GABB : A global dataset of alpine breeding birds and their ecological traits

Alpine ecosystems represent varied climates and vegetation structures globally, with the potential to support rich and functionally diverse avian communities. High mountain habitats and species are under significant threat from climate change and other anthropogenic factors. Yet, no global database of alpine birds exists, with most mountain systems lacking basic information on species breeding in alpine habitats, their status and trends, or potential cryptic diversity (i.e., sub-species distributions). To address these critical knowledge gaps, we combined published literature, regional monitoring schemes, and expert knowledge from often inaccessible, data-deficient mountain ranges to develop a global list of alpine breeding bird species with their associated distributions and select ecological traits. This dataset compiles alpine breeding records for 1,310 birds, representing 12.0% of extant species and covering all major mountain regions across each continent, excluding Antarctica. The Global Alpine Breeding Bird dataset (GABB) is an essential resource for research on the ecological and evolutionary factors shaping alpine communities, as well as documenting the value of these high elevation, climate-sensitive habitats for conserving biodiversity.Peer reviewe

Observed instances of alarm calling in the Cape Rockjumper

Here I give an account of alarm calls recorded during behavioural observations on Cape Rockjumpers (CRJs) and the potential predators observed nearby. I found CRJs did not produce alarm calls in the presence of Boomslang (a previously known predator of CRJ nestlings), whereas they did produce alarm calls in the presence of Rock Kestrels, which was unexpected as previous literature suggested Rock Kestrels do not prey upon CRJ. However, during field observations I witnessed a Rock Kestrel attack an adult CRJ, suggesting that Rock Kestrels may opportunistically prey upon CRJs. Further studies on site- and temporal-specificity in CRJs may lead to additional understanding of the flexibility of alarm calling in group-living species.Keywords: alarm calling, Cape Rockjumper, sentinel behaviou

Population Viability Analysis for a vulnerable ground-nesting species, the Cape Rockjumper Chaetops frenatus: assessing juvenile mortality as a potential area for conservation management

As an endemic bird to the Fynbos biome, prominently featured in literature and marketing material for the avifauna of the continent, the Cape Rockjumper Chaetops frenatus is an iconic species of South Africa. Building on studies from the past decade, recent publications all point to a vulnerability to climate change due to temperature-related effects on their behaviour, physiology, and life history. Here we present a population viability analysis for the species based on knowledge of recent declines and making use of recently available information on their life history. We combined recent breeding success data (2016–2018) with that of a population monitored approximately two decades ago (1998–2000) and modelled the probability of extinction for four scenarios where the principal change was in juvenile (more accurately, nestling) mortality. We focused on juvenile mortality as there are previously identified areas of vulnerability that present potential areas for mitigation. With juvenile mortality set at the recently recorded rate of 80% there is a 49.1% chance of population extinction within 100 years, despite optimistic adult survival and breeding parameters used in the models. We then provide insights into factors that mediate juvenile mortality as potential avenues for the management of the species. Analyse de la viabilité de la population d’une espèce vulnérable nichant au sol, le Rockjumper du Cap Chaetops frenatus : évaluation de la mortalité juvénile comme domaine potentiel de gestion de la conservation. En tant qu’oiseau endémique du biome du Fynbos, figurant en bonne place dans la littérature et le matériel de marketing sur l’avifaune du continent, le Rockjumper du Cap Chaetops frenatus est une espèce emblématique de l’Afrique du Sud. S’appuyant sur les études de la dernière décennie, les publications récentes indiquent toutes une vulnérabilité au changement climatique en raison des effets liés à la température sur leur comportement, leur physiologie et leur cycle de vie. Nous présentons ici une analyse de la viabilité de la population de l’espèce basée sur la connaissance des déclins récents et utilisant les informations récemment disponibles sur leur histoire de vie. Nous avons combiné des données récentes sur le succès de la reproduction (2016–2018) avec celles d’une population suivie il y a environ deux décennies (1998–2000) et nous avons modélisé la probabilité d’extinction pour quatre scénarios où le principal changement était la mortalité des juvéniles (plus précisément, des oisillons). Nous nous sommes concentrés sur la mortalité juvénile car il existe des zones de vulnérabilité identifiées précédemment qui présentent des zones potentielles d’atténuation. Si la mortalité juvénile est fixée au taux de 80% récemment enregistré, le risque d›extinction de la population dans les 100 ans est de 49.1%, malgré les paramètres optimistes de survie et de reproduction des adultes utilisés dans les modèles. Nous fournissons ensuite des informations sur les facteurs qui interviennent dans la mortalité juvénile comme pistes potentielles pour la gestion de l’espèce

Comparison of physiological responses to high temperatures in juvenile and adult Cape Rockjumpers Chaetops frenatus

Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.Keywords: avian physiology, climate change, climate relict, juvenile physiology, South Africa endemi

Increasing temperatures increase the risk of reproductive failure in a near threatened alpine groundnesting bird, the Cape Rockjumper Chaetops frenatus:

A major cause of reproductive failure in birds is nest predation. Predation risk depends on predator type, as predators vary in their ecology and sensory modalities (e.g. visual vs. olfactory). Snakes (generally olfactory predators) are a major nest predator for small birds, with predation strongly associated with higher temperatures. We investigated nest survival in a ground‐nesting alpine species, the Cape Rockjumper Chaetops frenatus , endemic to alpine fynbos in southwestern South Africa. We collected 3 years of nest data, testing whether nest survival was related to (1) habitat stage (early post‐fire vs. late post‐fire habitat, ≤ 3 and > 3 years since fire respectively), (2) nest concealment and (3) temperature. We found that nests had better survival at lower temperatures, with snake predation (our main source of predation) increasing in higher temperatures