Foraging Habitat Preferences Research Articles

Legacy persistent organic pollutants among multiple cetacean species in the Northwest Atlantic

The historical contamination of eastern Canadian shelf waters remains an ongoing concern, predominantly stemming from anthropogenic discharges in the Great Lakes region. Although legacy persistent organic pollutants (POPs) were banned decades ago, it remains unclear whether their concentrations have sufficiently decreased to safer levels in cetaceans that feed in the continental shelf waters of the northwestern Atlantic. This study compares polychlorinated biphenyl (PCB) and organochlorine pesticide (OC) accumulation in six cetacean species sampled in the Northwest Atlantic from 2015 to 2022. We assessed the influence of relative trophic level and foraging habitat preferences on POP accumulations among species using stable isotopes and fatty acids as dietary tracers. We further identified the species most susceptible to the effects of these contaminants. Killer whales (Orcinus orca) exhibited the highest PCB (∼100 mg/kg lw) and OC concentrations, followed by other odontocetes, with lowest concentrations in mysticetes. Stable isotope analysis revealed an unexpected lack of correlation between δ15N values and contaminant levels. However, there was a positive correlation between δ13C values and POP concentrations. Cetaceans foraging on pelagic prey species, as indicated by elevated proportions of the FA markers 22:1n11 and 20:1n9, had lower contaminant loads compared to cetaceans with benthic/coastal FA signatures. PCB and DDT (dichlorodiphenyltrichloroethane) concentrations are lower now in most cetacean species than in the 1980s and 1990s, likely due to regulatory measures restricting their production and use. Although current PCB concentrations for most species are under the thresholds for high risks of immune and reproductive failure, concentrations in killer whales exceed all established toxicity thresholds, underscoring the need for further action to reduce sources of these contaminants to the continental shelf waters of the northwestern Atlantic.

Offshore vagrancy in passerines is predicted by season, wind-drift, and species characteristics

BackgroundMigratory birds accomplish remarkable feats of long-distance navigation. Vagrants, few individuals who migrate to incorrect locations, reveal conditions where orientation and navigation fail. Studies of vagrancy on a continental scale reveal the importance of external factors such as strong winds driving birds off course, clouds obscuring migratory landmarks, and natural disruptions in the Earth’s magnetic field interfering with migratory orientation. Species may also possess characteristics that make them more prone to vagrancy. The external drivers of vagrancy on a smaller scale are less understood.MethodsI used eBird, a community science dataset comprising millions of bird observations, to study land passerines observed over the Pacific Ocean, here termed offshore vagrants. These data present the opportunity to study a particular case of vagrancy: small-scale displacement into highly inhospitable areas. I modeled how season, wind, lack of visibility, interference with magnetoreception, and species differences may predict offshore vagrancy. Then, I modeled how species vagrancy likelihood is predicted by morphological and life history traits.ResultsVagrancy was more common in the fall and positively associated with stronger tail winds in the spring. Species with greater preference for understory foraging habitat were less likely to occur as vagrants. Species vagrancy likelihood was higher in birds with a longer migration distance and rounded wings, but the relationship was weaker in birds with a pointed wings. Brown-headed Cowbirds were the most common offshore species in terms of absolute number of records and proportional to onshore frequency.ConclusionsOffshore community science records proved revealing of mechanisms for small scale vagrancy in passerines. Offshore vagrancy can be driven by wind drift in the spring, but not in the fall despite higher overall levels of vagrancy. Life history characteristics like foraging habitat preference and migration duration may make some species more vulnerable to the effects of wind drift. Species with longer migrations may have more time to encounter vagrancy causing events, but greater aerodynamic efficiency may counteract this effect.

Comparable foraging effort and habitat use between two geographically proximate tropical seabird colonies

Effective seabird conservation requires understanding their marine spatial ecology. Tracking can reveal details of their foraging ecology and habitat use, as well as the suitability of marine protected areas for at-sea conservation, but results are often regionally specific. Here we characterised the foraging behaviour of tropical breeding brown boobies Sula leucogaster in the Chagos Archipelago, Western Indian Ocean, and tested habitat requirements. GPS tracking of thirteen individuals from two colonies, located 142 km apart on the same atoll (Great Chagos Bank), showed similar foraging effort and habitat preferences despite differences in season and breeding stage. Brown boobies from both tracked populations foraged close to the colony along the atoll shelf edge, avoiding deep oceanic areas and shallow waters of the Great Chagos Bank atoll, but within the Chagos Archipelago Marine Protected Area. Sea-level height anomaly and sea surface temperature were important foraging predictors at both sites, although birds experienced distinct environmental conditions between colonies. These results suggest that while brown boobies have colony-specific at-sea foraging areas, similarities in habitat drivers of distribution and foraging behaviour can inform predictions of distributions at other colonies within the archipelago, with important benefits for at-sea conservation efforts.

