Nest Survival

Spruce Grouse (Falcipennis canadensis) are listed as threatened in Wisconsin, and the boreal habitats in which they occur are likely to be threatened by changing climatic conditions. However, the limited information available on Spruce Grouse in the Upper Great Lakes region makes it unclear which habitat features are important for Spruce Grouse nesting in Wisconsin. We radiotracked 30 female Spruce Grouse in northern Wisconsin from 2007–2012 and located 25 nests. Eighteen of 25 nests were beneath black spruce (Picea mariana) trees. Only three nests were in upland, and only one in a stand of jack pines (Pinus banksiana), in contrast to studies from Michigan and Ontario. Overall concealment was a good predictor of nest sites for Spruce Grouse, but not a good predictor of nest survival. Nest survival was associated with moderately dense and uniform 0–0.5 m lateral vegetation cover. Seventeen of 25 nests were successful, with a daily survival rate of 0.985, overall productivity of 1.0 young/female, and 1.9 young/successful nest. Annual survival of adult males was estimated at 54%, adult females at 40%, and juvenile survival at 14% and 24% by two different methods. Estimates of l of 0.65 and 0.67 suggest a declining population, but the upper confidence limit exceeds 1, not ruling out a stable or slightly increasing population. Protecting black spruce swamps will protect important nesting habitat for Spruce
Grouse in Wisconsin.

1.Demographic consequences of human-induced rapid environmental change (HIREC) have been widely documented for many populations. The mechanisms underlying such patterns, however, are rarely investigated and yet are critical to understand for effective conservation and management.

2.We investigated the mechanisms underlying reduced avian nest survival with intensification of natural gas development, an increasing source of HIREC globally. We tested the hypothesis that energy development increased the local activity of important nest predator species thereby elevating nest predation rates. During 2011–2012, we surveyed predators and monitored 668 nests of Brewer's sparrows Spizella breweri, sagebrush sparrows Artemisiospiza nevadensis and sage thrashers Oreoscoptes montanus breeding at twelve sites spanning a gradient of habitat loss from energy development in western Wyoming, USA.

3.Nine species, representing four mammalian and three avian families, were video-recorded depredating eggs and nestlings. Important nest predator species differed across songbird species, despite similar nesting habitats. Approximately 75% of depredation events were by rodents.

4.Consistent with our predictions, detections of most rodent nest predators increased with surrounding habitat loss due to natural gas development, which was associated with increased probability of nest predation for our three focal bird species.

5.An altered nest predator assemblage was therefore at least partly responsible for elevated avian nest predation risk in areas with more surrounding energy development.

6.Synthesis and applications. We demonstrate one mechanism, i.e. the local augmentation of predators, by which human-induced rapid environmental change (HIREC) can influence the demography of local populations. Given the accelerating trajectory of global energy demands, an important next step will be to understand why the activity and/or abundance of rodent predators increased with surrounding habitat loss from energy development activities.

We estimated nest survival and evaluated factors affecting this demographic parameter for the Black Catbird (Melanoptila glabrirostris), a poorly known mimid endemic to the Yucata´n Peninsula. During the 2008 and 2009 breeding seasons, we monitored 136 nests spread across four sites in Mexico, including three mainland coastal sites in the Sian Ka’an Biosphere Reserve and one site on Cozumel Island. We documented higher nest loss in the mainland sites (74 % failed) in contrast to the island site (21 % failed). Based on our observations, we suspect that predation was the main cause of nest failure. Using logistic exposure models and Akaike’s Information Criterion, we found date, nest age, and nest type to be the main factors influencing nest survival. Nest survival was lower for open cup-nests in comparison with semi-cavity nests. Interval nest survival (proportion of nests expected to survive the entire nesting season) was 0.102 (CI = 0–0.660) for open-cup nests and 0.618 (CI =0–0.98...