The impact of live trapping and trap model on the stress profiles of North American red squirrels

Abstract

Live‐capture is a necessary component for the scientific study and management of most mammals, but it may negatively affect their health and physiology. We compared blood parameters related to the stress response (nominal base levels) from red squirrels Tamiasciurus hudsonicus after capture of up to 4.5 h in five different live trap models (Hava‐hart, Sherman, Tomahawk 102, Tomahawk 103 and ‘Special Squirrel’ trap) with true base levels (obtained in less than three minutes). In addition, we evaluated the capture rate in the five trap models. We found that (1) prolonged time in live traps altered stress hormone concentrations compared with true base levels, but maximum corticosteroid‐binding capacity was unaffected; (2) squirrels captured in a trap model with reduced visibility (a roof cover – Hava‐hart) had significantly lower (c. 50%) mean free cortisol levels compared with those captured in a trap model with full visibility (Tomahawk 102), but all other blood parameters were similar; (3) cortisol levels and white blood cell counts (mainly neutrophil counts) were positively related to duration of capture; (4) a non‐covered trap (Tomahawk 102) was most effective and fully covered trap (Sherman) was least effective at capturing squirrels. We discuss the use of effective, yet less stress‐inducing trap models to mitigate the stress caused by live‐capture on these animals. We conclude that covered traps such as the Hava‐hart may reduce trap‐induced stress in red squirrels, but at the same time also reduces their capture rates.

Assessing the impact of live-capture, confinement, and translocation on stress and fate in eastern gray squirrels

“…To estimate baseline stress levels using FCM, trap-check frequency should be shorter than the lag for the appearance of FCM in the feces, because trapping and handling can increase plasma glucocorticoids levels (Bosson et al 2012). A 2nd precaution from our results is that feces should not be collected from the same animal within a 3-day window, because the stress of the 1st capture might influence FCM levels at the 2nd capture.…”

Short-term effects of tagging on activity and movement patterns of Eurasian beavers (Castor fiber)

“…Certainly, shortened handling periods appear to help mitigate stress (e.g. Bosson et al 2012;Ponjoan et al 2008). Even though some studies claim that using chemical immobilization reduces capture and handling stress (Montané et al 2002;Read et al 2000), we argue that not using anaesthesia can be an advantage: Our procedure meant that beavers were released immediately back into their familiar surroundings (including lodges and burrows for refuge) without adverse affects from anaesthesia and/or surgery.…”

“…blood parameters and/or faeces; Bosson et al 2012;Harcourt et al 2010;Rehnus et al 2009;Sheriff et al 2011). Indeed, capture effects might only be physiological (Kock et al 1987;Meyer et al 2008) and do not necessarily imply visible behavioural changes.…”

Anthropogenic food provisioning and immune phenotype: Association among supplemental food, body condition, and immunological parameters in urban environments

“…Neutrophil:lymphocyte (N:L ratio) was also calculated as an index of stress in each individual. Based on the effect of corticosteroid stress hormone on reducing number of lymphocyte while increasing neutrophils in multiple vertebrate taxa, N:L ratio is considered a reliable marker for glucocorticoid levels (Davis, Maney, & Maerz, 2008) and has been applied in previous studies as index of stress (Bosson, Islam, & Boonstra, 2012;Johnstone, Lill, & Reina, 2012). We measured two humoral immune parameters: the bacterial killing assay (BKA) and total immunoglobulin G (IgG) concentration as indicators of innate and adaptive immune defenses, respectively (Lee, 2006;Schneeberger, Courtiol, Czirják, & Voigt, 2014).…”