Habitat preferences of Phoebetria albatrosses in sympatry and allopatry

AbstractAimCompetition is often proposed to drive niche segregation along multiple axes in speciose communities. Understanding spatial partitioning of foraging areas is particularly important in species that are constrained to a central place. We present a natural experiment examining variation in habitat preferences of congeneric Southern Ocean predators in sympatry and allopatry. Our aim was to ascertain consistency of habitat preferences within species, and to test whether preferences changed in the presence of the congener.LocationSouthern Hemisphere.TaxonMultiple colonies of both species within the genus Phoebetria (sooty albatrosses).MethodsThe two Phoebetria albatrosses breed on islands located from ~37–55°S – sooty albatrosses (P. fusca) in the north and light‐mantled albatrosses (P. palpebrata) in the south – with sympatric overlap at locations ~46–49°S. We analysed GPS and PTT tracks from 87 individuals and multiple remotely sensed environmental variables using GAMs, to determine and compare the key factors influencing habitat preference for each species at each breeding colony.ResultsWhile foraging habitat preferences are consistent in light‐mantled albatrosses, there is divergence of preferences in sooty albatrosses depending on whether they are in sympatry with their congener or in allopatry.Main ConclusionsThis study represents the most comprehensive work on this genus to date and highlights how habitat preferences and behavioural plasticity may influence species distributions under different competitive conditions.

Targeting fin whale conservation in the North-Western Mediterranean Sea: insights on movements and behaviour from biologging and habitat modelling.

Biologging and habitat modelling are key tools supporting the development of conservation measures and mitigating theeffects of anthropogenic pressures on marine species. Here, we analysed satellite telemetry data and foraging habitat preferences in relation to chlorophyll-a productivity fronts to understand the movements and behaviour of endangered Mediterranean fin whales (Balaenoptera physalus) during their spring-summer feeding aggregation in the North-Western Mediterranean Sea. Eleven individuals were equipped with Argos satellite transmitters across 3 years, with transmissions averaging 23.5 ± 11.3 days. Hidden Markov Models were used to identify foraging behaviour, revealing how individuals showed consistency in their use of seasonal core feeding grounds; this was supported by the distribution ofpotential foraging habitat. Importantly, tracked whales spent most of their time in areas with no explicit protected status within the study region. This highlights the need for enhanced time- and place-based conservation actions to mitigate the effects of anthropogenic impacts for this species, notably ship strike risk and noise disturbance in an area of exceptionally high maritime traffic levels. These findings strengthen the need to further assess critical habitats and Important Marine Mammal Areas that are crucial for focused conservation, management and mitigation efforts.

Comparative analysis of trophic niche using stable isotopes provides insight into resource use of giant pandas.

Trophic niche is the result of the long-term evolution of species and can reflect the pressures they experience in habitats. The whole-genome sequencing of giant pandas (Ailuropoda melanoleuca) has indicated that populations distributed in Qinling (QIN) and non-QIN probably diverged 300 ky ago. Although many studies regarding foraging strategy, habitat preference, and niche partition have been conducted on these populations, there is still a lack of precise quantification of trophic niches. Here, we calculated and compared isotopic trophic niche widths of giant pandas from Sichuan (SC) and QIN populations by measuring carbon and nitrogen isotopes of their hairs; combined with data from sympatric mammals, we explored the relative trophic positions of giant pandas in the ecosystem, respectively. The Stable Isotope Bayesian Ellipses in R (SIBER) model results showed the trophic niche width of QIN pandas was 3.44‰2 , which was significantly bigger than those of the SC population (2.03‰2 ), with an overlapping about 1.45‰2 ; and they both occupied a unique position in the context, almost one trophic level lower than herbivores. Then, we determined the isotopic ratios of the main foods from the habitats of these pandas; the results suggested that the isotopic difference between bamboo shoots and other parts plus the various feeding selections of pandas on them accounted for pandas' trophic niche widths. We considered the higher nutrition availability and digestible food resources giving QIN pandas a wider trophic niche than pandas from SC. This conclusion provides a new insight into the resource use and trophic ecology of giant pandas and is important to develop refined management plans for the two populations.

