Modeling and Mapping Golden-winged Warbler Abundance to Improve Regional Conservation Strategies

Conservation planning requires identifying pertinent habitat factors and locating geographic locations where land management may improve habitat conditions for high priority species. I derived habitat models and mapped predicted abundance for the Golden-winged Warbler (Vermivora chrysoptera), a species of high conservation concern, using bird counts, environmental variables, and hierarchical models applied at multiple spatial scales. My aim was to understand habitat associations at multiple spatial scales and create a predictive abundance map for purposes of conservation planning for the Golden-winged Warbler. My models indicated a substantial influence of landscape conditions, including strong positive associations with total forest composition within the landscape. However, many of the associations I observed were counter to reported associations at finer spatial extents; for instance, I found Golden-winged Warblers negatively associated with several measures of edge habitat. No single spatial scale dominated, indicating that this species is responding to factors at multiple spatial scales. I found Golden-winged Warbler abundance was negatively related with Blue-winged Warbler (Vermivora cyanoptera) abundance. I also observed a north-south spatial trend suggestive of a regional climate effect that was not previously noted for this species. The map of predicted abundance indicated a large area of concentrated abundance in west-central Wisconsin, with smaller areas of high abundance along the northern periphery of the Prairie Hardwood Transition. This map of predicted abundance compared favorably with independent evaluation data sets and can thus be used to inform regional planning efforts devoted to conserving this species.

Flight initiation distances of nesting Piping Plovers (Charadrius melodus) in response to human disturbance

Birds frequently interact with people when they occur in coupled human-ecological or anthropogenic environments, which makes the protection of legally protected species a challenge. Flight initiation distances (FIDs) are often used to inform development of appropriate buffer distances required for human exclusion zones used to protect birds nesting in anthropogenic landscapes. Piping Plovers (Charadrius melodus) are protected by the Endangered Species Act in the United States and often nest in areas used by humans. Studies evaluating Piping Plover FIDs are limited and implementation of exclusion zones has been inconsistent across the species’ range. We measured Piping Plover response and FIDs to naturally occurring stimuli on public beaches at Lake McConaughy, Nebraska, USA. Piping Plover FIDs differed most by stimulus class (vehicle, human, dog, human with dog), Julian day, and hour of day. Piping Plover FIDs were greatest for dog and human with dog compared to humans and vehicles. For all types of stimuli, Piping Plover FIDs decreased over time during the nesting season and increased slightly during each day. In the majority of instances in which Piping Plovers left their nests, return times to the nest were relatively short (less than three minutes). These results suggest Piping Plovers become habituated to the presence of human-related stimuli over the course of a nesting season, but other explanations such as parental investment and risk allocation cannot be excluded. Additional research and improved guidance regarding the implementation of exclusion zones is needed so managers can implement effective protection programs in anthropogenic landscapes.

Biased representation of disturbance rates in the roadside sampling frame in boreal forests: implications for monitoring design

The North American Breeding Bird Survey (BBS) is the principal source of data to inform researchers about the status of and trend for boreal forest birds. Unfortunately, little BBS coverage is available in the boreal forest, where increasing concern over the status of species breeding there has increased interest in northward expansion of the BBS. However, high disturbance rates in the boreal forest may complicate roadside monitoring. If the roadside sampling frame does not capture variation in disturbance rates because of either road placement or the use of roads for resource extraction, biased trend estimates might result. In this study, we examined roadside bias in the proportional representation of habitat disturbance via spatial data on forest “loss,” forest fires, and anthropogenic disturbance. In each of 455 BBS routes, the area disturbed within multiple buffers away from the road was calculated and compared against the area disturbed in degree blocks and BBS strata. We found a nonlinear relationship between bias and distance from the road, suggesting forest loss and forest fires were underrepresented below 75 and 100 m, respectively. In contrast, anthropogenic disturbance was overrepresented at distances below 500 m and underrepresented thereafter. After accounting for distance from road, BBS routes were reasonably representative of the degree blocks they were within, with only a few strata showing biased representation. In general, anthropogenic disturbance is overrepresented in southern strata, and forest fires are underrepresented in almost all strata. Similar biases exist when comparing the entire road network and the subset sampled by BBS routes against the amount of disturbance within BBS strata; however, the magnitude of biases differed. Based on our results, we recommend that spatial stratification and rotating panel designs be used to spread limited BBS and off-road sampling effort in an unbiased fashion and that new BBS routes be established where sufficient road coverage exists.