Previous research has demonstrated the importance of nest predation as a major force affecting the reproductive success of birds. The evolution of different life histories, reproductive strategies, and habitat selection in response to predation has been well- documented across avian taxa. However, no studies have focused on a cavity-nesting species with a low reproductive rate. I investigated how the Flammulated Owl (Psiloscops flammeolus), a small secondary cavity-nesting raptor, has adapted in response to predation by the North American Red Squirrel (Tamiasciurus hudsonicus) on the Manitou Experimental Forest in Central Colorado. I evaluated several mechanisms of predator avoidance that Flammulated Owls may have evolved as part of their nest habitat selection, including selecting locations with lower squirrel density or lower squirrel activity, and selecting nesting locations that limit attacks by squirrels. I estimated squirrel density from detections along line transects, mapped locations of squirrels that were detected, and mapped the location of squirrel middens within and outside owl territories. Habitat variables were quantified at owl nest trees and adjacent forests and compared to available but unused sites. I found that squirrel density per hectare was greater in owl territories (3.1 ± 0.4) than random territories (0.3 ± 0.1; t=6.1, df=2, p<0.05), but I found no correlation between squirrel abundance and midden characteristics. Cavity height was on average higher at owl nests (7.7 ± 0.2m) than available but unused cavities (6.0 ± 0.3m; t=2.7, df=369, p<0.01), and successful nests (8.9 ± 0.4m) were higher than depredated nests (6.6 ± 0.3m; t=4.1, df=69, p<0.001). A similar pattern was found with nest tree height, and a positive correlation was found between the two habitat characteristics (p<0.001, R2=0.26). Although squirrel density was higher in owl territories, it is possible that underlying habitat differences exist across the study area, and that common characteristics are associated with high-quality habitat for both owls and squirrels. Selection for higher nesting cavities by Flammulated Owls may be an adaptive response to perceived predation risk or decreased nesting success in lower cavities, as has been corroborated by other studies of cavity-nesting birds.
For the last ten years, the words ‘sustainability’ and ‘sustainable development’ have been used by many prominent political and economic leaders. But what is sustainability really and is it possible to accurately measure the sustainability of countries’ economies objectively? This study focuses on three sustainability models, namely the Environmental Sustainability Index (ESI), the Sustainability Assessment by Fuzzy Evaluation (SAFE) and the Sustainable Human Carrying Capacity (SHCC), and their evaluations on the sustainability of the Hungarian economy and environment. Furthermore, it also surveys the opinion of Hungarian undergraduate economics students on the Hungarian economy and its sustainability. The study shows that the ability of current sustainability models and measures to give accurate portrayals of countries and regions is problematic, because they use different definitions of sustainability, use different environmental and/or economic indicators, do not differentiate between the impacts of the individual indicators, and are able to be used for political purposes. This is especially true for Hungary, as the country’s economy is crumbling with increasing social unrest, yet sustainability models give it a high ranking. Also, the Hungarian students’ views on the country’s sustainability depend on what school of economics they were taught in, and what they think about Hungary’s past, current and future economic and environmental situation.
Dan Chiras, visiting professor of environmental science and director of The Evergreen Institute in Missouri, discusses America at a crossroads in its history. The world is changing rapidly. How we react to these changes, among them global climate change and shortages of key energy resources, will determine whether we prosper or flounder. Unfortunately, extremely powerful forces now prevent us from enacting the measures required to build a truly sustainable future based on a renewable energy economy. Part of Notable Lectures & Performances series, Colorado College. Recorded April 27, 2011.