Foraging ecology and niche overlap in pygmy (<i>Kogia breviceps</i>) and dwarf (<i>Kogia sima</i>) sperm whales from waters of the U.S. mid‐Atlantic coast

Staudinger, Michelle D.; McAlarney, Ryan J.; McLellan, William A.; Pabst, D. Ann

doi:10.1111/mms.12064

Cited by 42 publications

(31 citation statements)

References 84 publications

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“…Accordingly, the selected model for sperm whales included more dynamic variables, such as NPP and sea surface height (SSH), than that for beaked whales. Canyons and seamounts were included in the selected model for kogiids, suggesting a more restricted habitat than for the other two groups of deep‐divers, consistent with Staudinger, McAlarney, McLellan, and Ann Pabst’s () evidence of how kogiids’ feeding areas are concentrated on the deeper shelf and slope, particularly in the epipelagic and mesopelagic zones.…”

Section: Discussionsupporting

confidence: 61%

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Virgili

Authier

Boisseau³

et al. 2018

Global Ecol Biogeogr

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Aim Deep‐diving cetaceans are oceanic species exposed to multiple anthropogenic pressures including high intensity underwater noise, and knowledge of their distribution is crucial to manage their conservation. Due to intrinsic low densities, wide distribution ranges and limited presence at the sea surface, these species are rarely sighted. Pooling data from multiple visual surveys sharing a common line‐transect methodology can increase sightings but requires accounting for heterogeneity in protocols and platforms. Location North Atlantic Ocean and Mediterranean Sea. Time period 1998 to 2015. Major taxa Ziphiidae; Physeteriidae; Kogiidae. Methods About 1,240,000 km of pooled effort provided 630 sightings of ziphiids, 836 of physeteriids and 106 of kogiids. For each taxon, we built a hierarchical model to estimate the effective strip width depending on observation conditions and survey types. We then modelled relative densities in a generalized additive modelling framework. Geographical predictions were limited to interpolations identified with a gap analysis of environmental space coverage. Results Deeper areas of the North Atlantic gyre were mostly environmental extrapolation in the predictions, thereby highlighting gaps in sampling across the different surveys. For the three species groups, the highest relative densities were predicted along continental slopes, particularly in the western North Atlantic Ocean where the Gulf Stream creates dynamic frontal zones and eddies. Main conclusions Pooling a large number of surveys provided the first basin‐wide models of distribution for deep‐diving cetaceans, including several data‐deficient taxa, across the North Atlantic Ocean and the Mediterranean Sea. These models can help the conservation of elusive and poorly known marine megafauna.

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Section: Discussionsupporting

confidence: 61%

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Virgili

Authier

Boisseau³

et al. 2018

Global Ecol Biogeogr

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“…In this geographic region, both species share a high degree of dietary overlap, suggesting similarities in habitat usage (Staudinger et al . ). Given their shared deep‐diving lifestyle and similar diet, it is plausible that both kogiid species may be exposed to, and serve as hosts for, crassicaudids.…”

Section: Discussionmentioning

confidence: 97%

“…Staudinger et al . () demonstrated a high degree of dietary overlap between male and female kogiids (Pianka Index = 0.81), but this sample included immature and mature specimens of both kogiid species. This hypothesis could be tested with a more focused analysis that compared diets of mature male and female K. breviceps .…”

Section: Discussionmentioning

confidence: 99%

Prevalence and anatomic site ofCrassicaudasp. infection, and its use in species identification, in kogiid whales from the mid‐Atlantic United States

