Biology subjects

Burness, G.

Publications and source records attributed to Burness, G..

15 recordsLinked to original sources

bioRxiv2026

Artificial light at night and concealment level affect detection probability of stranded seabirds: a study with 3D-printed puffin decoys

Fledglings of burrow-nesting seabirds are vulnerable to disorientation by artificial light at night (ALAN) and grounding in coastal human settlements, where most individuals presumably perish if not rescued. Accurate estimates of the effects of stranding on seabird populations remain elusive due to several levels of uncertainty, such as the number of stranded seabirds estimated to remain undiscovered by rescuers. One species subjected to stranding is the Atlantic puffin (Fratercula arctica). We hypothesized that the detection probability of puffin fledglings by the Puffin Patrol rescue program, operating in Newfoundland, Canada, is affected by light level, concealment level, and search effort. We deployed realistic puffin decoys in locations of varying light and concealment levels throughout two sites that are searched nightly by rescuers and measured the amount of time and search effort required until each decoy was found. Approximately 78% more search effort was required to find a decoy in darkness (32.0 min) compared with illuminated conditions (18.0 min), and up to 100% more search effort was required to find a decoy placed in concealed conditions (35.5 min) than one in the open (17.5 min). After two hours of searching, on average over 10% of decoys were still not found, although each additional minute of search effort increased detection rate of an individual decoy by 0.6%. In combination with recent advances in our knowledge of seabird post-stranding behaviour, our study offers a first step in the development of correction factors which can be adapted to site- and species-specific requirements of other rescue programs around the world that rely on volunteers to search for stranded birds. Application of such correction factors will hopefully result in better estimation of mortality rates and their resultant effects on populations.

zoology↗

bioRxiv2025

Effects of partner workload and increasing environmental temperature on nestling provisioning and body temperature in a declining aerial insectivore

Research HighlightsIn adult male tree swallows, we found that experimental manipulations of heat dissipation capacity had little effect on the provisioning rate, body temperature, nor growth of nestlings. That males did not respond to enhanced heat dissipation suggests that they may provision below the threshold of overheating. Rather, male provisioning was affected by the provisioning rate of the males partner and environmental temperature. With climate change, birds will face increasing thermoregulatory demands, which may alter reproductive behaviors such as offspring provisioning. Experimental studies have shown that the provisioning capacity of female tree swallows (Tachycineta bicolor) is limited by their risk of overheating. Given that parental investment strategies may vary between sexes, the thermal environment may have a different impact on males. We experimentally trimmed ventral feathers from male tree swallows to create a "thermal window" through which they could dissipate heat. We remotely monitored provisioning rate and core body temperature of males and their female partners. At high temperatures, all males decreased their nestling provisioning rates irrespective of trimming treatment. In addition, trimmed males maintained core body temperatures similar to those of controls. This suggests that in contrast to previous work with females, males limit provisioning rates to levels below the threshold at which they would overheat. Regardless of male treatment, females adjusted their own activity to match that of their male partners; whether there are costs to females is unknown. Combined, these studies highlight that sex-specific differences in thermal physiology and behavior must be considered when predicting responses to climatic warming.

animal behavior and cognition↗

bioRxiv2024

Under Cover of Darkness: Refuge from Artificial Light at Night may Mitigate Risks to Stranded Seabirds