Finding food in a changing world: Small-scale foraging habitat preferences of an insectivorous passerine in the Alps.

Organisms living in high-elevation habitats are usually habitat specialists who occupy a narrow ecological niche. To envision the response of alpine species to a changing environment, it is fundamental to understand their habitat preferences on multiple spatial and temporal scales. However, information on small-scale habitat use is still widely lacking. We investigated the foraging habitat preferences of the migratory northern wheatear Oenanthe oenanthe during the entire presence at a breeding site in the central Alps. We repeatedly observed 121 adult and juvenile individuals. We applied Bayesian logistic regression models to investigate which habitat characteristics influenced foraging habitat selection on a fine spatial scale, and how habitat use varied temporally. Throughout their presence on the breeding grounds, northern wheatears showed a consistent preference for a mosaic of stones and bare ground patches with slow-growing, short vegetation. The proximity of marmot burrows was preferred, whereas dense and low woody vegetation was avoided. After arrival at the breeding site, short vegetation, preferably close to the snow, was favored. The preference for open habitat patches that provide access to prey underlines the critical role of small-scale habitat heterogeneity for northern wheatears. The strong and consistent preference for a habitat that is under pressure from land-use and climate change suggests that this alpine bird species may be sensitive to habitat loss, leading to a potential range contraction. We highlight the need to conserve habitat diversity on a small spatial scale to ensure the long-term availability of suitable habitat for northern wheatears in the Alps.

When a pest-control species becomes a pest: A shift in the foraging habitat of cattle egret (Bubulcus ibis) and the threat to grazed natural ecosystems

Ecosystem services such as natural pest control and pollination may benefit agriculture, but may also adversely affect adjacent ecosystems. Here, we explored the cosmopolitan cattle egret (Bubulcus ibis), a commensal insectivorous large bird which has been expanding worldwide and is often considered as a pest control agent. We assessed the changes in the distribution of this new resident and its nesting and foraging habitat preferences in Mediterranean agroecosystems in northern Israel over the last few decades. We evaluated the relative importance of reptile, amphibian and arthropod prey in its diet by analysing regurgitated food in nesting colonies, and modelled the effect of land-use on reptile prey composition. We found that a recent expansion of B. ibis has been facilitated by the introduction of cattle grazing to natural habitats, and by augmentation of human-dominated landscapes and crop fields. Arthropods have dominated the egret diet (73.75 %), but the overwhelming proportion of reptile species (19.67 %) comprises predominantly maquis dwellers, indicating high predation pressure in natural rangelands. Although B. ibis acts as an agricultural pest control agent in croplands, its function as a harmful predator in grazed natural habitats seems to be substantial. Such intrusion of a novel predator into natural ecosystems may have catastrophic implications for native fauna, particularly in human-dominated and fragmented landscapes. Our findings underscore the potential adverse effects of a naturally thriving predator on local fauna and the importance of further research to understand its actual impact on both agricultural pests and non-pest prey communities in the wild.

The effects of river regulation on diet diversity, dietary niche overlap and foraging habitat preferences of two sympatric plover species

During migration waders use a variety of microhabitats and a wide range of prey to supply their nutritional requirements. Most of them form multispecies flocks, which may result in increased competition for resources. In this study, we compare the abundance of potential prey for Ringed and Little Ringed plovers at unregulated and regulated stretches of the Vistula River. We also observed plovers and assigned them to the habitat in which they foraged and compare the diet, dietary niche overlap and foraging habitat preferences of these two plover species. The larger species, the Ringed Plover, foraged more often in invertebrate abundant habitats, yet exclusively on the three most abundant prey species, while the smaller species expanded its diet to include invertebrate species of low abundance and in suboptimal habitats. In the regulated river section, below the dam, the diet of the Little Ringed Plover was more diverse, and the dissimilarity of both plovers’ diets was much higher than in the regulated section. The unregulated river section offered richer foraging grounds and both species showed similar proportions of primary prey items in their diets here resulting in greater dietary niche overlap and weaker resource partitioning. Our study shows that river regulation increases competition for food resources due to a lower abundance of potential prey and has an influence on diet diversity and foraging habitat preferences of smaller, less competitive plover species.

