Mind the gap: treefalls as drivers of parental trade-offs

Tree-fall gaps are small-scale disturbances whose formation, colonization, and role in forest dynamics are well documented, but whose effects on animal ecology are still greatly overlooked, except for studies comparing species richness of gaps 6+ months old to that in the closed canopy. Other factors associated with the invasion of fresh tree-fall gaps such as animal breeding adaptations have been largely neglected. I studied the immediate (within hours and days) arrival of the poison frog Dendrobates tinctorius in new tree-fall gaps to examine the dynamics of their invasion in relation to tadpole rearing. I found that rearing sites are occupied sooner and tadpoles deposited at higher rates in fresh gaps than in the closed forest, but that the rate of cannibalism is also much greater in the former. This suggests that invading new tree-fall gaps can be the best parental decision when parents arrive early because they get access to fresh, high-quality resources, but it could be to the detriment of the offspring if parents arrive late, because of overcrowding and cannibalism. These results highlight the importance of studying the earliest stages of invasions in order to have a better understanding of the composition of communities in disturbed ecosystems at later successional stages. Habitat disturbances may enable the exploitation of resources previously unavailable. Dyeing poison frogs invade fresh treefall gaps as soon as they form, presumably in part searching for tadpole rearing sites. This study shows how the benefits of a new resource available may trade-off with the costs of crowding and over-use.