Artificial light at night is an anthropogenic pollutant that has wide-ranging effects on wildlife. Fledgling seabirds of the order Procellariiformes exhibit phototaxis toward artificial lights on their first flights from the nest, causing them to become grounded in human settlements where they are subject to increased risk of predation. Limited evidence suggests that certain light types may be less attractive than others, yet there is also evidence for an aversion to light under certain circumstances. We investigated differences in phototactic behaviour, activity level, and shelter-seeking behaviour of grounded Hydrobates leucorhous (Leachs storm-petrel) fledglings exposed to artificial light in three experiments: a Y-maze choice experiment, an open field test, and a modified open field test with a hide box provided ("Safe Haven test"). When provided with combinations of different light types in the Y-maze, storm-petrels typically remained stationary in the darkest part of the apparatus and exhibited no response toward one light type over another. This was consistent with results from the open field test, in which individuals were less active in darkness than when exposed to two out of three light conditions (Warm White Light-Emitting Diode and High Pressure Sodium). More than half of birds entered the hide box in light conditions, compared to none in the dark. Considered together, our results indicate Leachs storm-petrel fledglings exhibit photophobic behaviour after stranding, which may be part of a behavioural strategy to avoid predation. Further, we demonstrate the utility of providing hide boxes to protect stranded seabird fledglings in locations where lighting cannot be eliminated or where rescue efforts may be limited in spatial or temporal coverage. However, hide boxes would have limited utility in dark locations. Hide boxes constitute a novel mitigation measure that merits future testing for its ability to reduce stranding-induced mortality, especially in imperiled procellariiform species. LAY SUMMARYO_LIGlobally, fledglings of many seabird species become stranded in towns and at industrial sites near their breeding colonies C_LIO_LIStrandings are thought to be caused by attraction to lights, although some species appear to avoid light C_LIO_LIWe tested behavioural responses and activity levels of Leachs storm-petrel fledglings toward several different light types C_LIO_LIWhen presented with different types of light in a choice experiment, most birds remained stationary C_LIO_LIFledglings were more active in warm-hued lights than in darkness C_LIO_LIBirds sought shelter when it was provided in light conditions, but not when provided in darkness C_LIO_LIOur results suggest that rescue programs targeting Leachs storm-petrels should include searches in dark, hidden locations where fledglings are likely to hide, and support the use of small shelters to protect stranded seabirds when lights cannot be turned off C_LI

animal behavior and cognition↗

bioRxiv2024

Interactive effects of temperature acclimation and dietary fatty acids on metabolic rate and body composition of zebra finches (Taeniopygia guttata)

Climate change is contributing to geographic range shifts in many bird species, with possible exposure to novel diets. How individuals respond physiologically across chronic time frames to the interacting effects of diet and environmental temperature has been little explored. We acclimated zebra finches to either cool (20-24{degrees}C) or thermoneutral (35{degrees}C) temperatures over 6-months and provided them with diets enriched in either unsaturated or saturated fatty acids. We measured body mass throughout the study, and basal metabolic rate (BMR) and body composition at 3- and 6-months, respectively. Individuals held in cool conditions and fed a diet enriched with unsaturated fatty acids lost mass initially relative to the other groups, however, effects were reversible, and all individuals had a similar mass at 6- months. Chronic exposure to cool conditions increased BMR and the mass of the pectoral muscle and visceral organs. However, we could detect no long-term effect of diet on any physiological parameter. Our results contrast with those of birds studied over acute time frames, in which diet and temperature interact to determine energy expenditure. Over chronic time frames individuals appear to reach a new steady-state, with long-term physiological responses driven primarily by thermoregulatory responses to environmental temperature. Research HighlightsO_LIWith climate change, birds may encounter novel diets and temperatures C_LIO_LIIn zebra finches we show that chronic acclimation to cool temperatures increased energy expenditure and changed body composition. C_LIO_LIDietary fatty acid content had little long-term impact on the physiological parameters we measured. C_LI

zoology↗

bioRxiv2024

Navigating the Night: Effects of Artificial Light on the Behaviour of Atlantic Puffin Fledglings

