Body Condition Index Research Articles

Somatic and population adaptations of <i>Polysarcus denticauda</i> (Orthoptera) in extreme altitudes

Altitudinal preferences, somatic and population adaptations in different ecological conditions were analysed in flightless bush-cricket species Polysarcus denticauda (Charpentier, 1825). Altitudinal analysis was performed in GIS software (more than 60 sites in Slovakia, Central Europe). Seasonal occurrence and population density were recorded in selected sites. To compare differences, absolute values of measurements (length of body, hind femur and tibia, cerci and weight) and Body Condition Index were taken from males. Study species prefers mesophilous montane up to alpine meadows in higher elevations (over 600 m a.s.l.). The development started over one month earlier in lowlands and populations reached several fold higher density there. Males from lowlands had body parameters significantly bigger apart from cerci. Cerci were significantly longer in males from mountains. However, males of the same size were significantly heavier in higher altitudes. In conclusion, refuges of montane meadows ecosystem support species survival nowadays.

Vocalisation and its association with androgens and corticosterone in a night frog (Nyctibatrachus humayuni) with unique breeding behaviour

AbstractIn anurans, vocalisation is used to communicate within and between the sexes during reproduction. Knowledge of vocal repertoire and its diversity is essential in understanding its significance in sexual selection. In this context, we studied the vocal behaviour of Nyctibatrachus humayuni and quantified the urinary metabolites of androgens and corticosterone to understand the associations among hormones, body condition index and vocalisation. Our results show that males of N. humayuni produce an amplitude‐modulated call consisting of a train of pulses. Interestingly, a high degree of inter‐individual variation was observed in the call parameters. The dominant frequency and pulse interval were negatively correlated with male body size, whereas pulse duration and pulse duty cycle were positively correlated with it. Dominant frequency was negatively correlated with androgens and corticosterone, whereas pulse interval was negatively correlated with corticosterone. Further, pulse duty cycle, pulse duration and pulses per call were positively associated with corticosterone. Surprisingly, none of the acoustic parameters was associated with male body temperature and body condition. A significant variation was evident in the vocal effort, dominant frequency and amplitude of advertisement calls produced under different social situations. Calls produced during territory establishment had lower dominant frequency but higher vocal effort, whereas those produced during courtship had higher amplitude and vocal effort than the calls produced in the absence of a competitor/female. Our results suggest that greater inter‐male variability in the advertisement call of N. humayuni could be important in female choice as it may help females to assess the quality of a male. Further, androgens and corticosterone could be important in modulating crucial parameters of the advertisement call.

Influence of Commercial and Laboratory Diets on Growth, Body Composition, and Reproduction in the Zebrafish Danio rerio.

The value of the zebrafish (Danio rerio) as a model organism continues to expand. In developing the model, current feeding practice in zebrafish laboratories includes the use of commercially available diets. In this study, we compared outcomes in growth, body composition, and reproduction among zebrafish fed five highly utilized commercial diets and one formulated chemically defined reference diet. Wild-type zebrafish larvae were raised on live feed until 21 days postfertilization and then fed diets for 16 weeks. All fish received a daily ration of >5% of body weight (adjusted biweekly). Growth varied among diets throughout the feeding trial, and at study termination (week 16), significant differences among diets were observed for terminal weight gain, body condition index, body fat deposition, and reproductive outcomes. In addition, the proportion of viable embryos produced from females fed the formulated reference diet was high relative to the commercial diets. These data suggest that metabolic profiles, most likely reflecting nutrient/energy availability, utilization, and allocation, vary relative to diet in zebrafish. Undefined differences in metabolic profiles could result in erroneous predictions of health outcomes and make comparisons among laboratories more challenging. We recommend that dietary standards should be defined for zebrafish to support their common utility in biomedical research.

