Ectoparasite Community Structure of Two Bats (Myotis lucifugus and M. septentrionalis) from the Maritimes of Canada

Prevalence of bat ectoparasites on sympatric Myotis lucifugus and M. septentrionalis was quantitatively characterized in Nova Scotia and New Brunswick by making systematic collections at swarming sites. Six species of ectoparasite were recorded, including Myodopsylla insignis, Spinturnix americanus, Cimex adjunctus, Macronyssu scrosbyi, Androlaelap scasalis, and an unknown species of the genus Acanthophthirius. Male M. lucifugus and M. septentrionalis had similar prevalence of any ectoparasite (22% and 23%, resp.). Female M. lucifugus and M. septentrionalis had 2-3 times higher prevalence than did conspecific males (68% and 44%, resp.). Prevalence of infection of both genders of young of the year was not different from one another and the highest prevalence of any ectoparasite (M. lucifugus 64%, M. septentrionalis 72%) among all bat groups. Ectoparasite prevalence and intensity varied positively with roost group size and negatively with grooming efficacy and energy budgets, suggesting that these variables may be important in ectoparasite community structure

Phenotypic plasticity and local adaptation in a wild hibernator evaluated through reciprocal translocation

Phenological shifts are the most commonly reported ecological responses to climate change and can be produced rapidly by phenotypic plasticity. However, both the limits of plasticity and whether it will be sufficient to maintain local adaptation (or even lead to maladaptation) are less clear. Increased winter precipitation has been shown to lead to phenological delays and corresponding annual decreases in fitness in Columbian ground squirrels (Urocitellus columbianus). We took advantage of natural phenological variation (across elevations) in this species to better assess the extent of phenotypic plasticity in emergence dates and the relationships between emergence dates and individual annual fitness. We coupled a reciprocal translocation experiment with natural monitoring across two populations separated by ∼500 m in elevation. Individuals in both populations responded plastically to both spring temperature and winter precipitation. Translocated individuals adjusted their emergence dates to approach those of individuals in their adoptive populations but did differ significantly in their emergence dates from residents. There were no differences in annual fitness among treatment groups nor selection on emergence date within a year. Phenotypic plasticity is thus sufficient to allow individuals to respond to broad environmental gradients, but the influence of variation in emergence dates on annual fitness requires further investigation

The energetic significance of communal roosting and insulated roost nests in a small arid-zone passerine

Small endotherms have evolved behavioural mechanisms for reducing rest-phase energy expenditure, which reduce the likelihood of mismatches between energy supply and demand during periods of cold weather and/or food scarcity. Although the energetic consequences of communal roosting and the use of insulated roosts have been the subject of numerous studies, less is known about the energy savings achieved by species that use these two behaviours simultaneously. We hypothesised that communal roosting in insulated roost nests by a small arid-zone passerine, the Scaly-feathered Finch Sporopipes squamifrons, results in additive energetic benefits that reduce nocturnal energy requirements far below those of individual birds roosting in the open. We measured metabolic rates in finches over air temperatures (Ta) between −5 and 20 °C using flow-through respirometry. Measurements were taken from single finches and groups varying in size from two to 12 individuals, with or without a roost nest. Consistent with our predictions, rest-phase resting metabolic rate (RMR) of finches decreased when the birds roosted communally and decreased further when groups were roosting in a nest. In the absence of a nest, groups of eight or 12 birds reduced RMR by >30% compared with single birds. These energy savings increased further when groups roosted in nests; at Ta = 0 °C, groups of eight or 12 finches approximately halved their RMR compared with that of groups without nests. Our data confirm that Scaly-feathered Finches save considerable energy by roosting communally in roost nests, and these behaviours likely are a key reason why this small species from subtropical latitudes can occur in areas with winter night-time temperatures as low as −10 °C.Les petites endothermes ont développé des mécanismes comportementaux pour réduire les dépenses énergétiques en phase de repos, ce qui réduit le risque de déséquilibre entre l’offre et la demande en énergie pendant les périodes de froid et / ou de pénurie alimentaire. Bien que les conséquences énergétiques des dortoirs collectifs et de l’utilisation de nids-gîtes isolés aient fait l’objet de nombreuses études, on en sait moins sur les économies d’énergie réalisées par les espèces qui utilisent simultanément ces deux comportements. Nous avons émis l’hypothèse que les dortoirs collectifs dans les nids-gîtes isolés par un petit passereau de la zone aride, le Sporopipe squameux Sporopipes squamifrons, entraîne des avantages énergétiques supplémentaires qui réduisent les besoins énergétiques nocturnes bien inférieurs à ceux des oiseaux individuels dormant à l’air libre. Nous avons mesuré les taux métaboliques chez ces tisserins à des températures de l’air (Ta) comprises entre −5 et 20 ° C en utilisant une respirométrie à flux continu. Les mesures ont été prises à partir d’oiseaux isolés et d’oiseaux groupés de taille variable allant de deux à 12 individus, avec ou sans gîte. Conformément à nos prévisions, le taux métabolique de repos (TMR) des Sporopipe au repos (phase de repos) a diminué lorsque les oiseaux se sont rassemblés en groupe et a encore diminué lorsque des groupes dormaient dans un nid. En l’absence de nid, des groupes de huit ou 12 oiseaux ont réduit le TMR de >30% par rapport aux oiseaux isolés. Ces économies d’énergie ont encore augmenté lorsque des groupes gîtent dans des nids; à Ta = 0 °C, les groupes de huit ou 12 Sporopipe ont approximativement réduit de moitié leur TMR par rapport aux groupes sans nids. Nos données confirment que les Sporopipe squameux économisent une énergie considérable en dormant ensemble dans des nids-gîtes, et que ces comportements sont probablement une des principales raisons pour lesquelles cette petite espèce de latitudes subtropicales peut être présente dans des zones où les températures nocturnes sont aussi basses que −10 °C.The DST-NRF Centre of Excellence at the FitzPatrick Institute and the University of Pretoria. This work is also based on research supported in part by the National Research Foundation of South Africa (grant number 110506).https://www.tandfonline.com/loi/tost202019-12-20hj2019Zoology and Entomolog