Every year in Newfoundland, young Atlantic Puffins (Fratercula arctica) departing their nests at night for the first time become stranded in towns near their breeding colonies, a phenomenon thought to be caused by attraction toward artificial light. To test this hypothesis, we conducted three behavioural experiments. First, we illuminated beaches near a breeding colony to determine whether more fledglings would become stranded in illuminated versus dark conditions. Next, we conducted a Y-maze experiment to test stranded fledglings for phototactic behaviour in general and for preferences among High Pressure Sodium (HPS), Warm White Light-Emitting Diode (LED), Cool White LED, Blue LED, and Orange LED light. Lastly, we quantified activity levels of stranded fledglings in an open field test during exposure to several different light types. We found significantly more fledglings stranded when beaches were illuminated, and fledglings significantly preferred light over darkness in the Y-maze, supporting our hypothesis that Atlantic Puffin fledglings become stranded due to light attraction. Fledglings displayed no preferences for certain light types over others in the Y-maze, potentially suggesting that strandings in this species may not be mitigable by changing the streetlight type in stranding-prone towns. Interestingly, fledglings exhibited higher activity levels in darkness and HPS light than in LED light, potentially holding implications for rescue, rehabilitation, and husbandry programs. Overall, our findings demonstrate that the only evidence-based strategy for the reduction of Atlantic Puffin strandings remains to be the reduction of coastal artificial lighting; however, further research is needed to determine if aspects of artificial light besides bulb type may be altered to effectively reduce light attraction in this species.

animal behavior and cognition↗

bioRxiv2023

Terrestrial endotherms trade body temperature regulation for the stress response when energy is limited

Responding to perceived threats is energetically expensive and can require animals to curtail somatic repair, immunity, and even reproduction to balance energy ledgers. Among birds and mammals, energetic demands of thermoregulation are often immense, yet whether homeostatic body temperatures are also compromised to aid the stress response is unknown. Using data sourced from over 60 years of literature and 24 endotherm species, we show that exposure to non-thermal challenges (e.g. human interaction, social threats) caused body temperatures to decrease in the cold and increase in the warmth, but particularly when species-specific costs of thermoregulation were high and surplus energy low. Biophysical models revealed that allowing body temperature to change in this way liberated up to 24% (mean = 5%) of resting energy expenditure for use toward coping. While useful to avoid energetic overload, such responses nevertheless heighten risks of cold- or heat-induced damage, particularly when coincident with cold- or heat-waves.

physiology↗

bioRxiv2022

Transcriptomic responses to multigenerational environmental warming in a cold-adapted salmonid using de novo RNA sequencing

Cold-adapted species are particularly threatened by climate change as rates of environmental warming outpace the ability of many populations adapt. Recent evidence suggests that transgenerational thermal plasticity may play a role in the response of cold-adapted organisms to long-term changes in temperature. Using RNA sequencing, we explored differential gene expression of lake trout (Salvelinus namaycush), a cold-adapted species, to examine the molecular processes that respond to elevated temperatures under conditions of within-generation (offspring) and transgenerational (parental) warm acclimation. We hypothesized that genes associated with metabolism, growth and thermal stress/tolerance would be differentially expressed in juvenile lake trout offspring depending on their own acclimation temperature and that of their parents. While parental warm acclimation did have a transgenerational effect on gene expression in their offspring, within-generation (offspring) warm acclimation had a larger effect on the number of differentially expressed genes. Differentially expressed genes enriched pathways for thermal stress, signaling processes, immune function, and transcription regulation and depended on the acclimation temperature of the offspring in isolation or in combination with parental warm acclimation. We provide evidence of the transgenerational response to warming at the transcriptional level in lake trout, which should be useful for future studies of transcriptomics and plasticity in this and other cold-adapted species.

genetics↗

bioRxiv2021

Using mass Spectrometry to investigate fluorescent compounds in squirrel fur

While an array of taxa are capable of producing fluorescent pigments, fluorescence in mammals is a novel and poorly understood phenomenon. We believe that a first step towards understanding the potential adaptive functions of fluorescence in mammals is to develop an understanding of fluorescent compounds, or fluorophores, that are present in fluorescent tissue. Here we use Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) of flying squirrel fur known to fluoresce under ultraviolet (UV) light to identify potentially fluorescent compounds in squirrel fur. All of the potentially fluorescent compounds we identified were either present in non-fluorescent fur or were not present in all species of fluorescent flying squirrel. Therefore, we consider that the compounds responsible for fluorescence in flying squirrels may also be present in non-fluorescent mammal fur. Some factor currently unexplained likely leads to excitation of fluorophores in flying squirrel fur. A recently suggested hypothesis that fluorescence in mammals is widely caused by porphyrins is consistent with our findings.