Foraging distances, habitat preferences and seasonal colony performance of honeybees in Central European forest landscapes

Abstract Unmanaged forest is considered as native habitat of the Western honeybee Apis mellifera and is assumed to provide important pollen and nectar sources. However, resource supply might be spatially and temporally restricted in managed forests and landscape‐scale studies in European forest regions are currently lacking. Capitalizing on a unique communication behaviour, the waggle dance, we investigated honeybee foraging in a deciduous forest region in southern Germany. We analysed 2022 waggle dances performed by bees of 12 colonies placed in the centre of landscapes with varying degree of forest cover (50%–99% at a 2‐km radius) from March to August 2019, thereby identifying foraging distances and habitat preferences over almost an entire foraging season. By connecting dance information with colony weight recordings, we assessed the role of landscape composition and the contribution of different habitat types to colony weight gain. Foraging distances generally increased with the amount of forest in the surrounding landscape pointing to inferior food resources in the forest. Yet, this effect strongly depended on the season and was more pronounced for pollen than for nectar foraging. Even though colonies in forest‐dominated landscapes had to fly further, colony weight was not significantly affected by forest cover. Compared to expectations based on the proportions of different habitats, colonies foraged more frequently in grassland and cropland than in deciduous and coniferous forests, with late summer being an especially difficult period for pollen foraging in forests. During a phase of colony weight gain in early summer, the use of forests for nectar/honeydew foraging was close to the expectation, highlighting forests as an important complementary source of carbohydrates during short periods of the year. Policy implication. The ecological and economic value of managed forest as habitat for honeybees could be significantly increased by the continuous provision of floral resources, especially for pollen foraging. Therefore, we recommend diversifying forest stands with insect‐pollinated trees, permitting secondary successions in forest gaps, and at larger scales, creating forest landscapes with high habitat diversity. This will not only help native, wild‐living honeybees and beekeepers' colonies residing in forest areas but will also foster social bees in general.

Differences in foraging range between white-tailed tropicbirds breeding on inner and outer Seychelles islands

The foraging ecology and distribution of Phaethontiformes, an order of tropical seabirds, remains generally poorly understood, despite being essential to inform their conservation. Here, we tracked, for the first time, the foraging movements of breeding white-tailed tropicbirds Phaethon lepturus, a common but poorly studied seabird, in the Indian Ocean. We compared the foraging movements and habitat preferences of 2 populations, one from Aride Island in the inner Seychelles and the other from Aldabra Atoll in the outer Seychelles, ca. 1200 km to the southwest. We found considerable differences in foraging trip metrics between populations, with birds from Aride having an average foraging range 2 times greater (231 km on Aride vs. 105 km on Aldabra), and both populations feeding far beyond the protected areas around their respective colony. We also found differences in foraging range between incubation and chick-rearing stages and sexes. Using habitat models, we highlight the birds’ preference for deep waters, which may explain the greater foraging range of Aride birds, although human activities may also play a role. Our study provides unprecedented insight into the foraging ecology of white-tailed tropicbirds in the Western Indian Ocean.

Consistent foraging habitat use by a vulnerable breeding seabird highlights potential areas for protection in the mid-Atlantic Ocean

Identifying animal foraging habitat can help prioritise areas for conservation and enable better predictions of how populations respond to environmental change. Recent reductions in the size of biologging devices now enable fine-scale foraging habitat tracking for very small seabirds. We investigated the foraging distribution and habitat preferences of Monteiro’s storm-petrel Hydrobates monteiroi, a tiny (<60 g), vulnerable seabird that is endemic to the Azores Archipelago. We tracked 67 storm-petrels with 108 GPS deployments across 4 consecutive breeding seasons (2018-2021) to identify important foraging areas and preferences for dynamic and static features of their mid-ocean environment. We found that static bathymetric features such as seafloor depth and distance from the nearest seamount were the most important predictors of foraging location, suggesting that topographic features may provide areas of enhanced biological productivity in the mid-Atlantic Ocean that are predictable across long timescales. Although dynamic oceanographic variables (sea surface temperature and chlorophyll a) also helped predict foraging activity, both the location and environmental characteristics of foraging habitat were relatively stable across 4 consecutive years. This suggests that meso-scale oceanographic dynamics do not drive strong interannual variation in foraging behaviour in this system. Currently, only 11.4% of Monteiro’s storm-petrel foraging locations overlap with designated marine protected areas. A total of 95% of unprotected foraging locations fell within the Azores exclusive economic zone (EEZ), indicating a responsibility of the Portuguese government to increase habitat protection. Our findings suggest that more comprehensive at-sea conservation for this vulnerable species could be focused in predictable geographic areas over the mid-Atlantic ridge and seamounts.