Extreme hyperthermia tolerance in the world’s most abundant wild bird

The thermal tolerances of vertebrates are generally restricted to body temperatures below 45–47 °C, and avian and mammalian critical thermal maxima seldom exceed 46 °C. We investigated thermoregulation at high air temperatures in the red-billed quelea (Quelea quelea), an African passerine bird that occurs in flocks sometimes numbering millions of individuals. Our data reveal this species can increase its body temperature to extremely high levels: queleas exposed to air temperature > 45 °C increased body temperature to 48.0 ± 0.7 °C without any apparent ill-effect, with individual values as high as 49.1 °C. These values exceed known avian lethal limits, with tolerance of body temperature > 48 °C unprecedented among birds and mammals.The DSI-NRF Centre of Excellence at the FitzPatrick Institute and the National Research Foundation of South Africa.http://www.nature.com/srepam2021Zoology and Entomolog

Adaptive variation in the upper limits of avian body temperature

Physiological performance declines precipitously at high body temperature (Tb), but little attention has been paid to adaptive variation in upper Tb limits among endotherms. We hypothesized that avian maximum tolerable Tb (Tbmax) has evolved in response to climate, with higher Tbmax in species exposed to high environmental heat loads or humidity-related constraints on evaporative heat dissipation. To test this hypothesis, we compared Tbmax and related variables among 53 bird species at multiple sites in South Africa with differing maximum air temperature (Tair) and humidity using a phylogenetically informed comparative framework. Birds in humid, lowland habitats had comparatively high Tbmax (mean ± SD = 45.60 ± 0.58 °C) and low normothermic Tb (Tbnorm), with a significantly greater capacity for hyperthermia (Tbmax 2 Tbnorm gradient = 5.84 ± 0.77 °C) compared with birds occupying cool montane (4.97 ± 0.99 °C) or hot arid (4.11 ± 0.84 °C) climates. Unexpectedly, Tbmax was significantly lower among desert birds (44.65 ± 0.60 °C), a surprising result in light of the functional importance of hyperthermia for water conservation. Our data reveal a macrophysiological pattern and support recent arguments that endotherms have evolved thermal generalization versus specialization analogous to the continuum among ectothermic animals. Specifically, a combination of modest hyperthermia tolerance and efficient evaporative cooling in desert birds is indicative of thermal specialization, whereas greater hyperthermia tolerance and less efficient evaporative cooling among species in humid lowland habitats suggest thermal generalization.https://www.pnas.orgdm2022Zoology and Entomolog

Thermal physiology of three sympatric small mammals from southern Africa

Please read abstract in the article.ThE National Research Foundationhttp://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-79982020-01-01hj2018Mammal Research InstituteZoology and Entomolog

How hornbills handle heat : sex-specific thermoregulation in the southern yellow-billed hornbill

