Knowledge of baleen whales' reproductive physiology is limited and requires long-term individual-based studies and innovative tools. We used 6 years of individual-level data on the Pacific Coast ...Feeding Group gray whales to evaluate the utility of faecal progesterone immunoassays and drone-based photogrammetry for pregnancy diagnosis. We explored the variability in faecal progesterone metabolites and body morphology relative to observed reproductive status and estimated the pregnancy probability for mature females of unknown reproductive status using normal mixture models. Individual females had higher faecal progesterone concentrations when pregnant than when presumed non-pregnant. Yet, at the population level, high overlap and variability in progesterone metabolite concentrations occurred between pregnant and non-pregnant groups, limiting this metric for accurate pregnancy diagnosis in gray whales. Alternatively, body width at 50% of the total body length (W50) correctly discriminated pregnant from non-pregnant females at individual and population levels, with high accuracy. Application of the model using W50 metric to mature females of unknown pregnancy status identified eight additional pregnancies with high confidence. Our findings highlight the utility of drone-based photogrammetry to non-invasively diagnose pregnancy in this group of gray whales, and the potential for improved data on reproductive rates for population management of baleen whales generally.
As ecosystems transform under climate change and expanding human activities, multidisciplinary integration of empirical research, conceptual frameworks and modelling methods is required to predict, ...monitor and manage the cascading effects on wildlife populations. For example, exposure to anthropogenic noise can lead to changes in the behaviour and physiology of individual marine mammals, but management is complicated by uncertainties on the long‐term effects at a population level. We build on a decade of diverse efforts to demonstrate the strengths of integrating research on multiple stressors for assessing population‐level effects. Using the case study of blue whales exposed to military sonar in the eastern north Pacific, we model how behavioural responses and environmental effects induced by climate change affect female survival and reproductive success. Environmental changes were predicted to severely affect vital rates, while the current regime of sonar activities was not. Simulated disturbance had a stronger effect on reproductive success than adult survival, as predicted by life‐history theory. We show that information on prey resources is critical for robust predictions, as are data on baseline behavioural patterns, energy budgets, body condition and contextual responses to noise. These results will support effective management of the interactions between sonar operations and blue whales in the study area, while providing pragmatic guidance for future data collection to reduce key uncertainties. Our study provides important lessons for the successful integration of multidisciplinary research to inform the assessment of the effects of noise and other anthropogenic stressors on marine predator populations in the context of a changing environment.
We build on a decade of multidisciplinary efforts to demonstrate the strengths of integrating research on multiple stressors for assessing population‐level effects, using the case study of blue whales exposed to military sonar and environmental changes in the eastern north Pacific. Environmental changes were predicted to severely affect female survival and reproductive success, while the current regime of sonar activities was not. We show that information on prey resources is critical for robust predictions, as are data on baseline behavioural patterns, energy budgets, body condition, and contextual responses to noise.
Habitat-use and distribution models are essential tools of conservation biology. For wide-ranging species, such models may be challenged by the expanse, remoteness and variability of their habitat, ...these challenges often being compounded by the species’ mobility. In marine environments, direct observations and sampling are usually impractical over broad regions, and instead remotely sensed proxies of prey availability are often used to link species abundance or foraging behaviour to areas that are expected to provide food consistently. One source of food consumed by many marine top predators is fisheries waste, but habitat-use models rarely account for this interaction. We assessed the utility of commercial fishing effort as a covariate in foraging habitat models for northern fulmars
Fulmarus glacialis
, a species known to exploit fisheries waste, during their summer breeding season. First, we investigated the prevalence of fulmar-vessel interactions using concurrently tracked fulmars and fishing vessels. We infer that over half of our study individuals associate with fishing vessels while foraging, mostly with trawl-type vessels. We then used hidden Markov models to explain the spatio-temporal distribution of putative foraging behaviour as a function of a range of covariates. Persistent commercial fishing effort was a significant predictor of foraging behaviour, and was more important than commonly used environmental covariates retained in the model. This study demonstrates the effect of commercial fisheries on the foraging distribution and behaviour of a marine top predator, and supports the idea that, in some systems, incorporating human activities into distribution studies can improve model fit substantially.
