• Growth, reproduction and diet of Roatan Spiny-tailed Iguanas, Ctenosaura oedirhina, with notes on the status of the species

      Pasachnik, Stesha A. (2013)
      Roatan Spiny-tailed Iguanas, Ctenosaura oedirhina, are listed as Endangered by the IUCN Redlist Assessment and under Appendix II of Convention on International Trade of Endangered Species of Wild Fauna and Flora (CITES). These iguanas occur primarily on Roatan and Barbaretta, off the Caribbean coast of Honduras. Habitat destruction associated with development, small-scale agriculture, and exploitation for food and the pet trade are contributing to the decline of these iguanas. This species was described in 1987 (de Queiroz) when it was split from the sister taxon C. bakeri, found on the island of Utila, Honduras. Since its description little has been done to understand its biology or protect this narrow-range endemic. Herein, I examined the morphology and body condition of this species across its range and report on its reproductive biology and diet. Similar to many members of the Iguaninae, males are larger on average and have relatively longer tails than females. Likewise, reproductive and dietary data are consistent with those for closely related species. The body condition of both males and females was lower in more pristine study sites, indicating that supplemental feeding in developed areas may be having an effect. A female-biased sex ratio was found in sites protected by grassroots efforts, where the populations were large enough to be studied. Conservation measures should focus on alleviating the threats of harvesting and habitat destruction through increased law enforcement, outreach, and education.
    • Mass loss rates of fasting polar bears

      Pilfold, Nicholas W.; Hedman, Daryll; Stirling, Ian; Derocher, Andrew E.; Lunn, Nicholas J.; Richardson, Evan (2016)
      Polar bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which polar bears must rely on fat reserves has increased....
    • Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity

      Rode, Karyn D.; Wilson, Ryan R.; Douglas, David C.; Muhlenbruch, Vanessa; Atwood, Todd C.; Regehr, Eric V.; Richardson, Evan S.; Pilfold, Nicholas W.; Derocher, Andrew E.; Durner, George M.; et al. (2018)
      The effects of declining Arctic sea ice on local ecosystem productivity are not well understood but have been shown to vary inter-specifically, spatially, and temporally. Because marine mammals occupy upper trophic levels in Arctic food webs, they may be useful indicators for understanding variation in ecosystem productivity. Polar bears (Ursus maritimus) are apex predators that primarily consume benthic and pelagic-feeding ice-associated seals. As such, their productivity integrates sea ice conditions and the ecosystem supporting them. Declining sea ice availability has been linked to negative population effects for polar bears but does not fully explain observed population changes. We examined relationships between spring foraging success of polar bears and sea ice conditions, prey productivity, and general patterns of ecosystem productivity in the Beaufort and Chukchi Seas (CSs). Fasting status (?7 days) was estimated using serum urea and creatinine levels of 1,448 samples collected from 1,177 adult and subadult bears across three subpopulations. Fasting increased in the Beaufort Sea between 1983–1999 and 2000–2016 and was related to an index of ringed seal body condition. This change was concurrent with declines in body condition of polar bears and observed changes in the diet, condition and/or reproduction of four other vertebrate consumers within the food chain. In contrast, fasting declined in CS polar bears between periods and was less common than in the two Beaufort Sea subpopulations consistent with studies demonstrating higher primary productivity and maintenance or improved body condition in polar bears, ringed seals, and bearded seals despite recent sea ice loss in this region. Consistency between regional and temporal variation in spring polar bear fasting and food web productivity suggests that polar bears may be a useful indicator species. Furthermore, our results suggest that spatial and temporal ecological variation is important in affecting upper trophic-level productivity in these marine ecosystems.
    • The influence of ambient noise on maternal behavior in a Bornean sun bear (Helarctos malayanus euryspilus)

      Owen, Megan A.; Hall, S.; Bryant, L.; Swaisgood, Ronald R. (2014)
      …Here we correlate behavioral and vocal patterns in a Bornean sun bear (Helarctos malayanus euryspilus ) mother and cub with ambient noise levels during the 6‐month post‐partum period. We hypothesized that loud ambient noise would be correlated with changes in behavior, and predicted that noise would be negatively correlated with maternal care behavior, potentially masking cub vocalizations or providing a distraction to the mother….