Effects of repeated investigator handling of Leach's Storm-Petrel chicks on growth rates and the acute stress response

Abstract

Disturbance during development may have lasting effects on the growth rates and stress physiology of birds. Although repeated handling by researchers is often necessary, the possible effects of such handling on the development of semi‐altricial young are unclear. We examined the effect of daily handling on growth rates and plasma corticosterone levels of Leach's Storm‐Petrel (Oceanodroma leucorhoa) chicks on Kent Island in the Bay of Fundy, New Brunswick, Canada, during the 2011 nesting season. From post‐hatch day 7 to post‐hatch days 14–36, birds in the experimental group were extracted from burrows and measured (wing, tarsus, and mass) for ∼3 min every day, whereas birds in the control group were left undisturbed. After the treatment period, blood was collected from birds in both groups within 3 min of initially reaching into burrows (baseline) and after a 30‐min restraint stress test to assess the effect of early life disturbance on programming of the hypothalamic‐pituitary‐adrenal (HPA) axis. A second acute restraint stress test was conducted three weeks after the end of the treatment period to investigate possible longer term effects of early life disturbance. Growth rates of wings and tarsi were similar for handled chicks (N = 18) and non‐handled control chicks (N = 21), as were baseline and 30‐min acute restraint stress‐induced corticosterone levels. As also reported in previous studies of other altricial and semi‐altricial species, older chicks (42–64 d old) had higher plasma corticosterone levels than younger chicks (21–43 d old) after acute restraint stress tests, reflecting delayed development of the HPA axis. The age‐related increase in HPA axis sensitivity observed prior to fledging could facilitate foraging and predator avoidance behaviors while minimizing exposure to high levels of corticosterone earlier in development. Overall, we found no evidence that repeated disturbance influenced either growth rates or HPA axis programming of Leach's Storm‐Petrel chicks.

Apparent survival of adult Leach’s Storm-petrels (Oceanodroma leucorhoa) breeding on Bon Portage Island, Nova Scotia

“…Something to be cognizant of in survival and other CMR studies is investigator disturbance, which can influence reproductive success and potentially lead to nest abandonment (Blackmer et al 2004, Carey 2009but see O'Dwyer et al 2006, Fiske et al 2013. Burrows on Bon Portage Island were visited only twice during incubation, which should be associated with infrequent abandonment (Blackmer et al 2004).…”

Assessing the effects of repeated handling on the physiology and condition of semi‐precocial nestlings

“…, Fiske et al . ). It is probably maladaptive for cavity‐dwelling chicks, such as those of Storm Petrels, which are unable to escape or defend themselves in the event of a predation attempt, to elicit an adrenocortical response to an acute stressor.…”

“…Despite being capable of eliciting an adrenocortical response to a standardized stressor (albeit somewhat reduced compared to adults), Fiske et al . () demonstrated that daily handling had no effect on either baseline or stress‐induced CORT levels or growth rate in nestlings of the Leach's Storm Petrel. Not only was handling at a high intensity (daily) in this study, but it was also confined to the first half of postnatal development (maximum of 29 days post‐hatch).…”

Effects of human disturbance on postnatal growth and baseline corticosterone in a long-lived bird

“…While it is not certain if nestling storm petrels can elicit an acute adrenocortical response to a stressor, the young of related species have been shown to exhibit a robust acute stress response shortly after hatching, albeit greatly reduced compared with adults ( Adams et al , 2008 ; Fiske et al , 2013 ; Quillfeldt et al , 2009 ). Such hyposuppression of the HPA axis has been demonstrated in many vertebrates and is assumed to be adaptive, by preventing exposure to excess GCs during the vulnerable period of development ( Wada et al , 2007 ).…”