ecology↗

bioRxiv2021

Within- and transgenerational plasticity of a temperate salmonid in response to thermal acclimation and acute temperature stress

Environmental temperatures associated with climate change are rising too rapidly for many species to adapt, threatening the persistence of taxa with limited capacities for thermal acclimation. We investigated the capacity for within- and transgenerational responses to increasing environmental temperatures in brook trout (Salvelinus fontinalis), a cold-adapted salmonid. Adult fish were acclimated to temperatures within (10{square}) and above (21{square}) their thermal optimum for six months before spawning, then mated in a full factorial breeding design to produce offspring from cold- and warm-acclimated parents as well as bidirectional crosses between parents from both temperature treatments. Offspring families were subdivided and reared at two acclimation temperatures (15{square} and 19{square}) representing their current environment and a projected climate change scenario. Offspring thermal physiology was measured as the rate of oxygen consumption (MO2) during an acute change in temperature (+2{square} h-1) to observe their MO2-temperature relationship. We also recorded resting MO2, the highest achieved (peak) MO2, and critical thermal maximum (CTM) as performance metrics. Within-generation plasticity was greater than transgenerational plasticity, with offspring acclimation temperature having demonstrable effects on peak MO2 and CTM. Transgenerational plasticity was evident as an elevated resting MO2 and the MO2-temperature relationship in offspring from warm-acclimated parents. Both parents contributed to offspring thermal responses, although the paternal effect was stronger. Although brook trout exhibit both within- and transgenerational plasticity for thermal physiology, it is unlikely that these will be sufficient for coping with long-term changes to environmental temperatures resulting from climate change. SummaryBrook trout (Salvelinus fontinalis) exhibit within-generation and transgenerational plasticity for thermal performance, although neither response appears sufficient to cope with long-term climate change effects.

physiology↗

bioRxiv2021

Thermal flexibility is a repeatable mechanism to cope with environmental stressors in a passerine bird

O_LIFor many vertebrates, urban environments are characterised by frequent environmental stressors. Coping with such stressors can demand that urban individuals activate energetically costly physiological pathways (e.g. the fight-or-flight response) more regularly than rural-living conspecifics. However, urban environments also commonly demand appreciable expenditure toward thermoregulation, owing to their often extreme climatic variations. To date, whether and how vertebrates can balance expenditure toward both the physiological stress response and thermoregulation, and thus persist in an urbanising world, remains an unanswered and urgent question among ecologists. C_LIO_LIIn some species, changes in body surface temperature (Ts) and peripheral heat loss (qTot) that accompany the stress response are thought to balance energetic expenditure toward thermoregulation and responding to a stressor. Thus, augmentation of stressinduced thermal responses may be a mechanism by which urban individuals cope with simultaneously high thermoregulatory and stress-physiological demands. C_LIO_LIWe tested whether stress-induced changes in Ts and qTot: (1) differed between urban- and rural-origin individuals, (2) reduce thermoregulatory demands in urban individuals relative to rural conspecifics, and (3) meet an essential first criterion for evolutionary responses to selection (variability among, and consistency within, individuals). C_LIO_LIUsing the black-capped chickadee (Poecile atricapillus; n = 19), we show that neither rapid nor chronic changes in Ts and qTot following exposure to randomised stressors differed between urban- and rural-origin individuals (nurban = 9; nrural = 10). Nevertheless, we do find that stress-induced changes in Ts and qTot are highly repeatable across chronic time periods (RTs = 0.61; RqTot = 0.67) and display signatures of stabilising or directional selection (i.e. reduced variability and increase repeatability relative to controls). C_LIO_LIOur findings suggest that, although urban individuals appear no more able to balance expenditure toward thermoregulation and the stress response than rural conspecifics, the capacity to do so may be subject to selection in some species. To our knowledge this is also the first study to report repeatability of any theorised stress-induced trade-off. C_LI

ecology↗

bioRxiv2020

Limited transgenerational effects of environmental temperatures on thermal performance of a cold-adapted salmonid

