Acoustic recordings are increasingly used to quantify occupancy and abundance in avian monitoring and research. The recent development of relatively inexpensive programmable autonomous recording units (ARUs) has further increased the utility of acoustic recording technologies. Despite their potential advantages, persistent questions remain as to how comparable data are between ARUs and traditional (human observer) point counts. We suggest that differences in counts obtained from ARUs versus human observers primarily stem from differences in the effective detection radius of humans (EDR H ) versus ARUs (EDR A ). We describe how paired sampling can be used in conjunction with generalized linear (GLM) or generalized linear mixed models (GLMM) to estimate correction factors (δ) to remove biases between ARUs and traditional point counts. Furthermore, if human observers conduct distance estimation, we show that density estimates can be derived from single ARUs by estimating EDR A as a function of EDR H and δ, thus providing alternatives to more complicated and expensive approaches. We demonstrate our approach using data from 363 point count stations in 105 unique boreal study sites at which field staff conducted point count surveys that were simultaneously recorded by an ARU and later transcribed in the lab. Finally, we used repeated random subsampling of the data to split the data into model creation (70%) and validation (30%) subsets to iteratively estimate δ and validate density estimates from ARUs against densities calculated from human observers at the same independent validation locations. We modeled density of 35 species of boreal forest birds and show that incorporating δ in statistical offsets successfully removes systematic biases in estimated avian counts and/or density between human and ARU derived surveys. Our method is therefore easily implemented and will facilitate the integration of ARU and human observer point count data, facilitating expanded monitoring efforts and meta-analyses with historic point count data. Standardisation de données de points d'écoute issus d'échantillons appariés d'observateurs et d'enregistrements acoustiquesRÉSUMÉ. Les enregistrements acoustiques sont de plus en plus utilisés pour quantifier l'occurrence et l'abondance dans le cadre de suivis et de recherches aviaires. Le développement récent d'unités d'enregistrement autonomes (ARU, pour autonomus recording units), programmables et plutôt bon marché a contribué à hausser l'utilité des technologies d'enregistrement acoustique. En dépit de leurs avantages possibles, des questions demeurent quant à la comparabilité des données issues de points d'écoute traditionnels (observateur humain) et d'ARU. Nous supposons que les différences obtenues entre les dénombrements issus d'ARU et ceux issus d'observateurs proviennent de différences dans le rayon de détection effectif (EDR, pour effective dectection radius) des humains (EDRH) comparativement à celui des ARU (EDRA). Nous décrivons de quelle façon un échantillonnage apparié peut être...

Enrichment is widely used as tool for managing fearfulness, undesirable behaviors, and stress in captive animals, and for studying exploration and personality. Inconsistencies in previous studies of physiological and behavioral responses to enrichment led us to hypothesize that enrichment and its removal are stressful environmental changes to which the hormone corticosterone and fearfulness, activity, and exploration behaviors ought to be sensitive. We conducted two experiments with a captive population of wild-caught Clark's nutcrackers (Nucifraga columbiana) to assess responses to short- (10-d) and long-term (3-mo) enrichment, their removal, and the influence of novelty, within the same animal. Variation in an integrated measure of corticosterone from feathers, combined with video recordings of behaviors, suggests that how individuals perceive enrichment and its removal depends on the duration of exposure. Short- and long-term enrichment elicited different physiological responses, with the former acting as a stressor and birds exhibiting acclimation to the latter. Non-novel enrichment evoked the strongest corticosterone responses of all the treatments, suggesting that the second exposure to the same objects acted as a physiological cue, and that acclimation was overridden by negative past experience. Birds showed weak behavioral responses that were not related to corticosterone. By demonstrating that an integrated measure of glucocorticoid physiology varies significantly with changes to enrichment in the absence of agonistic interactions, our study sheds light on potential mechanisms driving physiological and behavioral responses to environmental change.