A comparison of foraging‐range sizes, flight distances and foraging habitat preferences in urban and rural House Sparrow (Passer domesticus) populations

Lack of food for nestlings is a crucial factor influencing population size and dynamics in birds. It is one of the most cited reasons for recent House Sparrow Passer domesticus population declines in cities and rural settlements. However, a detailed comparative study of habitat use by parents delivering food to offspring in different environments is still missing. To obtain the most detailed information on fine‐scale foraging habitat selection, foraging‐range size, flight distance and foraging duration in typical Central European urban and rural environments, we conducted systematic observations of colour‐ringed focal individuals feeding their offspring. We found that urban House Sparrows had larger foraging‐range sizes and longer foraging distances than rural birds. Additionally, some preferred habitats, such as ruderal and woody vegetation, occurred less frequently in the urban area and consequently increased flight distance to key sources of invertebrate prey. In both environments, the most selected habitats – bin storage areas and poultry holdings – offered a stable and rich but probably lower quality ‘fast food’ source. Birds were willing to fly a longer distance to forage at bin storage areas, tall ruderal vegetation and poultry holdings. Our findings imply that natural food sources in the urban environment are scarce and scattered. Due to the improvement of socio‐economic status associated with better handling of waste products in both urban and rural environments, sprawl of highly urbanized areas and intensification of farming, important foraging habitats have thus decreased. We highlight the importance of maintaining suitable small‐ and medium‐scale farms in rural areas and suggest improvements in the management of green spaces in all types of human settlements that may support House Sparrow populations.

Food for everyone: Differential feeding habits of cryptic bat species inferred from DNA metabarcoding.

Ecological theory postulates that niches of co‐occurring species must differ along some ecological dimensions in order to allow their stable coexistence. Yet, many biological systems challenge this competitive exclusion principle. Insectivorous bats from the Northern Hemisphere typically form local assemblages of multiple species sharing highly similar functional traits and pertaining to identical feeding guilds. Although their trophic niche can be accessed with unprecedented details using genetic identification of prey, the underlying mechanisms of resource partitioning remain vastly unexplored. Here, we studied the differential diet of three closely‐related bat species of the genus Plecotus in sympatry and throughout their entire breeding season using DNA metabarcoding. Even at such a small geographic scale, we identified strong seasonal and spatial variation of their diet composition at both intra‐ and interspecific levels. Indeed, while the different bats fed on a distinct array of prey during spring, they showed higher trophic niche overlap during summer and fall, when all three species switched their hunting behaviour to feed on few temporarily abundant moths. By recovering 19 ecological traits for over 600 prey species, we further inferred that each bat species used different feeding grounds and hunting techniques, suggesting that niche partitioning was primarily habitat‐driven. The two most‐closely related bat species exhibited very distinct foraging habitat preferences, while the third, more distantly‐related species was more generalist. These results highlight the need of temporally comprehensive samples to fully understand species coexistence, and that valuable information can be derived from the taxonomic identity of prey obtained by metabarcoding approaches.

Intersexual segregation in winter foraging of great spotted woodpecker Dendrocopos major in riparian forests infested with invasive tree species

ABSTRACT We investigated the pre-breeding intersexual foraging habitat preferences of the great spotted woodpecker Dendrocopos major in six old, unmanaged riparian forest stands in Central Hungary, which are composed mainly of the invasive North American green ash Fraxinus pennysylvanica and boxelder Acer negundo, and native poplar Populus sp. and willow Salix sp. trees in lower abundances. With the influence of river management, the two invasive species have usurped native tree species in numerous Central European riparian forests. We studied the intersexual utilization of tree species, tree condition, stem diameter, foraging height, horizontal sections, substrate diameter, substrate condition, and foraging technique. The birds showed intersexual segregation in numerous studied variables despite the high niche overlap between sexes. Similar patterns were also found in other woodpecker species as well. We think that the most important part of this segregation could be the difference revealed in the choice of tree species, as males tended to be more specialized for native softwood tree species with rougher bark structure. Despite the high abundance of invasive tree species, neither sex preferred them. The further population decrease of native tree species could increase within-species competition and negatively affect the studied bird species.

