey-backed storm petrels) and introduced (starlings) birds was also observed. Additionally, we identified bacterial genera, apicomplexan parasites, as well as a novel megrivirus linked to disease outbreaks in other native New Zealand birds. Notably, island effects were outweighed by host taxonomy as a significant driver of viral composition, even among sedentary birds. CONCLUSIONS: These findings underscore the value of surveillance of avian populations to identify and minimise escalating threats of disease emergence and spread in these island ecosystems. Importantly, they contribute to our understanding of the potential role of introduced and migratory birds in the transmission of microbes and associated diseases, which could impact vulnerable island-endemic species.