Winter corticosterone and body condition predict breeding investment in a nonmigratory bird

AbstractReproduction is an energetically demanding life history stage that requires costly physiological and behavioral changes, yet some individuals will invest more into reproduction and breed more successfully than others. To understand variation in reproductive investment, previous studies have evaluated factors during breeding, but conditions outside of this life history stage may also play a role. Using a free-ranging population of black-capped chickadees (Poecile atricapillus), we assessed the repeatability of plastic traits relating to energetic condition (circulating initial corticosterone concentrations and body condition) during the nonbreeding season and evaluated whether these traits predicted reproductive investment in the subsequent breeding season. We found that initial corticosterone concentrations and an index of body condition, but not fat score, were moderately repeatable over a 1-week period in winter. This trait repeatability supports the interpretation that among-individual variation in these phenotypic traits could reflect an intrinsic strategy to cope with challenging conditions across life history stages. We found that females with larger fat reserves during winter laid eggs sooner and tended to spend more time incubating their eggs and feeding their offspring. In contrast, we found that females with higher residual body mass delayed breeding, after controlling for the relationship between fat score and timing of breeding. Additionally, females with higher initial corticosterone in winter laid lighter eggs. Our findings suggest that conditions experienced outside of the breeding season may be important factors explaining variation in reproductive investment.

Seasonal and temporal variation in scaled mass index of Black-capped Chickadees (<i>Poecile atricapillus</i>)

Avian body mass reflects a trade-off between risk of starvation and predation, and may vary with ambient temperature, age, and time of day. Seasonal variability in body mass is a common occurrence in northern temperate regions, including adaptive fattening. Previous evidence suggests that seasonal variability is less pronounced in tree-feeding bird species, as their food sources during winter are less limited and variable compared to ground-foraging species. We determined fat scores of tree-feeding Black-capped Chickadees (Poecile atricapillus) captured year-round between 2004 and 2015 (n = 4248) in southern Quebec, to test the relative strength of possible drivers of variability in chickadee body mass, including time, date, and year of capture, age, and temperature. First, we demonstrated that scaled mass index (SMI) was the body condition index, out of four possible indices tested, which most strongly correlated with fat scores measured in the field. We used SMI subsequently as our estimator of body condition to avoid observer effects associated with fat scores. Similar to other studies, time of capture significantly affected SMI, in which birds captured later were heavier, indicating that chickadees experience overnight weight loss and subsequent weight gain from foraging throughout the day. SMI was constant from April to November, then peaked in late winter, but was not influenced by daily temperature after accounting for month and year. SMI was not significantly affected by age. We concluded that adaptive fattening is an evolutionary response to risk of starvation in winter, rather than a proximal response to immediate ambient temperature.

Time‐keeping programme can explain seasonal dynamics of leukocyte profile in a migrant bird

It has been proposed that immune functioning in wild animals is shaped by the trade‐off between a probability of encountering pathogens and an availability of resources for maintaining immune system in active state. Due to resources’ seasonality one can expect that immune functioning, e.g. absolute and relative counts of white blood cells, WBC (leukocyte profile) also follows an annual cycle. However, dynamics of the seasonal changes of leukocyte profile are controversial and specific inquiries so far addressed only a portion of annual cycle. To study the seasonal dynamics of the leukocyte profile and to test its possible endogenous basis we experimentally simulated annual cycle in a migratory passerine bird, chiffchaff Phylloscopus collybita abietinus. We report here a clear seasonal pattern of leukocyte profile in that species. The highest WBC counts were observed during pre‐alternate moult and the lowest during the subsequent spring migration; the seasonal dynamics of HL ratio showed the opposite tendency. Surprisingly, HL ratios during autumn migration were relatively low, indicating little to no stress. Observed seasonal changes in controlled experimental conditions suggest an existence of time‐keeping programme underlying these variations. Additionally we found negative relationship between the body condition index and WBC counts and positive relationship with HL (heterophil to lymphocyte) ratio; these findings are controversial with the data obtained with other bird species in wild populations. Understanding the origins of variation of leukocyte profile per se and in relation with other parameters of physiological condition can be a useful tool in studying physiological response to environmental changes.

Migration distance does not predict blood parasitism in a migratory songbird.

