Number Of Lions Research Articles

Climate variability, human wildlife conflict and population dynamics of lions Panthera leo

Large carnivores are threatened by habitat loss, declining prey populations and direct persecution. Pride dynamics of eight lion prides in the centre of the Etosha National Park, Namibia are described during a 16-year study. Since the beginning of the 1980s, the number of adult and subadult lions declined continuously to two third of its initial population size, and reached a new equilibrium in the 1990s. Pride sizes decreased from 6.3 adult females in 1989 to 2.8 lionesses in 1997. While the number of adult females declined continuously, the number of adult males, subadult females and subadult males remained constant over the years. A severe drought period, lasting for more than 20 years, led to declining prey populations inside the lions' territory. Besides declining prey populations, conflict with humans at the border of Etosha puts substantial pressure onto the lion population: 82% of all known lion mortalities were caused by humans, and most of these consisted of adult females (28%) and subadult males (29%). I postulate that the considerable decline in the lion population is a response to declining prey populations, and although the human predator conflict is severe, it does not seem to limit the size of Etosha's lion population.

Same size – same niche? Foraging niche separation between sympatric juvenile Galapagos sea lions and adult Galapagos fur seals

1. In vertebrates, patterns of resource utilization change throughout development according to age- and or size-specific abilities and requirements. Thus, interspecific competition affects different age classes differently. 2. Adults of sympatric species often show distinct foraging niche segregation, but juvenile resource use might overlap with adult competitors of similar body size. Resultant negative effects on juveniles can have important consequences for population dynamics, yet such interactions have received little attention in studies of mammalian communities. 3. Using GPS tracking devices, time-depth recorders and stable isotope data, we compared diving depth, activity time, trophic position and foraging habitat characteristics to investigate foraging niche overlap between similar-sized sympatric juvenile Galapagos sea lions (Zalophus wollebaeki) and adult Galapagos fur seals (Arctocephalus galapagoensis) and compared each group with much larger-bodied adult Galapagos sea lions. 4. We found little indication for direct competition but a complex pattern of foraging niche segregation: juvenile sea lions and adult fur seals dived to shallow depths at night, but foraged in different habitats with limited spatial overlap. Conversely, juvenile and adult sea lions employed different foraging patterns, but their foraging areas overlapped almost completely. 5. Consistency of foraging habitat characteristics between juvenile and adult sea lions suggests that avoidance of competition may be important in shaping foraging habitat utilization. Resultant specialization on a limited habitat could contribute to low sea lion numbers that contrast with high fur seal abundance. Our data suggest that exploitation by multiple predators within spatially restricted foraging ranges of juveniles might negatively impact juvenile foraging success and ultimately influence population dynamics.

California and Steller sea lion use of a major winter haulout in the Salish Sea over 45 years

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 467:253-262 (2012) - DOI: https://doi.org/10.3354/meps09911 California and Steller sea lion use of a major winter haulout in the Salish Sea over 45 years Timothy C. Edgell1,2, Mike W. Demarchi1,* 1LGL Limited environmental research associates, Sidney, British Columbia V8L 3Y8, Canada 2Present address: Stantec Consulting, Sidney, British Columbia V8L 5X4, Canada *Email: demarchi@lgl.com ABSTRACT: Populations of California sea lions Zalophus californianus and Steller sea lions Eumetopias jubatus in much of the eastern North Pacific Ocean have experienced significant growth since being protected in the early 1970s (by the US Marine Mammal Protection Act and Canada's Fisheries Act) from commercial harvests and fisheries-related culls. However, there remains substantial and unexplained variance in the annual number of sea lions using a major winter haulout at the entrance to the Salish Sea. We used linear regression on principal components to show maximum annual sea lion counts, adjusted for population growth, varied as a function of herring biomass and not local sea surface temperatures or precipitation. Results suggest that Race Rocks, British Columbia, Canada, is used as a stopover for an increasing number of sea lions approaching southern Vancouver Island to feed during the nonbreeding season. Reports of resource-driven movements of sea lions are not new, but this is the first study to use a multidecade data set to show resource-driven movements can underlie long-term patterns of population growth. Finally, we found an unexplained change in the seasonal use of Race Rocks affecting both species. Arrival at Race Rocks has occurred in late summer since 1965, but up to 1979 departure had occurred the following spring; since as late as 1997, departure has occurred mid winter. This study highlights the complexities of enacting conservation plans for species with latitudinal distributions and undergoing long-term population change. KEY WORDS: Pacific herring · Race Rocks · Sea surface temperature · Strait of Georgia · Pinniped · Juan de Fuca Strait · Vancouver Island Full text in pdf format PreviousNextCite this article as: Edgell TC, Demarchi MW (2012) California and Steller sea lion use of a major winter haulout in the Salish Sea over 45 years. Mar Ecol Prog Ser 467:253-262. https://doi.org/10.3354/meps09911 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 467. Online publication date: October 25, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

