The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula
Describing the foraging dynamics of apex predators is crucial to understanding ecosystem function and to effective conservation and management. Leopard seals are conspicuous apex predators in Antarctic coastal ecosystems; however, their foraging ecology is poorly understood. Likely due to a geograph...
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ftcdlib:qt7mp1s7bw 2023-05-15T13:57:18+02:00 The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula Krause, Douglas 216 2016-01-01 application/pdf http://www.escholarship.org/uc/item/7mp1s7bw http://n2t.net/ark:/13030/m5cz7vxj en eng eScholarship, University of California http://www.escholarship.org/uc/item/7mp1s7bw qt7mp1s7bw http://n2t.net/ark:/13030/m5cz7vxj public Krause, Douglas. (2016). The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula. UC San Diego: Oceanography. Retrieved from: http://www.escholarship.org/uc/item/7mp1s7bw Biological oceanography Ecology Biology animal behavior apex predator foraging ecology leopard seal stable isotope unmanned aerial systems dissertation 2016 ftcdlib 2016-09-16T22:55:06Z Describing the foraging dynamics of apex predators is crucial to understanding ecosystem function and to effective conservation and management. Leopard seals are conspicuous apex predators in Antarctic coastal ecosystems; however, their foraging ecology is poorly understood. Likely due to a geographical redistribution driven by pack-ice habitat reduction in the western Antarctic Peninsula, leopard seals have been hauling out at Cape Shirreff with increasing frequency in recent years. Utilizing that rare access we implemented an integrated sampling design including morphometrics, biological samples, and bio-logger deployments in January and February between 2008 and 2014. Subsequently, we quantified foraging behavior using: k-means cluster (diving), time-local convex hulls (movement), Bayesian stable isotope mixing models (diet), and linear regression (mass estimation) analyses. While they are typically described as generalist apex predators, video, dive, and movement data suggest they employ specialized foraging patterns. They affect coastal ecosystems through pathways beyond direct predation, including intraspecific kleptoparasitism, predator-induced stress effects, facultative scavenging and food caching. Leopard seal diving behavior is concentrated at night, is both shallow and coastal, and is composed of four distinct dive types. Haul-out probabilities were highest near midday and were positively correlated with available daylight. Video, scat and stable isotope analyses indicate that their summer diet contains four prey groups: Antarctic fur seals, pygoscelid penguins, krill, and demersal notothen fishes. Finally, measurements of body size and mass are fundamental to pinniped population management and research. The recent proliferation of unmanned aerial systems (UAS) in wildlife monitoring has provided a promising new platform for the photogrammetry of free-ranging pinnipeds. Photogrammetric measurements from a single, vertical image obtained using UAS were as accurate as ground measures, and provide a noninvasive approach for estimating the mass and body condition of pinnipeds. This dissertation provides substantial insight into the hunting tactics, foraging behavior, and diet of large adult female leopard seals and provides a viable option for future monitoring. Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctic Fur Seals Antarctic Peninsula Hydrurga leptonyx Leopard Seal Leopard Seals Livingston Island University of California: eScholarship Antarctic Antarctic Peninsula Cape Shirreff ENVELOPE(-60.800,-60.800,-62.417,-62.417) Hydrurga ENVELOPE(-61.626,-61.626,-64.145,-64.145) Livingston Island ENVELOPE(-60.500,-60.500,-62.600,-62.600) Shirreff ENVELOPE(-60.792,-60.792,-62.459,-62.459) |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Biological oceanography Ecology Biology animal behavior apex predator foraging ecology leopard seal stable isotope unmanned aerial systems |
spellingShingle |
Biological oceanography Ecology Biology animal behavior apex predator foraging ecology leopard seal stable isotope unmanned aerial systems Krause, Douglas The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula |
topic_facet |