Assessing the relative importance of managed crops and semi-natural grasslands as foraging habitats for breeding lesser kestrels Falco naumanni in southeastern Italy

Farmland habitats host important populations of several threatened bird species. So far, how to reconcile farmland management with the maintenance of viable populations of these taxa is a major challenge for conservation biology. Southeastern Italy hosts ca 7000 pairs of breeding lesser kestrels Falco naumanni, representing one of the European strongholds of this small colonial raptor of conservation concern. We firstly assessed the relative importance of managed crops versus semi-natural grasslands in determining the local abundance of lesser kestrels at the landscape scale, and we successively studied the foraging habitat preferences at a smaller spatial scale. Surveys of foraging birds were associated with land-use collection at 191 homogeneous habitat sampling parcels from 14 plots of 16 km2 each, uniformly distributed over a 2400 km2 area. Each plot was visited six times during the 2017 breeding season (May–July). Land-use markedly changed along the season, unripe cereals being dominant in May, while harvested cereal crops prevailed in July. Land-use did not affect lesser kestrel distribution early in the season while foraging birds were more abundant in plots with a greater proportion of harvested cereal crops and a lower one of semi-natural grassland in the late breeding season. In accordance, the analysis of foraging habitat preferences within plots showed that in May unripe cereal crops and semi-natural grasslands were used proportionally to their availability. In June and July, harvested cereal crops were used more than expected from their availability, while semi-natural grasslands were significantly avoided. Our landscape-scale analysis thus indicates that semi-natural grasslands are much less used in comparison to harvested crops during the mid and late parts of the breeding season, suggesting that lesser kestrel may be able to take advantage of crop management practices more than other farmland birds of conservation priority.

Foraging in a dynamic environment: Response of four sympatric sub-Antarctic albatross species to interannual environmental variability.

Seasonal and annual climate variations are linked to fluctuations in the abundance and distribution of resources, posing a significant challenge to animals that need to adjust their foraging behavior accordingly. Particularly during adverse conditions, and while energetically constrained when breeding, animals ideally need to be flexible in their foraging behavior. Such behavioral plasticity may separate “winners” from “losers” in light of rapid environmental changes due to climate change. Here, the foraging behavior of four sub‐Antarctic albatross species was investigated from 2015/16 to 2017/18, a period characterized by pronounced environmental variability. Over three breeding seasons on Marion Island, Prince Edward Archipelago, incubating wandering (WA, Diomedea exulans; n = 45), grey‐headed (GHA, Thalassarche chrysostoma; n = 26), sooty (SA, Phoebetria fusca; n = 23), and light‐mantled (LMSA, P. palpebrata; n = 22) albatrosses were tracked with GPS loggers. The response of birds to environmental variability was investigated by quantifying interannual changes in their foraging behavior along two axes: spatial distribution, using kernel density analysis, and foraging habitat preference, using generalized additive mixed models and Bayesian mixed models. All four species were shown to respond behaviorally to environmental variability, but with substantial differences in their foraging strategies. WA was most general in its habitat use defined by sea surface height, eddy kinetic energy, wind speed, ocean floor slope, and sea‐level anomaly, with individuals foraging in a range of habitats. In contrast, the three smaller albatrosses exploited two main foraging habitats, with habitat use varying between years. Generalist habitat use by WA and interannually variable use of habitats by GHA, SA, and LMSA would likely offer these species some resilience to predicted changes in climate such as warming seas and strengthening of westerly winds. However, future investigations need to consider other life‐history stages coupled with demographic studies, to better understand the link between behavioral plasticity and population responses.