Between‐individual variation in phenotypes within a population is the basis of evolution. However, evolutionary and behavioural ecologists have mainly focused on estimating between‐individual ...variance in mean trait and neglected variation in within‐individual variance, or predictability of a trait. In fact, an important assumption of mixed‐effects models used to estimate between‐individual variance in mean traits is that within‐individual residual variance (predictability) is identical across individuals. Individual heterogeneity in the predictability of behaviours is a potentially important effect but rarely estimated and accounted for. We used 11 389 measures of docility behaviour from 1576 yellow‐bellied marmots (Marmota flaviventris) to estimate between‐individual variation in both mean docility and its predictability. We then implemented a double hierarchical animal model to decompose the variances of both mean trait and predictability into their environmental and genetic components. We found that individuals differed both in their docility and in their predictability of docility with a negative phenotypic covariance. We also found significant genetic variance for both mean docility and its predictability but no genetic covariance between the two. This analysis is one of the first to estimate the genetic basis of both mean trait and within‐individual variance in a wild population. Our results indicate that equal within‐individual variance should not be assumed. We demonstrate the evolutionary importance of the variation in the predictability of docility and illustrate potential bias in models ignoring variation in predictability. We conclude that the variability in the predictability of a trait should not be ignored, and present a coherent approach for its quantification.
Appropriate management of the effects of human activities on animal populations requires quantification of the rate at which animals encounter stressors. Such activities are heterogeneously ...distributed in space, as are the individual animals in a population. This will result in a heterogeneous exposure rate, which is also likely to vary over time. A spatially explicit analysis of individual exposure is therefore required. We applied Bayesian spatially explicit capture–recapture models to photo‐identification data to estimate the home range of well‐marked individuals in a protected coastal population of bottlenose dolphins. Model results were combined with the estimated distribution of boat traffic to quantify how exposure to this disturbance varied in time and space. Variability in exposure between individuals was also investigated using a mixed‐effects model. The cumulative individual exposure to boat traffic varied between summers, depending both on the overall area usage and the degree of individual movement around the activity centres. Despite this variability, regions of higher risk could be identified. There were marked inter‐individual differences in the predicted amount of time dolphins spent in the presence of boats, and individuals tended to be consistently over‐ or underexposed across summers. Our study offers a framework to describe the temporal, spatial and individual variation in exposure to anthropogenic stressors when individuals can be repeatedly identified over time. It provides opportunities to map exposure risk and understand how this evolves in time at both individual and population levels. The outcome of such modelling can be used as a robust evidence base to support management decisions.
Sperm whalePhyseter macrocephalushabitat preferences are still poorly understood in the Mediterranean, despite the population being classified as ‘Endangered’ by the IUCN. Techniques to make the best ...use of multiple data sources are important in improving this situation. This work provides a detailed evaluation of sperm whale distribution and habitat use around the Balearic Islands using a novel analytical framework that combines transect and follow data while accounting for any autocorrelation present. During dedicated research cruises (2003 to 2008), sperm whales were located by listening at regular intervals along a search track and subsequently followed acoustically. Sperm whales were encountered 56 times and followed for periods ranging from a few hours to 3 d. Logistic Generalized Additive Models were used to model the probability of whale presence across the study area as a function of environmental variables, and Generalized Estimating Equations were used to account for autocorrelation. The results suggest that sperm whales do not use the region uniformly and that topography plays a key role in shaping their distribution. Moreover, solitary individuals were found to use the habitat differently from groups. This segregation appeared to be driven by water temperature and might reflect different needs or intraspecific competition. By shedding light on sperm whale habitat preference in such a critical area, this study represents an important step towards the implementation of conservation measures for this population.