Keenan-Bateman

McLellan

Harms

et al. 2016

Marine Mammal Science

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The parasitic nematode Crassicauda sp. was initially described in kogiid whales from specimens collected within cervical tissues, uncommon sites of infection for this parasite. Crassicauda sp. has only been reported in Kogia breviceps to date, but no study has yet investigated a large sample of both kogiid species. A 15 yr record of 104 kogiid strandings (K. sima, n = 40; K. breviceps, n = 64) in North Carolina and Virginia, U.S.A. was used to determine the prevalence of Crassicauda sp. across species, within species across sex, and within sex across length and life history categories. Crassicauda sp. was confirmed to be a species‐specific parasite among kogiids infecting only K. breviceps (prevalence = 45%). Within K. breviceps, prevalence was similar (45%) in both immature and mature males, but increased from 10% in immature to 76% in mature females. This study confirmed the cervico‐thoracic distribution of the parasite, and identified a novel site of infection in a previously undescribed exocrine gland associated with the pigmented “false gill slit.” The species‐specific nature of Crassicauda sp. infection, the exocrine gland, and the distinct features of the false gill slit pigmentation associated with the gland, are all useful characters to identify kogiid species in the field.

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“…This complexity can limit our ability to interpret stable isotope results including the various niche metrics. For example, differences in resource availability and the isotopic signatures of basal sources among communities influence the positions of consumers in bivariate space Layman et al, 2007 In most isotopic studies, the foraging behaviour of individuals is unknown and inferred from the isotopic data themselves (Botta et al, 2017;Galetti et al, 2016;Gallagher et al, 2017;Sepulveda et al, 2012;Staudinger et al, 2014). Even when corrected for resource or basal (end-member) signatures (via mixing models; Newsome et al, 2007;Newsome et al, 2012;Post, 2002), niche estimates are difficult to compare among study systems.…”

Section: Discussionmentioning

confidence: 99%

“…The package also produces estimates of sampling error. Indeed, most current studies of dietary specialization, niche partitioning and competition among individuals, populations and species rely on MCP and SEA techniques to delineate isotopic niche estimates (Botta et al, ; Galetti, Rodarte, Neves, Moreira, & Costa‐Pereira, ; Gallagher, Shiffman, Byrnes, Hammerschlag‐Peyer, & Hammerschlag, ; Staudinger, McAlarney, McLellan, & Pabst, ; but see Sepulveda, Lowe, & Marra, ).…”

Section: Introductionmentioning

confidence: 99%

rKIN: Kernel‐based method for estimating isotopic niche size and overlap

Eckrich

Albeke

Flaherty

et al. 2020

Journal of Animal Ecology

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The isotopic niche of consumers represents biologically relevant information on resource and habitat use. Several tools have been developed to quantify niche size and overlap. Nonetheless, methods adapted by spatial ecologists to quantify animal home ranges can be modified for use in stable isotope ecology when data are not normally distributed in bivariate space. We offer a tool that draws on existing spatial metrics, such as minimum convex polygon (MCP) and standard ellipse area (SEA), and add novel metrics using kernel utilization density (KUD) estimators to measure isotopic niche size and overlap. We present examples using empirical and simulated data to demonstrate the performance of the package kernel isotopic niches in r (rKIN) under various scenarios. Results of niche size from MCP, SEA and KUD were highly correlated but divergent among datasets. Overall, the KUD method produced the largest niche sizes and was more sensitive to the distribution of the isotopic data. Pairwise estimates of overlap were highly variable, likely because MCP and SEA inherently include or exclude unused areas in the resulting niche estimate. Four bandwidth methods (reference, normal scale, plug‐in and biased cross‐validation) produced comparable estimates of niche size and overlap at various sample sizes (10–40). Niche size and overlap were consistent across sample sizes >15. Use of rKIN will allow isotope ecologists to quantify niche shifts, expansions or contractions, as well as assess the performance of several estimation methods. The package also can be applied to other data types (e.g. principal component analysis, multi‐dimensional scaling) so long as axes and measurement units are identical and can be converted to Cartesian coordinates.

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Foraging ecology and niche overlap in pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales from waters of the U.S. mid‐Atlantic coast

Cited by 42 publications

References 84 publications

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Combining multiple visual surveys to model the habitat of deep‐diving cetaceans at the basin scale

Prevalence and anatomic site ofCrassicaudasp. infection, and its use in species identification, in kogiid whales from the mid‐Atlantic United States

rKIN: Kernel‐based method for estimating isotopic niche size and overlap

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