At a global scale, thermal physiology is correlated with climatic variables such as temperature and aridity. There is also evidence that thermoregulatory traits vary with fine-scale microclimate, but this has received less attention in endotherms. Here, we test the hypothesis that avian thermoregulation varies with microclimate and behavioural constraints in a non-passerine bird. Male and female southern yellowbilled hornbills (Tockus leucomelas) experience markedly different microclimates while breeding, with the female sealing herself into a tree cavity and moulting all her flight feathers during the breeding attempt, becoming entirely reliant on the male for provisioning. We examined interactions between resting metabolic rate (RMR), evaporative water loss (EWL) and core body temperature (Tb) at air temperatures (Ta) between 30°C and 52°C in male and female hornbills, and quantified evaporative cooling efficiencies and heat tolerance limits. At thermoneutral Ta, neither RMR, EWL nor Tb differed between sexes. At Ta >40°C, however,RMRand EWL of females were significantly lower than those of males, by ∼13% and ∼17%, respectively, despite similar relationships between Tb and Ta, maximum ratio of evaporative heat loss to metabolic heat production and heat tolerance limits (∼50°C). These sex-specific differences in hornbill thermoregulation support the hypothesis that avian thermal physiology can vary within species in response to fine-scalemicroclimatic factors. In addition,Q10 for RMR varied substantially, with Q10 ≤2 in some individuals, supporting recent arguments that active metabolic suppression may be an underappreciated aspect of endotherm thermoregulation in the heat.The National Research Foundation SARChI chair for Mammal Behavioural Ecology and Physiology, the SARChI chair of Conservation Physiology, the Centre of Excellence at the FitzPatrick Institute of African Ornithology and the Claude Leon Foundation.http://jeb.biologists.orgam2022Mammal Research InstituteZoology and Entomolog

Dactylanthus flower visitation by New Zealand lesser short-tailed bats appears to be influenced by daily rainfall

The unique relationship between Dactylanthus taylorii and its pollinator, the New Zealand lesser short-tailed bat (Mystacina tuberculata), is poorly understood despite both species being threatened. We used data collected over two summers (2016 and 2017) to determine if mean ambient temperature and total daily rainfall during the flowering period affected flower visitation by bats. We placed dataloggers around D. taylorii inflorescences to monitor bats with implanted passive integrated transponders (PIT-tags). We determined that flower visitation and bat activity was negatively correlated with daily rainfall but not temperature. Further, we found that juveniles and adult males were much more common visitors, with only four visits from adult females in two years. There is still much to learn about the unique and vulnerable relationship between these two New Zealand species, but it appears that rainfall may play a larger role than previously though

Weather and demographics affect Dactylanthus flower visitation by New Zealand lesser short-tailed bats

Dactylanthus taylorii is thought to be the only ground-flowering plant to be pollinated by a bat" the New Zealand lesser short-tailed bat (Mystacina tuberculata). This unique mutualistic relationship is poorly understood despite both species being threatened. We placed dataloggers around distinct clumps of D. taylorii inflorescences to monitor bats with implanted passive integrated transponders (PIT-tags) and quantify visitation rates and demography during the late-summer flowering season. Adult males and juveniles visited flowers more frequently than adult females. Adult males may have visited flowers to feed on nectar and offset the energy demands of advertising, lek defence and mating, and/or reduced foraging time during summer. Juvenile bats may be under increased energetic burdens due to naïve foraging behaviour and use nectar to augment low energy reserves. The frequency of visits correlated positively with mean night ambient temperature, likely because of increased prey, and therefore, bat activity. Our study is the first to examine the demographics of M. tuberculata visiting D. taylorii and serves as a baseline for future studies considering these unique and vulnerable New Zealand species

Hot bats go cold: heterothermy in neotropical bats

Torpor is common in bats, but has historically been viewed as an energy-saving technique reserved for temperate and subarctic climates" however, torpor use is common across several tropical bat families. Central America hosts a great diversity of bats with approximately 150 species, yet data from this area are lacking compared with tropical Africa and Australia. We investigated thermoregulatory responses of bats from neotropical Belize and captured adult bats in the tropical forests of Lamanai Archeological Reserve, Belize. After a 12 h acclimation period, we recorded rectal temperature prior to and after exposing bats to an ambient temperature (Ta) of 7 °C for up to 2 h in an environmental chamber. All 11 species across four families expressed torpor to some degree upon exposure to cool temperatures. Individuals from Vespertilionidae defended the lowest resting body temperature (Tb) and showed the greatest decrease in Tb after acute exposure to low Ta. Our data help to establish a new spectrum of physiological ability for this group of mammals and shed light on the evolution of torpor and heterothermy. We show that energy conservation is important even in warm and energetically stable environmental conditions. Understanding how and why torpor is used in warm climates will help to better define paradigms in physiological ecology