Ethogram describing different types of aggressive interactions observed for <i>Atelopus</i>.

<p><b>Fight</b>: Combat involving mouth or front limbs, often flipping of opponent; <b>Mount</b>: >50% of initiators body covers the victim for >5 seconds; <b>Release call</b>: High pitched, weak, peep like call; maximum tally of one per individual; <b>Physical contact</b>: Any remaining forms of physical contact; <b>Stalk</b>: One individual actively follows/chases another for >5 seconds; <b>Wave</b>: Circular movements in front limbs.</p

Fecal glucocorticoid concentrations immediately before and after male <i>Atelopus</i> were grouped together at week 1 (ng cortisol/g ± SEM) changed significantly over time (p = 0.04*), but there were no significant differences between groups sizes (A).

<p>Frogs housed singly (mean  = 44.2 ng cortisol/g±7.4 SEM) could not be included in this analysis because of too many missing values. Aggressive interactions changed significantly over time (p<0.001***), but there were no significant differences between group sizes.</p

Cortisol EIA profile (black, diamond marks) and Corticosterone RIA profile (grey, triangle marks), in <i>Atelopus</i> feces following an ACTH challenge (0.2 IU, IM).

<p>Cortisol EIA profile (black, diamond marks) and Corticosterone RIA profile (grey, triangle marks), in <i>Atelopus</i> feces following an ACTH challenge (0.2 IU, IM).</p

Repeated measures ANOVA testing the effects of time (weeks 0–4) and group size on fecal glucocorticoid levels in <i>Atelopus</i> housed together (groups of 8 vs 2).

<p><i>(</i><b><i>a</i></b><i>). We omitted group size n = 1 from the analysis because there were too many missing values to run statistical comparisons. Repeated measures ANOVA testing the effects of time (weeks 1–4) and group size (8 vs 2) on aggressive interactions in Atelopus housed together (</i><b><i>b</i></b><i>).</i></p

Evaluating group housing strategies for the ex-situ conservation of harlequin frogs (Atelopus spp.) using behavioral and physiological indicators

We have established ex situ assurance colonies of two endangered Panamanian harlequin frogs, Atelopus certus and Atelopus glyphus, but observed that males fought with each other when housed as a group. Housing frogs individually eliminated this problem, but created space constraints. To evaluate the potential stress effects from aggressive interactions when grouping frogs, we housed male frogs in replicated groups of one, two, and eight. We measured aggressive behavioral interactions and fecal glucocorticoid metabolite (GC) concentrations as indicators of stress in each tank. In both small and large groups, frogs initially interacted aggressively, but aggressive interactions and fecal GCs declined significantly after the first 2 weeks of being housed together, reaching the lowest levels by week 4. We conclude that aggressive interactions in same-sex groups of captive Atelopus may initially cause stress, but the frogs become habituated within a few weeks and they can safely be housed in same-sex groups for longer periods of time