A genetically distinct lion (Panthera leo) population from Ethiopia

Lion (Panthera leo) numbers are in serious decline and two of only a handful of evolutionary significant units have already become extinct in the wild. However, there is continued debate about the genetic distinctiveness of different lion populations, a discussion delaying the initiation of conservation actions for endangered populations. Some lions from Ethiopia are phenotypically distinct from other extant lions in that the males possess an extensive dark mane. In this study, we investigated the microsatellite variation over ten loci in 15 lions from Addis Ababa Zoo in Ethiopia. A comparison with six wild lion populations identifies the Addis Ababa lions as being not only phenotypically but also genetically distinct from other lions. In addition, a comparison of the mitochondrial cytochrome b (CytB) gene sequence of these lions to sequences of wild lions of different origins supports the notion of their genetic uniqueness. Our examination of the genetic diversity of this captive lion population shows little effect of inbreeding. Immediate conservation actions, including a captive breeding programme designed to conserve genetic diversity and maintain the lineage, are urgently needed to preserve this unique lion population.

Top-down versus bottom-up forcing: evidence from mountain lions and mule deer

Abstract We studied mountain lions (Puma concolor) and mule deer (Odocoileus hemionus) inhabiting a Great Basin ecosystem in Round Valley, California, to make inferences concerning predator–prey dynamics. Our purpose was to evaluate the relative role of top-down and bottom-up forcing on mule deer in this multiple-predator, multiple-prey system. We identified a period of decline (by 83%) of mule deer (1984–1990), and then a period of slow but steady increase (1991–1998). For mule deer, bitterbrush (Purshia tridentata) in diets, per capita availability of bitterbrush, kidney fat indexes, fetal rates (young per adult female), fetal weights, and survivorship of adults and young indicated that the period of decline was typical of a deer population near or above the carrying capacity (K) of its environment. Numbers of mountain lions also declined, but with a long time lag. The period of increase was typified by deer displaying life-history characteristics of a population below K, yet the finite rate of growth (...

Estimating abundance of mountain lions from unstructured spatial sampling

AbstractMountain lions (Puma concolor) are often difficult to monitor because of their low capture probabilities, extensive movements, and large territories. Methods for estimating the abundance of this species are needed to assess population status, determine harvest levels, evaluate the impacts of management actions on populations, and derive conservation and management strategies. Traditional mark–recapture methods do not explicitly account for differences in individual capture probabilities due to the spatial distribution of individuals in relation to survey effort (or trap locations). However, recent advances in the analysis of capture–recapture data have produced methods estimating abundance and density of animals from spatially explicit capture–recapture data that account for heterogeneity in capture probabilities due to the spatial organization of individuals and traps. We adapt recently developed spatial capture–recapture models to estimate density and abundance of mountain lions in western Montana. Volunteers and state agency personnel collected mountain lion DNA samples in portions of the Blackfoot drainage (7,908 km2) in west‐central Montana using 2 methods: snow back‐tracking mountain lion tracks to collect hair samples and biopsy darting treed mountain lions to obtain tissue samples. Overall, we recorded 72 individual capture events, including captures both with and without tissue sample collection and hair samples resulting in the identification of 50 individual mountain lions (30 females, 19 males, and 1 unknown sex individual). We estimated lion densities from 8 models containing effects of distance, sex, and survey effort on detection probability. Our population density estimates ranged from a minimum of 3.7 mountain lions/100 km2(95% CI 2.3–5.7) under the distance only model (including only an effect of distance on detection probability) to 6.7 (95% CI 3.1–11.0) under the full model (including effects of distance, sex, survey effort, and distance × sex on detection probability). These numbers translate to a total estimate of 293 mountain lions (95% CI 182–451) to 529 (95% CI 245–870) within the Blackfoot drainage. Results from the distance model are similar to previous estimates of 3.6 mountain lions/100 km2for the study area; however, results from all other models indicated greater numbers of mountain lions. Our results indicate that unstructured spatial sampling combined with spatial capture–recapture analysis can be an effective method for estimating large carnivore densities. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Possible Relationships between the South African Captive-Bred Lion Hunting Industry and the Hunting and Conservation of Lions Elsewhere in Africa

