Avian use of anthropogenic and natural habitats in a small island developing state

Avian species on Small Island Developing States (SIDS) are at particular risk from agricultural and urban expansion and climate change. However, creating appropriate management and mitigation actions for SIDS is challenging because ecological and conservation data are often unavailable. To better understand natural and anthropogenic habitat use by resident bird species in a small Neotropical SIDS, we conducted a systematic, community-wide survey of the distribution, diversity, and abundance of Grenada's land birds. Higher densities of most species were found in anthropogenic cultivated and secondary grasslands, while cloud and secondary forests had lower densities of most species. Nonetheless, cloud and secondary forests were selected by some species of conservation concern, such as the regionally endemic Lesser Antillean Tanager (Tangara cucullata), Grenada Flycatcher (Myiarchus nugator), and all nectarivores. Nectarivores tended to avoid urban habitats. Our results suggest that many avian species in Grenada make significant use of low-intensity agricultural and rural landscapes, and such habitats should be considered in the conservation of avian communities. Conservation of resident land- bird communities across this region will require maintaining a habitat mosaic of natural and anthropogenic habitat types, and collaboration among a wide range of government and non-governmental stakeholders

Song adjustments only partially restore effective communication among Baird's sparrows, Centronyx bairdii, exposed to oil well drilling noise

Noise from oil and gas development is pervasive across many landscapes and creates a novel soundscape that wildlife must adapt to or avoid. In response to anthropogenic noise, many wildlife species alter their vocalizations. Some adjusted vocalizations may promote effective communication in the presence of noise by improving detection and preserving information about the sender's status. However, if adjusted vocalizations fail to improve communication in noise, both missed detections and misinterpretations of vocalizations could impact the fitness of individuals and ultimately contribute to population declines. Baird's sparrow is a species at risk in Canada that adjusts its songs in response to oil well drilling noise by altering whole-song elements such as decreasing the peak frequency of songs (Curry et al., 2017, Bioacoustics, 27(2), 105–130). We examined the efficacy of these adjusted songs in the mixed-grass prairies of southern Alberta, Canada during the Baird's sparrow breeding season (May–July 2018 and 2019) using a repeated measures study design (N = 69 dyads) in which we simulated territorial intrusions by broadcasting adjusted songs and unadjusted songs in the presence and absence of oil well drilling noise recordings. We found that focal male behaviour was mainly mediated by noise treatment when compared to song treatment. In noisy trials, males sang less, called more and performed more flybys, regardless of song treatment type. However, in noisy trials, males displayed longer song latency in response to unadjusted songs compared to adjusted songs. The results of our novel study suggest that the presence of oil well drilling noise elicits more aggressive territorial defence behaviour in Baird's sparrows or hinders the ability of individuals to locate or assess rivals. Additionally, our results suggest that adjusted songs only partially restore effective communication in noise

Lovers, not fighters : docility influences reproductive fitness, but not survival, in male Cape ground squirrels, Xerus inauris

Over their lifetime, individuals may use different behavioural strategies to maximize their fitness. Some behavioural traits may be consistent among individuals over time (i.e., ‘personality’ traits) resulting in an individual behavioural phenotype with different associated costs and benefits. Understanding how behavioural traits are linked to lifetime fitness requires tracking individuals over their lifetime. Here, we leverage a long-term study on a multi-year living species (maximum lifespan ~ 10 years) to examine how docility (an individual’s reaction to trapping and handling) may contribute to how males are able to maximize their lifetime fitness. Cape ground squirrels are burrowing mammals that live in social groups, and although males lack physical aggression and territoriality, they vary in docility. Males face high predation risk and high reproductive competition and employ either of two reproductive tactics (‘natal’ or ‘band’) which are not associated with different docility personalities. We found that although more docile individuals sired more offspring on an annual basis, docility did not affect an individual’s long-term (lifetime) reproductive output. Survival was not associated with docility or body condition, but annual survival was influenced by rainfall. Our findings suggest that although docility may represent a behavioural strategy to maximize fitness by possibly playing a role in female-male associations or female mate-choice, variations in docility within our study population is likely maintained by other environmental drivers. However, individual variations in behaviours may still contribute as part of the ‘tool kit’ individuals use to maximize their lifetime fitness

Lovers, not fighters: docility influences reproductive fitness, but not survival, in male Cape ground squirrels, Xerus inauris

DATA AVAILABILITY : All data analyzed for this study are included in this published article and its supplementary information files.Over their lifetime, individuals may use different behavioural strategies to maximize their fitness. Some behavioural traits may be consistent among individuals over time (i.e., ‘personality’ traits) resulting in an individual behavioural phenotype with different associated costs and benefits. Understanding how behavioural traits are linked to lifetime fitness requires tracking individuals over their lifetime. Here, we leverage a long-term study on a multi-year living species (maximum lifespan ~ 10 years) to examine how docility (an individual’s reaction to trapping and handling) may contribute to how males are able to maximize their lifetime fitness. Cape ground squirrels are burrowing mammals that live in social groups, and although males lack physical aggression and territoriality, they vary in docility. Males face high predation risk and high reproductive competition and employ either of two reproductive tactics (‘natal’ or ‘band’) which are not associated with different docility personalities. We found that although more docile individuals sired more offspring on an annual basis, docility did not affect an individual’s long-term (lifetime) reproductive output. Survival was not associated with docility or body condition, but annual survival was influenced by rainfall. Our findings suggest that although docility may represent a behavioural strategy to maximize fitness by possibly playing a role in female-male associations or female mate-choice, variations in docility within our study population is likely maintained by other environmental drivers. However, individual variations in behaviours may still contribute as part of the ‘tool kit’ individuals use to maximize their lifetime fitness.The Natural Sciences and Engineering Research Council of Canada Discovery Grant, NSERC Small Research Equipment Grant, Canadian Foundation for Innovation and the Manitoba Research and Innovation Grant, University of Manitoba Faculty of Science Field Work Support Program funding, the University of Manitoba Research Grants Program, the Faculty of Science and an Oxford Brookes Emerging Leaders Research Fellowship.http://link.springer.com/journal/265hj2024Mammal Research InstituteZoology and EntomologyNon