The capacity of ectotherms to cope with rising temperatures associated with climate change is a significant conservation concern as the rate of warming is likely too fast for adaptation to occur in some populations. Transgenerational plasticity, if present, could potentially buffer some of the negative impacts of warming on future generations. We examined transgenerational plasticity in lake trout to assess their inter-generational potential to cope with anticipated warming. We acclimated adult lake trout to cold or warm temperatures for several months, then bred them to produce offspring from parents of matched and mismatched temperatures. At the fry stage, offspring were also acclimated to cold or warm temperatures and their thermal performance was assessed by measuring their critical thermal maximum and metabolic rate during an acute temperature challenge. Overall, transgenerational plasticity was evident: thermal performance of offspring reflected both maternal and paternal environmental conditions, and offspring performed better when their environment matched that of their parents. There was little variation in offspring critical thermal maximum or peak metabolic rate, although cold-acclimated offspring from warm-acclimated parents exhibited elevated standard metabolic rates, suggesting that transgenerational effects can be detrimental when parent and offspring environments mismatch. These results demonstrate both the occurrence and limitations of transgenerational plasticity in a coldwater salmonid in response to elevated temperature, as well as potential ecological risks associated with transgenerational plasticity when an environmental change experienced by the parents does not persist with the next generation.

physiology↗

bioRxiv2020

A temperate endotherm trades thermoregulation for self-preservation: stress-induced changes in surface temperature as thermoregulatory trade-offs

O_LICoping with stressors can require substantial energetic investment, and when resources are limited, such investment can preclude simultaneous expenditure on other biological processes. Among endotherms, energetic demands of thermoregulation can be immense, yet whether a stress response is sufficient to induce changes in thermoregulatory investment appears unexplored. C_LIO_LIWe tested the hypothesis that stress-induced changes in surface temperature, a well-documented phenomenon across vertebrates, stem from a trade-off between thermoregulation and stress responsiveness, whereby individuals seek to reduce energetic expenditure on thermoregulation in challenging environments (the "Thermoprotective Hypothesis"). We predicted that surface temperature and dry heat loss of individuals that are resource-limited would fall under stress exposure at low ambient temperatures and rise under stress exposure at high ambient temperatures when compared with non-resource limited individuals. C_LIO_LITo test our predictions, we exposed Black-capped Chickadees to rotating stressors and control treatments (ndays/treatment = 30; paired treatments) across an ambient temperature gradient whilst remotely monitoring both feeding behaviour and surface temperature. C_LIO_LISupporting the Thermoprotective Hypothesis, our results showed that: 1) social subordinates (n = 12), who fed less than social dominants and alone suffered stress-induced declines in mass, displayed significantly larger changes in surface temperature following stress exposure than social dominants (n = 8), and 2) stress-induced changes in surface temperature significantly increased heat conservation at low ambient temperature, and heat dissipation at high ambient temperature among social subordinates alone. C_LIO_LIThese results suggest that Black-capped Chickadees adjust their thermoregulatory strategies under stress when resources are limited and support the hypothesis that stress-induced changes in temperature are functionally significant. C_LI Data Availability Statement: All data and R code used for the construction of this study are available at: https://datadryad.org/stash/share/QzmRV875_S5IYpMT0jxOYIsoO-ua0T3LX6AA9u-XpdQ.

physiology↗

bioRxiv2019

Evidence that stress-induced changes in surface temperature serve a thermoregulatory function