Migration can influence host–parasite dynamics in animals by increasing exposure to parasites, by reducing the energy available for immune defense, or by culling of infected individuals. These mechanisms have been demonstrated in several comparative analyses; however, few studies have investigated whether conspecific variation in migration distance may also be related to infection risk. Here, we ask whether autumn migration distance, inferred from stable hydrogen isotope analysis of summer‐grown feathers (δ 2Hf) in Europe, correlates with blood parasite prevalence and intensity of infection for willow warblers (Phylloscopus trochilus) wintering in Zambia. We also investigated whether infection was correlated with individual condition (assessed via corticosterone, scaled mass index, and feather quality). We found that 43% of birds were infected with Haemoproteus palloris (lineage WW1). Using generalized linear models, we found no relationship between migration distance and either Haemoproteus infection prevalence or intensity. There was spatial variation in breeding ground origins of infected versus noninfected birds, with infected birds originating from more northern sites than noninfected birds, but this difference translated into only slightly longer estimated migration distances (~214 km) for infected birds. We found no relationship between body condition indices and Haemoproteus infection prevalence or intensity. Our results do not support any of the proposed mechanisms for migration effects on host–parasite dynamics and cautiously suggest that other factors may be more important for determining individual susceptibility to disease in migratory bird species.

Food subsidies of raccoons (Procyon lotor) in anthropogenic landscapes

Food subsidies from human sources are often exploited by free-ranging vertebrates living in human-dominated landscapes. To explore the importance and attempt to estimate the reliance of raccoons (Procyon lotor (Linnaeus, 1758)) — common synanthropes in North America — on such food subsidies, we analyzed hair samples from 122 raccoons collected across four states in the Midwestern United States (Wisconsin, Minnesota, Iowa, and Illinois), including 9 raccoons that were livetrapped and sampled in Madison (Wisconsin). We found that raccoons inhabiting areas with more agriculture had higher δ13C values, indicating a diet enriched with anthropogenic food from C4 photosynthetic plants, like corn (Zea mays L.). Surprisingly, raccoons inhabiting increasingly urban areas showed lower δ13C values, suggesting a diet with less anthropogenic food. Regardless, raccoons in urban areas enriched in 13C possessed high indices of body condition, suggesting that anthropogenic food subsidies are contributing to their overall nutritional condition. Our findings reveal that the degree to which synanthropes rely upon human foods differs by land-cover type and that the use of these calorically rich subsidies has important implications on individual health.

Life is uncertain, eat dessert first: feeding ecology and prey-predator interactions of the coffee snake Ninia atrata

ABSTRACTPrey-predator interactions are considered one of the primary drivers of the ecology and evolution of several vertebrate taxa, but particularly, it has played a significant role in the evolutionary biology of snakes. However, feeding ecology of semifossorial tropical snakes has been poorly studied. We employed a multivariate approach to explore the effects of sexual dimorphism, prey-predator interaction, and climatic variability due to El Niño–Southern Oscillation (ENSO) on the abundance and feeding ecology of the semifossorial snake Ninia atrata. Climatic variability analysis revealed conspicuous temporal variation in the prey availability at microhabitat, as well as in the snake abundance and food intake. Multivariate approach provided strong support for links between Ninia atrata abundance, microhabitat quality and snails abundance (more than other prey). Conspicuous intersexual dietary divergence was observed supporting the hypothesis of the sex-specific targets for maximum food intake. ENSO phenomenon promoted a notable decline in Ninia atrata abundances and its food intake, which was related to prey availability and abundance, as well as a strong variability on their body condition index (BCI). Finally, given the high sensitivity of Ninia atrata to the environmental variability, it could consider an indicator species of the environmental changes in the Neotropical oil palm agroecosystems.