The trophy hunting of lions is contentious due to increasing evidence of impacts on wild populations, and ethical concerns surrounding the hunting of captive-bred lions in South Africa. The captive-bred lion hunting industry in South Africa has grown rapidly while the number of wild lions hunted in other African countries has declined. In 2009 and 2010, 833 and 682 lion trophies were exported from South Africa, respectively, more than double the combined export (2009, 471; 2010, 318) from other African countries. There has been an associated increase in the prevalence of the export of lion bones from South Africa: at least 645 bones/sets of bones were exported in 2010, 75.0% of which went to Asia. Such trade could be problematic if it stimulated demand for bones from wild lions or other wild felids. Captive-bred lion hunting differs from wild lion hunting in that lions are hunted in smaller areas (49.9 ± 8.4 km 2 compared to 843 to 5933 km 2 , depending on the country), hunts are cheaper (US$20 000–40 000 compared to US$37 000–76 000 [excluding the costs of shooting other species and government charges]), shorter (3.3 compared to 14–21 days), success rates are higher (99.2% compared to 51.0–96.0%), and trophy quality is higher (skull length + breadth = 638.8 compared to 614–638 cm). Most clients perceive captive-bred and wild lion hunting to be different products but there is some overlap in markets: 48.7% of clients that had hunted captive-bred lions showed no preference regarding the type of future hunts. Owing to the size of the captive-bred hunting industry, even marginal overlap in demand could affect wild lion hunting significantly. If captive-bred lion hunting were ever prohibited, a transfer of demand to wild lion hunts could lead to elevated off-takes with negative impacts on wild populations. However, if off-takes of wild lions were held constant or reduced through effective regulation of quotas, increased demand could increase the price of wild lion hunts and strengthen financial incentives for lion conservation. These possibilities should be considered if future efforts are made to regulate captive-bred lion hunting.

Changes of population trends and mortality patterns in response to the reintroduction of large predators: The case study of African ungulates

Large predators have been reintroduced to an increasing number of protected areas in South Africa. However, the conditions allowing both prey and predator populations to be sustained in enclosed areas are still unclear as there is a lack of understanding of the consequences of such reintroductions for ungulate population dynamics. Variation in lion numbers, two decades after their first release, offered a special opportunity to test the effects of predation pressure on the population dynamics of seven ungulate species in the 960 km2 Hluhluwe-iMfolozi Park (HiP), South Africa. We used two different approaches to examine predator–prey relationships: the population response of ungulates to predation pressure after accounting for possible confounding factors, and the pattern of ungulate adult mortality observed from carcass records. Rainfall patterns affected observed mortalities of several ungulate species in HiP. Although lion predation accounted for most ungulate mortality, it still had no detectable influence on ungulate population trends and mortality patterns, with one possible exception. This evidence suggests that the lion population had not yet attained the maximum abundance potentially supported by their ungulate prey; but following recent increases in lion numbers it will probably occur soon. It remains uncertain whether a quasi-stable balance will be reached between prey and predator populations, or whether favoured prey species will be depressed towards levels potentially generating oscillatory dynamics in this complex large mammal assemblage. We specifically recommend a continuous monitoring of predator and prey populations in HiP since lions are likely to show more impacts on their prey species in the next years.