Allometry and Ontogeny in the Vertebral Column of Southern Hemisphere Dolphins: a 3D Morphofunctional Approach

Commerson’s dolphin (Cephalorhynchus commersonii), Peale’s dolphin (Lagenorhynchus australis), dusky dolphin (Lagenorhynchus obscurus), and hourglass dolphin (Lagenorhynchus cruciger) are closely related species occurring in the Southern Hemisphere. Even though they are partially sympatric, they have evolved towards diverse foraging strategies, prey, and habitat preferences. Size variation occurs both among and within species. Our goal was to study the allometric patterns and ontogenetic trajectories in the vertebral column of these dolphins related to their ecology. We choose nine functionally homologous vertebrae in each column and digitized five different tridimensional configurations, containing 28 to 41 landmarks depending on the functional region under analysis. We explored different levels of allometry (static, ontogenetic, and evolutionary) using multivariate regressions of shape vs. log-transformed centroid size. We compared ontogenetic allometry regression vectors to evidence differences in growth patterns. Finally, we calculated Procrustes distances of shape configurations to determine the timing of shape shifts. Of the studied species, When compared to the Lagenorhynchus species, Commerson’s dolphin showed the highest degrees of allometry, both static and ontogenetic. The macroevolutive trends indicate a high degree of evolutionary morphological change, which could be associated with the rapid evolutionary radiation proposed for the group. This is the first time that allometric changes are studied in small cetaceans by means of 3D geometric morphometrics.

Seasonal distribution and foraging occurrence of Cook Inlet beluga whales based on passive acoustic monitoring

A paucity of information on the basic biology and ecology of Cook Inlet beluga whalesDelphinapterus leucasremains a decade after the species was listed as endangered in 2008. The causes of its continued decline remain unclear. This lack of knowledge limits our understanding of, and ability to manage, potential threats impeding the recovery of this endangered population. Seasonal distribution and foraging ecology, particularly during winter, are currently among the most basic gaps in knowledge. Therefore, we conducted a year-round passive acoustic monitoring program from 2008-2013, monitoring 13 locations within the belugas’ critical habitat. We identified seasonal occurrence patterns across years at most locations. Detections were higher in the upper inlet during summer, peaking in known concentration areas. The occurrence of whales in the upper inlet when ice coverage peaked during winter was more prevalent than previously suggested. We documented seasonal differences in foraging habitat preference, with foraging behavior more prevalent during summer, particularly near upper inlet rivers, than during winter. Foraging peaks coincided with the presence of different anadromous fish runs from spring to fall. Low levels of feeding activity in winter suggest a lack of feeding aggregation areas, feeding in non-monitored offshore waters, or increased effort on benthic prey. These results represent a substantial contribution to our knowledge of Cook Inlet beluga seasonal distribution and foraging ecology, which will strengthen conservation and management strategies and thus more effectively promote recovery of this endangered population.

Dietary composition and foraging habitats of the Indian Pangolin (Manis crassicaudata) in a tropical lowland forest-associated landscape in southwest Sri Lanka

The Indian pangolin (Manis crassicaudata) has a wide distribution in the Indian subcontinent and is a threatened species throughout its range due to hunting, poaching, trafficking, and destruction of natural habitats. Many rescue programmes for Indian pangolins have had limited success due to the paucity of literature on the diet, ecology and its behaviour. This study investigated the dietary composition and foraging habitat preference of the Indian pangolin in a tropical lowland forest-associated landscape of Southwest Sri Lanka. Five types of habitat were considered in this study: forest, rubber plantation, cinnamon cultivation, oil palm plantation, and tea-dominated home gardens/cultivated areas. The foraging intensity of Indian pangolin in the five habitat types was assessed using signs of foraging activities observed in five 10 × 10 m plots placed along a transect. Ten transects were established in each habitat assessed. The forest habitat was preferred in the studied landscape, followed by rubber plantations, the cinnamon cultivations, oil palm plantations and the tea-dominated home gardens/cultivated areas. Indian pangolins mostly predated on termites, as indicated by the number of feeding events on termitaria and termite-infested logs. Faecal content analysis further revealed that the undigested matter (by weight) was predominantly composed of grit (53.3%), insect matter (37%) and plant matter (9.7%). The digestibility of termite heads, mouthparts, abdomens, and legs was high compared to that of ants. This difference in digestibility was evident from the presence of significantly more heads, mouthparts, abdomens, and legs of ants in the faecal matter, compared to that of termites. However, undigested termite wings were frequently observed in the faecal matter. Termites of the genus Odontotermes and ants of the genera Oecophylla, Anoplolepis, Camponotus and Monomorium were the main prey species of the Indian pangolin in the studied area. The findings on the dietary composition have implications in captive rearing and husbandry of Indian pangolins. In addition to natural forests, the findings of the study suggest that human-modified agricultural lands adjoining forest also serve as important as foraging habitats for Indian pangolins, and such habitats should be considered in long-term conservation planning.