Using conservation genetics to prioritise management options for an endangered songbird.

Genetic data can be highly informative for answering questions relevant to practical conservation efforts, but remain one of the most neglected aspects of species recovery plans. Framing genetic questions with reference to practical and tractable conservation objectives can help bypass this limitation of the application of genetics in conservation. Using a single-nucleotide polymorphism dataset from reduced-representation sequencing (DArTSeq), we conducted a genetic assessment of remnant populations of the endangered forty-spotted pardalote (Pardalotus quadragintus), a songbird endemic to Tasmania, Australia. Our objectives were to inform strategies for the conservation of genetic diversity in the species and estimate effective population sizes and patterns of inter-population movement to identify management units relevant to population conservation and habitat restoration. We show population genetic structure and identify two small populations on mainland Tasmania as 'satellites' of larger Bruny Island populations connected by migration. Our data identify management units for conservation objectives relating to genetic diversity and habitat restoration. Although our results do not indicate the immediate need to genetically manage populations, the small effective population sizes we estimated for some populations indicate that they are vulnerable to genetic drift, highlighting the urgent need to implement habitat restoration to increase population size and to conduct genetic monitoring. We discuss how our genetic assessment can be used to inform management interventions for the forty-spotted pardalote and show that by assessing contemporary genetic aspects, valuable information for conservation planning and decision-making can be produced to guide actions that account for genetic diversity and increase chances of recovery in species of conservation concern.

Woodpeckers and other excavators maintain the diversity of cavity-nesting vertebrates.

Woodpeckers and other excavators create most of the holes used by secondary cavity nesters (SCNs) in North American temperate mixedwood forests, but the degree to which excavators release SCNs from nest-site limitation is debated. Our goal was to quantify how excavators maintain the diversity and abundance of secondary cavity nesters in a temperate forest through the creation of tree cavities. We examined the short- and long-term (legacy) effects of excavators (principally woodpeckers, but also red-breasted nuthatches and black-capped chickadees) on forest biodiversity using longitudinal monitoring data (1,732 nest cavities, 25 sites, 16 years) in British Columbia, Canada. Sites with higher densities of excavator nests had more cavities available, higher species richness of SCNs and higher nest density of SCNs, indicating the importance of a standing stock of cavities. Years with higher nesting densities of excavators were followed by years with higher SCN diversity, indicating that the creation of nesting opportunities through fresh excavation releases SCNs from community-wide nest-site limitation. We also show that excavators leave a 'legacy' of biodiversity (species richness and abundance) at a site by accumulating cavities at rates faster than they become unusable by decay or destruction. By quantifying site-level effects of cavity excavation on the SCN community, our study highlights the key role of excavators as ecosystem engineers that maintain forest wildlife biodiversity.

Si, dans la forêt mixte tempérée d'Amérique du Nord, les pics et autres excavateurs créent la plupart des cavités utilisées par les cavernicoles secondaires (SCN), la question de savoir s'ils augmentent la disponibilité des sites de nidification des SCN reste ouverte. Notre objectif était d'évaluer et quantifier l'impact qu'ont les excavateurs lorsqu'ils creusent des cavités dans les arbres, sur la diversité et l'abondance de cavernicoles secondaires dans une forêt mixte tempérée. Nous avons examiné les effets des excavateurs (principalement les pics, mais aussi la sittelle à poitrine rousse et la mésange à tête noire) à court et à long terme (survivance), sur la biodiversité de la forêt en Colombie-Britannique, au Canada, en utilisant des données longitudinales de surveillance (1,732 cavités ressource, 25 sites, 16 ans). Les sites à plus fortes densités de nids d'excavateurs avaient une plus grande abondance en cavités disponibles, une richesse en espèce SCN plus élevée, et une plus forte densité de nids de SCN, ce qui montre l'importance des arbres à cavités utilisables, vivants ou morts sur pied. Les années à plus fortes densités de nids d'excavateurs étaient suivies par des années à plus fortes diversités d'espèces SCN, ce qui signifie que la disponibilité de sites de nidification à partir de nouveaux creusements augmente le potentiel de nidification des espèces SCN pour l'ensemble de la communauté qui en dépend. Nous démontrons aussi que, sur un site donné, les excavateurs laissent une 'survivance' de biodiversité (richesse en espèce et abondance) en formant des cavités à un taux plus élevé que le taux avec lequel ces dernières deviennent inutilisables suite à leur décomposition ou destruction. En quantifiant les effets du creusement de cavités au niveau de chaque site par rapport à la communauté des SCN, notre étude met en évidence le rôle clé des excavateurs comme ingénieurs de l'écosystème favorisant la diversité de la faune forestière.

A trait-based framework for predicting foodborne pathogen risk from wild birds.

Recent foodborne illness outbreaks have heightened pressures on growers to deter wildlife from farms, jeopardizing conservation efforts. However, it remains unclear which species, particularly birds, pose the greatest risk to food safety. Using >11,000 pathogen tests and 1565 bird surveys covering 139 bird species from across the western United States, we examined the importance of 11 traits in mediating wild bird risk to food safety. We tested whether traits associated with pathogen exposure (e.g., habitat associations, movement, and foraging strategy) and pace-of-life (clutch size and generation length) mediated foodborne pathogen prevalence and proclivities to enter farm fields and defecate on crops. Campylobacter spp. were the most prevalent enteric pathogen (8.0%), while Salmonella and Shiga-toxin producing Escherichia coli (STEC) were rare (0.46% and 0.22% prevalence, respectively). We found that several traits related to pathogen exposure predicted pathogen prevalence. Specifically, Campylobacter and STEC-associated virulence genes were more often detected in species associated with cattle feedlots and bird feeders, respectively. Campylobacter was also more prevalent in species that consumed plants and had longer generation lengths. We found that species associated with feedlots were more likely to enter fields and defecate on crops. Our results indicated that canopy-foraging insectivores were less likely to deposit foodborne pathogens on crops, suggesting growers may be able to promote pest-eating birds and birds of conservation concern (e.g., via nest boxes) without necessarily compromising food safety. As such, promoting insectivorous birds may represent a win-win-win for bird conservation, crop production, and food safety. Collectively, our results suggest that separating crop production from livestock farming may be the best way to lower food safety risks from birds. More broadly, our trait-based framework suggests a path forward for co-managing wildlife conservation and food safety risks in farmlands by providing a strategy for holistically evaluating the food safety risks of wild animals, including under-studied species.