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...

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1. Many important insect pests undertake seasonal migrations at continental scales in response to changes in resource quality and availability. The frequency and timing of these events could be influenced by the impact of climate change on the suitability of the different sites exploited throughout the year, yet, in many cases, little is known about the origin of seasonal populations, as tracking insect movements is extremely challenging due to their small body size.2. The use of stable isotope measurements in insect tissues combined with the development of tissue-specific 'isoscapes' of modelled geographic isotope patterns presents a potentially valuable but rarely used approach for obtaining such information on important pest species. In this paper it is illustrated how stable hydrogen isotope analyses ( 2 H) in wing chitin of the true armyworm (Mythimna (Psuedaletia) unipuncta Haworth), a seasonal migrant, clearly delineated between 2016 spring immigrants and later locally produced moths in southern Ontario, Canada.3. It is shown that adult moths captured in early fall in Texas were immigrants from farther north, the first direct confirmation of a southward return migration of this species. Stable carbon isotope ( 13 C) measurements indicated that spring immigrants in Ontario and autumn immigrants in Texas were from exclusively C3 biomes. Stable nitrogen isotope ( 15 N) measurements also provided information on the probability of individuals coming from agriculturally intensive (i.e. higher 15 N) sites. Finally, several recommendations are provided regarding future research that could improve the Bayesian assignment models and thus improve assignment accuracy.

In France, illegal hunting of the endangered ortolan bunting Emberiza hortulana has been defended for the sake of tradition and gastronomy. Hunters argued that ortolan buntings trapped in southwest France originate from large and stable populations across the whole of Europe. Yet, the European Commission referred France to the Court of Justice of the European Union (EU) in December 2016 for infringements to legislation (IP/16/4213). To better assess the impact of hunting in France, we combined Pan-European data from archival light loggers, stable isotopes, and genetics to determine the migration strategy of the species across continents. Ortolan buntings migrating through France come from northern and western populations, which are small, fragmented and declining. Population viability modeling further revealed that harvesting in southwest France is far from sustainable and increases extinction risk. These results provide the sufficient scientific evidence for justifying the ban on ortolan harvesting in France.

Populations of most North American aerial insectivores have undergone steep population declines over the past 40 years but the relative importance of factors operating on breeding, wintering, or stopover sites remains unknown. We used archival light-level geolocators to track the phenology, movements and winter locations of barn swallows (Hirdundo rustica; n = 27) from populations across North America to determine their migratory connectivity. We identified an east-west continental migratory divide for barn swallows with birds from western regions (Washington State, USA (n = 8) and Saskatchewan, Canada (n = 5)) traveling shorter distances to wintering areas ranging from Oregon to northern Colombia than eastern populations (Ontario (n = 3) and New Brunswick (n = 10), Canada) which wintered in South America south of the Amazon basin. A single swallow from a stable population in Alabama shared a similar migration route to eastern barn swallows but wintered farther north in northeast Brazil indicating a potential leap frog pattern migratory among eastern birds. Six of 9 (67%) birds from the two eastern populations and Alabama underwent a loop migration west of fall migration routes including around the Gulf of Mexico travelling a mean of 2,224 km and 722 km longer on spring migration, respectively. Longer migration distances, including the requirement to cross the Caribbean Sea and Gulf of Mexico and subsequent shorter sedentary wintering periods, may exacerbate declines for populations breeding in northeastern North America.

Highlights 1. Herbivores across the mammoth steppe had broadly homogenous isotopic niches. 2. Some species shifted their niche in response to environmental conditions. 3. Overlap between species' isotopic niches suggests functional redundancy. 4. Functional redundancy made the mammoth steppe a highly resilient ecosystem. Reframing the mammoth steppe: Insights from analysis of isotopic niches.

The measurement of naturally occurring stable hydrogen (δ 2 H) and carbon (δ 13 C) isotopes in wings of the eastern North American monarch butterflies (Danaus plexippus) have proven useful to infer natal origins of individuals overwintering in Mexico. This approach has provided a breakthrough for monarch conservation because it is the only viable means of inferring origins at continental scales. Recently, routine simultaneous analyses of tissue δ 2 H and δ 18 O of organic materials has emerged leading to questions of whether the dual measurement of these isotopes could be used to more accurately infer spatial origins even though the two isotopes are expected to be coupled due to the meteoric relationship. Such refinement would potentially increase the accuracy of isotopic assignment of wintering monarchs to natal origin. We measured a sample of 150 known natal-origin monarchs from throughout their eastern range simultaneously for both δ 2 H and δ 18 O wing values. Wing δ 2 H and δ 18 O values were correlated (r 2 = 0.42). We found that wing δ 2 H values were more closely correlated with amount-weighted growing season average precipitation δ 2 H values predicted for natal sites (r 2 = 0.61) compared to the relationship between wing δ 18 O values and amount-weighted growing season average precipitation δ 18 O values (r 2 = 0.30). This suggests that monarch wing δ 2 H values will be generally more useful in natal assignments than δ 18 O values. Spatial information related to the use of deuterium excess in environmental waters was similarly found to be not useful when applied to monarch wings likely due to the considerable variance in wing δ 18 O values. Nonetheless, we recommend further testing of monarch wing δ 2 H and δ 18 O values from known natal sites with an emphasis on field data across a strong gradient in precipitation deuterium excess.

When bird populations spread, long-distance pioneering populations are often backfilled by a more slowly advancing front [1-3]. The Barn Swallow Hirundo rustica, a globally distributed passerine [4, 5], expanded its breeding range an exceptional 7,000 km when it began breeding 35 years ago in its regular wintering range in Argentina [6], subsequently expanding over 500 km from its starting point [7-11]. Trans-hemispheric breeding attempts have occurred previously in related swallows [12-14], but only this colonization has lasted. Comparative studies of birds show a remarkable diversity in patterns of change in migratory habits [15-21], and these Argentine-breeding swallows might retain ancestral patterns, breeding in Argentina but returning to North America for the austral winter. Feather isotopes from these birds are consistent with the alternative possibility that they migrate no farther than northern South America [22]. Because isotopic patterns cannot definitively distinguish these alternatives, we pursued a solar geolocator study [23, 24] to do so. Data from nine tagged birds show conclusively that Barn Swallows breeding in Argentina have rapidly changed their movements to migrate no farther north in austral winter than northern South America. The phenology of the annual cycles of molt, migration, and breeding for these Argentine-breeding swallows have all shifted by about 6 months, and we suggest that stimulatory day lengths and the proliferation of nesting substrates facilitated their colonization.