Biological oceanography Ecology Biology animal behavior apex predator foraging ecology leopard seal stable isotope unmanned aerial systems |
description |
Describing the foraging dynamics of apex predators is crucial to understanding ecosystem function and to effective conservation and management. Leopard seals are conspicuous apex predators in Antarctic coastal ecosystems; however, their foraging ecology is poorly understood. Likely due to a geographical redistribution driven by pack-ice habitat reduction in the western Antarctic Peninsula, leopard seals have been hauling out at Cape Shirreff with increasing frequency in recent years. Utilizing that rare access we implemented an integrated sampling design including morphometrics, biological samples, and bio-logger deployments in January and February between 2008 and 2014. Subsequently, we quantified foraging behavior using: k-means cluster (diving), time-local convex hulls (movement), Bayesian stable isotope mixing models (diet), and linear regression (mass estimation) analyses. While they are typically described as generalist apex predators, video, dive, and movement data suggest they employ specialized foraging patterns. They affect coastal ecosystems through pathways beyond direct predation, including intraspecific kleptoparasitism, predator-induced stress effects, facultative scavenging and food caching. Leopard seal diving behavior is concentrated at night, is both shallow and coastal, and is composed of four distinct dive types. Haul-out probabilities were highest near midday and were positively correlated with available daylight. Video, scat and stable isotope analyses indicate that their summer diet contains four prey groups: Antarctic fur seals, pygoscelid penguins, krill, and demersal notothen fishes. Finally, measurements of body size and mass are fundamental to pinniped population management and research. The recent proliferation of unmanned aerial systems (UAS) in wildlife monitoring has provided a promising new platform for the photogrammetry of free-ranging pinnipeds. Photogrammetric measurements from a single, vertical image obtained using UAS were as accurate as ground measures, and provide a noninvasive approach for estimating the mass and body condition of pinnipeds. This dissertation provides substantial insight into the hunting tactics, foraging behavior, and diet of large adult female leopard seals and provides a viable option for future monitoring. |
format |
Doctoral or Postdoctoral Thesis |
author |
Krause, Douglas |
author_facet |
Krause, Douglas |
author_sort |
Krause, Douglas |
title |
The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula |
title_short |
The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula |
title_full |
The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula |
title_fullStr |
The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula |
title_full_unstemmed |
The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula |
title_sort |
foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (hydrurga leptonyx), at livingston island, antarctic peninsula |
publisher |
eScholarship, University of California |
publishDate |
2016 |
url |
http://www.escholarship.org/uc/item/7mp1s7bw http://n2t.net/ark:/13030/m5cz7vxj |
op_coverage |
216 |
long_lat |
ENVELOPE(-60.800,-60.800,-62.417,-62.417) ENVELOPE(-61.626,-61.626,-64.145,-64.145) ENVELOPE(-60.500,-60.500,-62.600,-62.600) ENVELOPE(-60.792,-60.792,-62.459,-62.459) |
geographic |
Antarctic Antarctic Peninsula Cape Shirreff Hydrurga Livingston Island Shirreff |
geographic_facet |
Antarctic Antarctic Peninsula Cape Shirreff Hydrurga Livingston Island Shirreff |
genre |
Antarc* Antarctic Antarctic Fur Seals Antarctic Peninsula Hydrurga leptonyx Leopard Seal Leopard Seals Livingston Island |
genre_facet |
Antarc* Antarctic Antarctic Fur Seals Antarctic Peninsula Hydrurga leptonyx Leopard Seal Leopard Seals Livingston Island |
op_source |
Krause, Douglas. (2016). The foraging ecology, diet, and mass estimation of an apex predator, the leopard seal (Hydrurga leptonyx), at Livingston Island, Antarctic Peninsula. UC San Diego: Oceanography. Retrieved from: http://www.escholarship.org/uc/item/7mp1s7bw |
op_relation |
http://www.escholarship.org/uc/item/7mp1s7bw qt7mp1s7bw http://n2t.net/ark:/13030/m5cz7vxj |
op_rights |
public |
_version_ |
1766264893308141568 |