Wild bumble bee foraging preferences and fat content in highbush blueberry agro-ecosystems

Agricultural intensification can impact the availability and quality of resources. We analyzed resource use by bumble bees (Bombus spp.), important pollinators of highbush blueberry (Vaccinium corymbosum), collected from conventional highbush blueberry farms, organic highbush blueberry farms, and nearby natural areas in the lower Fraser River valley of British Columbia, Canada. We identified corbicular pollen and measured bee fat content as an indicator of body condition. Bumble bees use non-crop resources, including pollen from plant species not found on farms. Bees from natural areas had higher pollen protein content in corbicular pollen and higher body fat content than those from conventional and organic farms. There was no difference between farm types, and we could not demonstrate a relationship between pollen protein and bee fat content. Our findings illustrate the importance of resource availability throughout agro-ecological landscapes, including not only farms but also off-farm areas.

Transgressive niche across a salamander hybrid zone revealed by microhabitat analyses

AbstractAimHybrid populations can have intermediate, conserved or transgressive niches, compared to the parental species. Fine‐scale analyses can improve our understanding of niche evolution, but information on microhabitat differences between parental species and hybrids is extremely scarce for animal populations. We assessed the pattern and role of niche variation along a hybrid zone, by investigating differences in microhabitat selection between terrestrial cave salamander species (Hydromantes ambrosiiandHydromantes italicus) and their hybrids. We tested whether introgressed populations show intermediate, conserved or transgressive niche, compared to parental species. Furthermore, we compared body condition index (BCI) among individuals observed in different microhabitats (different areas of caves), to assess the potential advantages of exploiting specific microhabitats.LocationWe surveyed ~700 cave sectors in Italy, across the whole range of the two parental species and along their contact zone.MethodsWe recorded salamander distribution and measured microhabitat features influencing salamander distribution: humidity, temperature and incident light. We tested niche differences between parental species and hybrids, and analysed spatial variation of body condition.ResultsWe detected significant niche shifts between parental species and hybrids. Introgressed populations showed a transgressive niche and exploited sectors with warmer temperature, lower humidity and more light, compared to the non‐introgressed ones. Introgressed salamanders were better able to exploit the microhabitat conditions that are frequently found nearby cave entrance. For males, BCI was significantly higher in individuals found close to the cave entrance.Main conclusionsThe transgressive niche of hybrids betweenH. ambrosiiandH. italicusindicates niche expansion towards harsh environmental conditions, and such transgressive segregation allows exploiting environments with higher food availability. The ability to exploit dry and warm sectors can provide important advantages to hybrid populations that can better persist under stressful conditions. Transgressive niche can be important for long‐term persistence and evolution within hybrid zones.

Body mass index and glucose variations during the night in free-ranging Artibeus planirostris (Chiroptera: Phyllostomidae)

Body condition is an important measure to estimate the energy reserve of an organism. Scientists frequently use body condition indices (BCIs) with morphometric measures but direct measurements, such as blood glucose, seem to be more reliable. We observed oscillations in the body condition and glucose indexes of individuals ofArtibeusplanirostris(Spix, 1823) during 13 nights in the field. We assume that if glucose levels are proportional to feeding state and body condition is a measure of energy reserve, blood glucose and BCI should be positively correlated and both are expected to increase during the night as the bats leave their diurnal roost to feed. To test this, we examined the relationship between blood glucose levels, BCI and reproductive phase of free flying male bats (n = 70) for 12 hours after sunset for 13 nights. Bats were captured in Reserva Biológica de Guaribas (Paraíba, Brazil) using mist nets. Blood glucose was analyzed with a portable glucometer. Supporting our assumptions, the number of hours after sunset and BCI presented significant positive correlations with glucose levels inA.planirostris. Reproductive phase did not present a significant correlation with any other variables. As we predicted, glucose level can be used as proxy for morphometric BCI and it can be measured with a simple portable glucometer. The increase both in glucose and BCI around the night can be explained by the efficient assimilation of nutrients present in fruits ingested by bats and the quick metabolism that increases the levels of glucose (an other nutrients) in blood, increasing the body mass.