Ecological niche is traditionally defined at the species level, but individual niches can vary considerably within species. Research on intra-specific niche variation has been focussed on intrinsic ...drivers. However, differential transmission of socially learned behaviours can also lead to intra-specific niche variation. In sperm whales Physeter macrocephalus, social transmission of information is thought to generate culturally distinct clans, which at times occur sympatrically. Clans have distinct dialects, foraging success rates, and movement patterns, but whether the niches of clan members are also different remains unknown. We evaluated the differences in habitat use of clans off the Galápagos Islands, using data collected over 63 encounters between 1985 and 2014. During encounters, we recorded geographic positions, determined clan identity through analysis of group vocalizations and individual associations, and used topographical and oceanographic variables as proxies of sperm whale prey distribution. We used logistic generalized additive models, fitted with generalized estimating equations to account for spatiotemporal autocorrelation, to predict clan identity as a function of the environment descriptors. Oceanographic variables marginally contributed to differentiating clans. Clan identity could be predicted almost entirely based on geographic location. This fine-scale, within-region spatial partitioning likely derives from whales preferring areas where members of their clans occur over temporal scales of a few months to a few years. By identifying differences in clans’ space use, we have uncovered another level of sperm whale life that is likely influenced by their cultural nature.
Sexual segregation is common among marine mammals, leading to intraspecific differences in diet, diving behaviour, home range size and even latitudinal distribution and migratory patterns. Sperm ...whales Physeter macrocephalus present one of the most extreme examples of sexual dimorphism both in size and social structure, with males and females segregating at different latitudes across most of their range, but the underlying ecological drivers remain unclear. Studying fine-scale dietary and habitat differences where the sexes occur in sympatry could therefore provide insights into the mechanisms underpinning their large-scale segregation. In this study, we analysed the carbon and nitrogen stable isotope values in the skin of males and females from an isolated, endangered population inhabiting the Mediterranean Sea, sampled in a region where the sexes occur and feed regularly in the summer months but show subtle differences in habitat preference. We found marked differences in both carbon and nitrogen isotopic values between the sexes, indicating that they could be targeting prey items in different trophic levels and habitats. Combined with the evidence from habitat modelling studies, our results suggest that female and male sperm whales segregate even in the latitudinally restricted Mediterranean population, at a much smaller scale. This sympatric, fine-scale sexual segregation suggests that reduction of competition may have been a key factor in the evolution of the social structure and large-scale latitudinal segregation of this species.
Predicting the distribution and behaviour of animals is a fundamental objective in ecology and a cornerstone of conservation biology. Modelling the distribution of ocean-faring species like seabirds ...remains a significant challenge due to ocean dynamics, colony-specific effects and the vast ranges seabirds can cover. We used a spatial and behavioural approach to model the distribution of the Manx shearwater Puffinus puffinus, a pelagic, central-place forager that can cover great distances while foraging. GPS data from birds tagged in 2 colonies over 3 yr were modelled with a range of environmental predictors of marine productivity. For both colonies, transitions to foraging behaviour correlated with chlorophyll a, and the distribution of foraging behaviour was also associated with areas of high chlorophyll a concentration in coastal but not offshore areas for one colony. Furthermore, there was evidence for colony differences in habitat use, prevalence of nocturnal foraging, and for some competitive exclusion on foraging grounds, even though the colonies were 170 km apart. Despite the extensive dataset, our models had modest predictive power, which we suggest can probably only be improved by including biotic interactions, including more direct measures of food resource distribution. Our results highlight the importance of in - cluding spatial complexity and data from multiple sites when predicting the distribution of wideranging predators, because patterns of distribution and habitat use likely differ across the range of a population.
An investigation of the potential of Maltese MSW (Municipal solid waste) for energy recovery is carried in this work together with a preliminary assessment of the corresponding economic and land use ...impacts. MSW composition data was collected to evaluate the waste combustion enthalpy. Data from 1997 to 2010 allowed the conclusion that an incinerator with a capacity of 32,500 kg/h can treat all the waste expectably generated in Malta during next 20 years. The thermodynamics of the steam cycle combined with elemental analysis was applied to study the contribution for PG (power) and CHP (combined heat and power) generation. The thermal energy was analyzed assuming its use in desalination. The best scenario considered corresponds to a potential electric power of 10 MW (PG) or to a maximum 4.8 million m3/year of desalinated water combined with and 7.25 MW (CHP). It was concluded that incineration and CHP have the greatest potential to maximize revenues, due to the optimal combination of heat production and electricity generation. Finally, a calculation of the savings in land use due to the MSW incineration implementation was performed. Those savings could represent from 13,500 to 17,000 m2 per year, a decisive benefit for Malta.
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