Minimum prey and area requirements of the Vulnerable cheetahAcinonyx jubatus: implications for reintroduction and management of the species in South Africa

AbstractIn South Africa there are efforts to manage reintroduced subpopulations of the Vulnerable cheetahAcinonyx jubatusin small reserves (10–1,000 km2) as a managed metapopulation. We estimated areas required to support cheetahs given varying prey densities, prey profiles and presence/absence of competing predators. A recent population and habitat viability assessment indicated that 20 subpopulations of 10 cheetahs or 10 subpopulations of 15 cheetahs are required to retain 90% of the heterozygosity of free-ranging cheetahs and to overcome stochastic events in the absence or presence of lionsPanthera leo, respectively. We estimate that 203 ± SE 42 km2(range 48–466 km2) is required to support 10 cheetahs in the absence of lions, whereas 703 ± SE 311 km2(166–2,806 km2) is required to support 15 cheetahs given equal numbers of lions, and 2,424 ± SE 890 km2(727–3,739 km2) given equal numbers of leopardsPanthera pardus, spotted hyaenasCrocuta crocuta, wild dogsLycaon pictusand lions. Existing subpopulations of cheetahs generally occur at densities higher than our mean predicted densities but usually within the range of predicted densities. The large area requirements of cheetahs have implications for the development of the managed metapopulation. Sourcing reintroduction sites of the sizes required to support recommended subpopulation sizes will be difficult. Consequently, innovative measures to increase the carrying capacity of reserves for cheetahs and/or to enlarge reserves will be required. Managers may be forced to stock cheetahs close to or beyond the carrying capacity of their reserves. Consequently, careful management of reintroduced subpopulations will be required to prevent declines in prey populations.

Genetic diversity, evolutionary history and implications for conservation of the lion (Panthera leo) in West and Central Africa

Aim In recent decades there has been a marked decline in the numbers of African lions (Panthera leo), especially in West Africa where the species is regionally endangered. Based on the climatological history of western Africa, we hypothesize that West and Central African lions have a unique evolutionary history, which is reflected by their genetic makeup. Location Sub-Saharan Africa and India, with special focus on West and Central Africa. Method In this study 126 samples, throughout the lion’s complete geographic range, were subjected to phylogenetic analyses. DNA sequences of a mitochondrial region, containing cytochrome b, tRNAPro, tRNAThr and the left part of the control region, were analysed. Results Bayesian, maximum likelihood and maximum parsimony analyses consistently showed a distinction between lions from West and Central Africa and lions from southern and East Africa. West and Central African lions are more closely related to Asiatic lions than to the southern and East African lions. This can be explained by a Pleistocene extinction and subsequent recolonization of West Africa from refugia in the Middle East. This is further supported by the fact that the West and Central African clade shows relatively little genetic diversity and is therefore thought to be an evolutionarily young clade. Main conclusions The taxonomic division between an African and an Asian subspecies does not fully reflect the overall genetic diversity within lions. In order to conserve genetic diversity within the species, genetically distinct lineages should be prioritized. Understanding the geographic pattern of genetic diversity is key to developing conservation strategies, both for in situ management and for breeding of captive stocks.

Population growth and colonization of Steller sea lions in the Glacier Bay region of southeastern Alaska: 1970s–2009

AbstractWe estimated trends in numbers of Steller sea lions in the Glacier Bay region of the eastern population from the 1970s to 2009. We documented the colonization of several new haul‐outs and the transition of one haul‐out (Graves Rocks) to a rookery, assessed seasonal patterns in distribution, and compared counts from different observation platforms. Sea lions increased in the region by 8.2%/yr (95%CI = 6.4%–10.0%), with the most growth at South Marble Island in Glacier Bay (16.6%/yr, 1991–2009) and rapid growth in Cross Sound. Seasonal patterns in the distribution of sea lions were likely influenced by new breeding opportunities and the seasonal availability of prey. Factors that likely contributed to the exceptional growth include availability of new habitat following deglaciation, immigration, redistribution, decreases in mortality, and ecosystem‐level changes. The rapid increase in sea lion numbers in this region is of particular interest in light of dramatic declines in the western population and evidence that Steller sea lions from both the eastern and western populations colonized the Graves Rocks rookery. The colonization and rookery development in this dynamic area may signal the reversal of the reproductive isolation of the two populations.