A comparison of body condition of the yellowstriped butterfish Labracoglossa argenteiventris in relation to parasitism by the cymothoid isopod Ceratothoa arimae

Isopods of the genus Ceratothoa (Cymothoidae) are one of the largest invertebrates parasitic on a variety of fishes, which include commercially important species. Nevertheless, the parasitic effects on fish body condition have been studied only in a few Ceratothoa species, particularly those living in the Mediterranean and Australian waters. Findings from these previous studies suggest the hypothesis that effects of parasitism by Ceratothoa species are benign on native host condition in the wild. In this study, to test this hypothesis on another Ceratothoa–fish relationship in different region, we examined the effects of Ceratothoa arimae on the body condition of the yellowstriped butterfish, Labracoglossa argenteiventris, a commercial fish important to local fisheries particularly in the remote islands of Tokyo, Japan. Ceratothoa arimae was found in 8 out of 23 fish examined (prevalence: 34.8%). Although infected and uninfected fish were similar in standard length, the body condition index (relative weight) of infected fish was significantly lower than that of uninfected fish. The observed weight of infected fish was an average of 89.2% of the expected weight. These results are inconsistent with the hypothesis and suggest that the potential effects of Ceratothoa parasites need to be considered carefully in fishery management plan of host fish.

Community reestablishment and poor body conditions of small mammal assemblages in subtropical afforested ecosystems

Afforestation is one of the high-efficiency practices for the restoration of degraded forest ecosystems and has been increasingly used worldwide. It is crucial to determine the restoration status of wildlife in afforested forests to effectively monitor biodiversity conservation and the self-sustainability of forest ecosystems, as well as to effectively guide the implementation of afforestation projects in the future. China has the largest area of man-made forests around the world, but the effects of the restoration efforts on the faunal diversity in artificial woodlands are unclear. Here, we evaluated the effects of afforestation practices on small mammals in two types of planted forests: Japanese larch (Larix kaempferi, an introduced species) and China Armand pine (Pinus armandii, a native species) plantations, and two reference forests: young- and old-growth forests, at the community, population, and individual levels. The diversity of small mammals did not differ significantly among the four forest types and the population densities of small mammals in two plantations were between the young- and old-growth forests. Collectively, our findings indicated that small mammal assemblages had reestablished in afforested forests. Four body condition indices were measured in the Chinese white-bellied rat (Niviventer confucianus), a predominant species, and differences were found between afforested and reference forests. Chinese white-bellied rats had the lowest body masses and highest endoparasite loads in the Japanese larch planted forest, while body length or carcass mass did not differ among the four forest types. In comparison, study rats had slightly lower body masses and lower endoparasite loads in the China Armand pine planted forest than reference forests. These findings indicated that small mammals inhabiting both types of afforested forests had poor body conditions but these trends were worse in the Japanese larch planted forest, i.e., the introduced species. Given that afforestation is a widespread practice for global forest landscape restoration, we propose two suggestions to guide afforestation efforts and the subsequent management thereof: (1) native species rather than exotic species are preferable for use in afforestation projects, and (2) wildlife diversity in afforested forests should be considered when monitoring the restoration and management of degraded forest ecosystems.

Genetic evaluation of a 15-year selection program for high growth in striped catfish Pangasianodon hypophthalmus

This study attempted to make a comprehensive genetic evaluation of a selective breeding program for striped catfish Pangasianodon hypophthalmus selected for high growth over 15 years from 2001 to 2015. Statistical analyses were carried out on 54,259 individual fish that were offspring of 554 sires and 926 dams (955 families in total). Both univariate and bivariate linear animal mixed models were used to estimate variance and covariance components for four groups of traits studied: (i) body traits (harvest body weight and standard length), (ii) carcass traits (fillet weight and fillet yield), (iii) fish body condition (condition index) and (iv) growth survival of each individual during grow-out phase. Medium to high heritability (0.31–0.54) were estimated for body traits, while carcass and condition index had medium heritability (0.17 to 0.20). Phenotypic and genetic correlations among body traits (weight and length) were high and close to one. The growth-related traits showed moderate and positive (i.e., favourable) genetic correlations with fillet yield (0.67–0.92) and condition index (0.28–0.49). Direct response to selection for high growth was 9.3% per generation. The selection program increased fillet weight and growth survival by 8.5% and 7.4%, respectively. However, there was insignificant correlated change in fillet yield (only 1.6%). Collectively, our results showed that there are substantial genetic variations in all traits studied and selection for high growth resulted in beneficial changes in fillet weight, fish body condition and survival during grow-out phase. The improved strain of striped catfish had 13.4% greater growth performance than their wild counterparts of the latest generation, suggesting that culture of the improved striped fish line may enhance productivity and economic return for small householder farmers and commercial producers.