Autonomous recording units (ARUs) are emerging as a useful technology for the study and monitoring of animals that produce vocalizations. During summer and fall of 2013, we performed a series of experiments aimed at developing sampling protocols to count nocturnally active yellow rails (Coturnicops noveboracensis) from sound recordings. Field-based portions of the work took place in the rural municipality of Foam Lake, Saskatchewan, Canada, in an open landscape where yellow rails can be found during the breeding season; lab-based portions of the work occurred in Saskatoon, Saskatchewan, Canada. Our objectives were to 1) determine the frequency of yellow rail vocalizations to derive an empirically based sampling interval for counting individual birds; 2) assess the accuracy of yellow rail counts made from recordings; 3) determine the approximate sampling radius of the ARU for detecting yellow rails; and 4) determine the approximate audio volume ("loudness") of yellow rail calls. We developed a sonogram-based method for counting individual birds on recordings. Using field recordings of individual yellow rails, we generated recordings with known numbers of calling individuals (i.e., 1-12) and tested the accuracy of the sonogram-based counts. Regardless of experience, observers were able to determine the number of rails calling with a high level of accuracy, especially when the chorus was composed of 6 individuals. From broadcast trials employing multiple ARUs, we found the effective detection radius of calling yellow rails to be between 150 m and 175 m. Although detection radius was influenced by broadcast intensity and ambient conditions, we view this range of distance as a reasonable estimate of the effective sampling radius for the ARUs that we used, which is useful for deriving values of density estimates. Finally, we measured loudness of yellow rail calling at approximately 95 dB; this value is useful to research efforts attempting to mimic actual yellow rails (e.g., call-broadcast surveys, additional ARU experiments). A combination of the sonogramcounting method and baseline information on detection radius of the ARU provides a tool that will generate high-quality data on yellow rail occurrence, abundance, and density. Digital recorders represent a means to rapidly improve survey coverage of yellow rails throughout the species' range. Ó 2016 The Wildlife Society.

Enrichment is widely used as tool for managing fearfulness, undesirable behaviors, and stress in captive animals, and for studying exploration and personality. Inconsistencies in previous studies of physiological and behavioral responses to enrichment led us to hypothesize that enrichment and its removal are stressful environmental changes to which the hormone corticosterone and fearfulness, activity, and exploration behaviors ought to be sensitive. We conducted two experiments with a captive population of wild-caught Clark's nutcrackers (Nucifraga columbiana) to assess responses to short-(10-d) and long-term (3-mo) enrichment, their removal, and the influence of novelty, within the same animal.Variation in an integrated measure of corticosterone from feathers, combined with video recordings of behaviors, suggests that how individuals perceive enrichment and its removal depends on the duration of exposure. Short-and long-term enrichment elicited different physiological responses, with the former acting as a stressor and birds exhibiting acclimation to the latter. Non-novel enrichment evoked the strongest corticosterone responses of all the treatments, suggesting that the second exposure to the same objects acted as a physiological cue, and that acclimation was overridden by negative past experience. Birds showed weak behavioral responses that were not related to corticosterone. By demonstrating that an integrated measure of glucocorticoid physiology varies significantly with changes to enrichment in the absence of agonistic interactions, our study sheds light on potential mechanisms driving physiological and behavioral responses to environmental change.

Climate change is expected to increase the extent and severity of wildfires throughout the boreal forest. Historically, black spruce (Picea mariana (Mill.) B.S.P.) forests in interior Alaska have been relatively free of non-native species, but the compounding effects of climate change and an altered fire regime could facilitate the expansion of non-native plants. We tested the effects of wildfire on non-native plant colonization by conducting a seeding experiment of non-native plants on different substrate types in a burned black spruce forest, and surveying for non-native plants in recently burned and mature black spruce forests. We found few non-native plants in burned or mature forests, despite their high roadside presence, although invasion of some burned sites by dandelion (Taraxacum officinale) indicated the potential for non-native plants to move into burned forest. Experimental germination rates were significantly higher on mineral soil compared to organic soil, indicating that severe fires that combust much of the organic layer could increase the potential for non-native plant colonization. We conclude that fire disturbances that remove the organic layer could facilitate the invasion of non-native plants providing there is a viable seed source and dispersal vector.