Changes in body temperature following exposure to stressors have been documented for nearly two millennia, however, the functional value of this phenomenon is poorly understood. We tested two competing hypotheses to explain stress-induced changes in temperature, with respect to surface tissues. Under the first hypothesis, changes in surface temperature are a consequence of vasoconstriction that occurs to attenuate blood-loss in the event of injury and serves no functional purpose per se; defined as the Haemoprotective Hypothesis. Under the second hypothesis, changes in surface temperature reduce thermoregulatory burdens experienced during activation of a stress response, and thus hold a direct functional value; here, the Thermoprotective Hypothesis. To understand whether stress-induced changes in surface temperature have functional consequences, we tested predictions of the Haemoprotective and Thermoprotective hypotheses by exposing Black-capped Chickadees (n = 20) to rotating stressors across an ecologically relevant ambient temperature gradient, while non-invasively monitoring surface temperature (eye region temperature) using infrared thermography. Our results show that individuals exposed to rotating stressors reduce surface temperature and dry heat loss at low ambient temperature and increase surface temperature and dry heat loss at high ambient temperature, when compared to controls. These results support the Thermoprotective Hypothesis and suggest that changes in surface temperature following stress exposure have functional consequences and are consistent with an adaptation. Such findings emphasize the importance of the thermal environment in shaping physiological responses to stressors in vertebrates, and in doing so, raise questions about their suitability within the context of a changing climate.\n\nSummary StatementWe provide empirical evidence for a functional value to stress-induced changes in surface temperature that is consistent with an adaptation, using a temperate endotherm (Black-capped Chickadee) as a model species.

physiology↗

bioRxiv2019

Heat dissipation capacity influences reproductive performance in an aerial insectivore

Climatic warming will likely increase the frequency of extreme weather events, which may reduce an individuals capacity for sustained activity due to thermal limits. We tested whether the risk of overheating may limit parental provisioning of an aerial insectivorous bird in population decline. For many seasonally breeding birds, parents are thought to operate close to an energetic ceiling during the 2-3 week chick-rearing period. The factors determining the ceiling remain unknown, although it may be set by an individuals capacity to dissipate body heat (the heat dissipation limitation hypothesis). To test this hypothesis, over two breeding seasons we experimentally trimmed the ventral feathers of female tree swallows (Tachycineta bicolor) to provide a thermal window. We then monitored maternal provisioning rates, nestling growth rates, and fledging success. We found the effect of our experimental treatment was context-dependent and varied with environmental conditions. Females with trimmed plumage fed their nestlings at higher rates than controls when conditions were hot and non-windy, but the reverse was true under cool and windy conditions. On average, nestlings of trimmed females were heavier than controls, and had a higher probability of fledging. We suggest that removal of a thermal constraint allowed females to increase provisioning rates, but additionally provided nestlings with a thermal advantage via increased heat transfer during maternal brooding. Our data provide partial support for the heat dissipation limitation hypothesis, and suggest that depending on weather patterns, heat dissipation capacity can influence reproductive success in aerial insectivores.

zoology↗

bioRxiv2019

Maternal glucocorticoids do not predict reproductive investment nor breeding success in a free-ranging bird.

The hormone corticosterone (CORT)) has been hypothesized to be linked with fitness, but the directionality of the relationship is unclear. The "CORT-fitness hypothesis" proposes that high levels of CORT arise from challenging environmental conditions, resulting in lower reproductive success (a negative relationship). In contrast, the "CORT-adaptation hypothesis" suggests that, during energetically demanding periods, CORT will mediate physiological or behavioural changes that result in increased reproductive investment and success (a positive relationship). During two breeding seasons, we experimentally manipulated circulating CORT levels in female tree swallows (Tachycineta bicolor) prior to egg laying, and measured subsequent reproductive effort, breeding success, and maternal survival. When females were recaptured during egg incubation and again during the nestling stage, the CORT levels were similar among individuals in each treatment group, and maternal treatment had no effect on indices of fitness. By considering variation among females, we found support for the "CORT-adaptation hypothesis"; there was a significant positive relationship between CORT levels during incubation and hatching and fledging success. During the nestling stage CORT levels were unrelated to any measure of investment or success. Within the environmental context of our study, relationships between maternal glucocorticoid levels and indices fitness vary across reproductive stages. SUMMARY STATEMENTMaternal corticosterone levels predict breeding success of female tree swallows.

zoology↗