Does carnivory pay off? Experiments on the effects of different types of diet on growth and development of Bufo bufo (Linnaeus, 1758) tadpoles and carry-over effects after metamorphosis

Natural diets of anuran larvae vary widely in their relative amounts of nutrients. The proportion of these ingested nutrients has significant influence on larval and post-metamorphic performance. Here, we use the Common Toad to address the role of diet (exclusively carnivore, exclusively vegetarian and mixed) on growth and development of tadpoles and short-term carry-over effects on post-metamorphic animals. Larvae fed on an exclusively vegetarian diet performed better (faster growth and development) than larvae fed on exclusively carnivore and mixed diets. Larvae fed on the exclusively carnivore diet had the lowest performance. Regarding the carry-over effects of larval diets, although the body condition indices of the toadlets were similar in all treatments, there was a major difference in the survival rate. While toadlets, originating from larvae fed on a vegetarian diet, were more successful and had the lowest mortality, those fed on a carnivore diet had the highest mortality level. Our results suggest that a plant-based diet may contain all the necessary nutrients needed by Bufobufo larvae. Furthermore, a diet based exclusively on food of animal origin might be detrimental for the larval performance and could have significant carry-over effects on the post-metamorphic animal.

Reproductive Techniques for Ovarian Monitoring and Control in Amphibians.

Ovarian control and monitoring in amphibians require a multi-faceted approach. There are several applications that can successfully induce reproductive behaviors and the acquisition of gametes and embryos for physiological or molecular research. Amphibians contribute to one-quarter to one-third of vertebrate research, and of interest in this context is their contribution to the scientific community's knowledge of reproductive processes and embryological development. However, most of this knowledge is derived from a small number of species. In recent times, the decimation of amphibians across the globe has required increasing intervention by conservationists. The captive recovery and assurance colonies that continue to emerge in response to the extinction risk make existing research and clinical applications invaluable to the survival and reproduction of amphibians held under human care. The success of any captive population is founded on its health and reproduction and the ability to develop viable offspring that carry forward the most diverse genetic representation of their species. For researchers and veterinarians, the ability to monitor and control ovarian development and health is, therefore, imperative. The focus of this article is to highlight the different assisted reproductive techniques that can be used to monitor and, where appropriate or necessary, control ovarian function in amphibians. Ideally, any reproductive and health issues should be reduced through proper captive husbandry, but, as with any animal, issues of health and reproductive pathologies are inevitable. Non-invasive techniques include behavioral assessments, visual inspection and palpation and morphometric measurements for the calculation of body condition indices and ultrasound. Invasive techniques include hormonal injections, blood sampling, and surgery. Ovarian control can be exercised in a number of ways depending on the application required and species of interest.

Brood sex ratio and nestling physiological condition as indicators of the influence of weather conditions on breeding black storks Ciconia nigra

Abstract In species with sexual dimorphism, raising female or male offspring may be associated with different costs and benefits, resulting in a skewed nestling sex ratio. We examined the influence of: weather conditions, hatching date and brood size on nestling sex ratio in the black stork Ciconia nigra. We used molecular methods to determine the sex of 284 nestlings. Samples were collected during a 12-years study in central Poland. The overall nestling sex ratio was skewed towards females (61%), which are smaller, and presumably easier to raise than males. Delayed hatching date significantly increased the proportion of female nestlings. Warmer temperatures in the pre-breeding season were correlated with lower proportions of males. This is probably mediated by the influence of weather on water levels in black stork foraging sites. The second most important weather trait was total rainfall in May, the month in which the majority of nestlings hatch. Total May rainfall was negatively correlated with the percentage of male offspring. We used blood haemoglobin concentration as an indicator of body condition in a subsample of 122 nestlings. The males from the study population had lower blood haemoglobin concentrations, indicating their poorer body condition and supporting the hypothesis that they are the more vulnerable sex. We also observed that blood haemoglobin concentration of nestlings is lower in late broods. Deteriorating body condition of late offspring can explain the observed increase in female nestling proportions in delayed broods.