Temperature-associated morphological changes in an African arid-zone ground squirrel

The ecology, life histories, and physiology of many animals are changing in response to human-induced climate change. As the Earth warms, the ability of an animal to thermoregulate becomes ecologically and physiologically significant. Morphological adaptations to warmer temperatures include larger appendages and smaller bodies. We examined morphological features in a ground squirrel, Xerus inauris, living in the arid zones of South Africa, to examine whether squirrels have responded to increases in temperature and changes in seasonal rainfall with morphological modifications over the last 18 years. We found that over time, absolute hindfoot length and proportional hindfoot length increased, while spine length decreased. These changes are consistent with ecogeographical rules (Allen’s rule and Bergmann’s rule) and provide evidence in support of “shape-shifting” in response to climatic warming. Body mass also increased with time; however, these changes were not consistent with Bergmann’s rule, indicating that mass is influenced by other ecological factors (e.g., resource availability). Our study adds to the growing evidence that animal morphologies are changing in response to changing climatic conditions, although it remains to be seen whether these changes are adaptive.https://academic.oup.com/jmammal2023-11-23Mammal Research InstituteZoology and Entomolog

Within-group vocal differentiation of individuals in the cooperatively breeding apostlebird

The ability of animals to discriminate between individuals or groups of individuals (e.g., kin or nonkin) is an important component of many hypotheses proposed to explain the evolution of cooperation and benefits of group living. Previous studies in mammalian systems have demonstrated the use of vocal cues in individual recognition and discrimination. However, there are few such studies in birds. Previous avian studies have largely examined discrimination between different categories of individuals (e.g., mate vs. nonmate, offspring vs. non-offspring) while discrimination between individuals of the same category remain largely unexplored. Previous work has demonstrated that the contact calls of free-living apostlebirds ('Struthidea cinerea') are individually distinct. Here, we demonstrate that apostlebirds can differentiate between the calls of other individuals of the same social group using vocal cues alone. These findings are biologically relevant as apostlebirds live in complex fission-fusion societies where social groups vary in size, sex ratio, number of breeders, and composition of related and unrelated members

Within-group vocal differentiation of individuals in the cooperatively breeding apostlebird

The ability of animals to discriminate between individuals or groups of individuals (e.g., kin or nonkin) is an important component of many hypotheses proposed to explain the evolution of cooperation and benefits of group living. Previous studies in mammalian systems have demonstrated the use of vocal cues in individual recognition and discrimination. However, there are few such studies in birds. Previous avian studies have largely examined discrimination between different categories of individuals (e.g., mate vs. nonmate, offspring vs. non-offspring) while discrimination between individuals of the same category remain largely unexplored. Previous work has demonstrated that the contact calls of free-living apostlebirds (Struthidea cinerea) are individually distinct. Here, we demonstrate that apostlebirds can differentiate between the calls of other individuals of the same social group using vocal cues alone. These findings are biologically relevant as apostlebirds live in complex fission–fusion societies where social groups vary in size, sex ratio, number of breeders, and composition of related and unrelated members.9 page(s

Effects of noise from four types of extractive energy infrastructure on song features in Savannah Sparrows (Passerculus sandwichensis)

Human activities change the acoustic environment in many setting around the world. These changes are complex, as different anthropogenic sound sources create different acoustic profiles; therefore, some sound sources may have greater impacts on wildlife than others. Animals may adapt to these altered acoustic environments by adjusting their vocalizations. In the case of bird song, this may be achieved by adjusting the whole song, which may preserve the spectral and temporal relationships between successive syllables, or adjusting components (syllables) within the song. Determining which syllables are adjusted may help elucidate the mechanisms, benefits, and limitations to song plasticity. We examined effects of conventional industrial infrastructure used to extract shallow natural gas and petroleum (natural gas compressor stations, generator-powered oil well pumpjacks, power grid-powered oil well screw pumps, and generator-powered oil well screw pumps), compared with quiet control sites, on 15 variables describing the acoustic properties of whole songs and syllables in Savannah Sparrows (Passerculus sandwichensis). Changes in acoustic properties varied with syllable and infrastructure type: most effects occurred at generator-powered screw pump sites, the loudest type of infrastructure that we studied. We found no effects of infrastructure on whole song variables, but song minimum frequency increased with ambient background noise. We found differing effects of infrastructure types on individual syllable types, with alterations in frequencies, tonality and syllable duration. This suggests that some syllables may be more plastic in their response than others, which may allow Savannah Sparrows to adapt their communication in altered acoustic environments