Body condition indicators: Assessing the influence of harvest location and potential thresholds for application in beluga monitoring

• Sex-specific beluga body condition models account for size, age, location, and year. • Belugas from entrapment events can serve as thresholds for body condition indicators. • Spatial variability was detected and requires consideration in the use of indicators. • This study aims to develop blubber thickness and girth as body condition indicators. Monitoring marine protected areas requires simplifying complex marine ecosystems into a suite of indicators. The Tarium Niryutait Marine Protected Area (TN MPA), the first MPA in the Canadian Arctic is located in the Inuvialuit Settlement Region, NT and is selecting indicators for monitoring. Proposed health indicators for the TN MPA species of interest, the Eastern Beaufort Sea (EBS) beluga, include the body condition metrics blubber thickness and girth. Sex-specific body condition models for both metrics were developed to account for age, size, location, and timing of harvest from belugas harvested from 2000 to 2015. Models were tested to determine if the spatial variation is detected in the condition of belugas between the three areas of the TN MPA and between belugas harvested inside to outside of the TN MPA. Lastly, we assessed belugas from entrapment events to determine if indicator thresholds could be developed. Three of the indicators (girth male, girth female, blubber thickness male) contain both temporal and spatial factors, signalling the significant influence of year and harvest location on condition. Male belugas harvested from the western area of the TN MPA had smaller mean blubber thickness and girth compared to the other TN MPA areas, whereas there was no significant difference in female condition across the TN MPA. There was a significant difference inside and outside the TN MPA for all four indicators, with larger mean blubber thickness inside the TN MPA, females exhibiting larger mean girth and males exhibiting smaller mean girth inside the TN MPA. Indicators confirm that belugas from entrapment events had significantly lower body condition than belugas harvested during the summer and can serve as thresholds for condition indicators. This study provides guidance on the selection and use of condition indicators for their application in monitoring the TN MPA and demonstrates that careful consideration is required for indicator development and selection.

Coastal songbird condition on migratory stopover varies by geographical location and bird age

Abstract The period of migration can pose significant energetic challenges as birds attempt to reach their destinations. Suitable stopover habitat is, therefore, important to the success of migrating individuals, especially as they move along major migration corridors and geographic features, like coastlines. In this study, we used metrics of individual body condition (i.e. fat score, size-corrected body mass, and refueling rate) of fall migrants as they moved across the Gulf of Maine region, a complex coastal landscape. We investigated the extent to which these body condition indices varied by stopover site geography (island vs. mainland) and how these spatial patterns varied with species-specific characteristics such as migratory distance, foraging guild, and age. Geography was an important factor explaining variation in all 3 condition indices, and age explained additional variance in 2 of the 3. In general, individuals captured on islands exhibited significantly lower energetic condition than individuals on the mainland, and this pattern held true across all migratory strategies and foraging guilds. Immature individuals had, on average, lower energy reserves, with less fat and lower size-corrected mass than adults among all stopover sites. We also found that at all sites, size-corrected body mass, on average, significantly increased over the capture day, providing evidence that both island and mainland sites provided energetically beneficial stopover habitat. Our finding that birds offshore are in lower body condition at capture than those along the coast is suggestive that birds use mainland sites for longer stopover bouts than island sites, or that poorer condition birds reorient to land during over-water movements disproportionately use off-shore islands as their initial landing area. Decreases in either island or mainland stopover site availability or quality may affect individual fitness, with population-level consequences, but through different ways.