Genetic Analysis of Scats Reveals Minimum Number and Sex of Recently Documented Mountain Lions

Abstract Recent records of mountain lions Puma concolor and concurrent declines in desert bighorn sheep Ovis canadensis mexicana on Kofa National Wildlife Refuge in Arizona, United States, have prompted investigations to estimate the number of mountain lions occurring there. We performed noninvasive genetic analyses and identified species, individuals, and sex from scat samples collected from the Kofa and Castle Dome Mountains. From 105 scats collected, we identified a minimum of 11 individual mountain lions. These individuals consisted of six males, two females and three of unknown sex. Three of the 11 mountain lions were identified multiple times over the study period. These estimates supplement previously recorded information on mountain lions in an area where they were historically considered only transient. We demonstrate that noninvasive genetic techniques, especially when used in conjunction with camera-trap and radiocollaring methods, can provide additional and reliable information to wildlife managers, particularly on secretive species like the mountain lion.

Review: KAYWA and Kooaba

KAYWA ; www.kaywa.com Kooaba ; www.kooaba.com If architecture is a kind of hardware, it may seem surprising that in recent months these pages have been filled, at least in part, with reviews of software. In particular, those programs and institutions that offer graphic interface-based models of space (e.g., Google Earth, ARTstor, etc.) have rightfully received attention as current or potential tools of the art and architectural historian. These reviews have offered insights into the ways in which our discipline is changing——augmented and perhaps impoverished——by the inevitable onrush of these technologies. However, a crucial aspect of all of these programs or tools, which has been consistently elided (and architectural historians are by no means alone in perpetrating this elision), is their primary status as advertising. If this claim strikes the reader as strange, a quick visual analysis of any Google site, ARTstor metadata page, or Twitter feed should set you at an appropriate level of unease. To the serious historian of art and architecture, advertising is something of a beete noire. To caricature the debate, there remains a profound tension between those in our disciplines who, on the one hand, would prefer to exclude advertising from the realm of true art, and on the other, those who would expand the disciplines' boundaries to include advertising, folk art, propaganda, institutional ephemera, industrial or commercial illustration, commodities, and so on, within a revised canon of visual culture.1 This debate has concealed from most historians of art and architecture the technical, aesthetic, and spatial aspects of advertising, and forestalled the serious study and critique that only our disciplines are prepared to provide. The advertising image acts as an index. Its primary function is to point away from itself, and in its most effective forms, it actually redirects our attention to from the image to the referent. Yet the advertising …

The Minoan lion: presence and absence on Bronze Age Crete

Animal depictions are frequently treated by archaeologists either as direct reflections of human-animal relations or as symbolic of social realities. This paper offers a different way of conceptualizing animal depictions, as objects which mediate between society and human relationships with non-human animals. The focus here is on the large number of lions depicted on sealstones from Bronze Age Crete, despite there being no evidence (excluding the depictions themselves) that lions were present on Crete during this period. This paper examines how these depictions change over the course of the Bronze Age, and suggests links between iconographic features and knowledge of, and encounters with, real lions. It considers the interplay between the affordances of lions revealed in the depictions, as dangerous predators, and the affordances of the objects, as a means of social interaction. The Minoan lion is an animal which is neither reducible to its iconographic manifestations nor possible to understand apart from a network of material culture.

Estimating lion population variables: prey and disease effects in Kruger National Park, South Africa

Context. Lion (Panthera leo Linnaeus, 1758) populations experience a range of ecological and human influences that affect their demography. Few lion populations have reliable estimates of population size, trends in these, or demographic profiles. Threats such as those imposed by diseases are thus hard to evaluate and respond to. Aims. To calibrate call-up stations and define survey effort required to achieve estimates with known precision, and extract age structures and estimate survival rates, to estimate lion numbers, sex and age structure and survival rates, and then to evaluate the effect of bovine tuberculosis (bTB) on estimates of lion density and survival. Methods.By using call-up stations, we developed a statistically robust approach to estimate selected population variables and evaluated the perceived threat of bTB in landscapes of varying prey biomass in the Kruger National Park. Key results. The size of the lion population was stable, although long intervals between present and historical estimates limit this conclusion. Density and survival rates associated positively with prey biomass, and a positive association was detected between the survival rate and bTB prevalence, with survival being higher in areas that had high prevalence of bTB. Male survival was lower than female survival, disregarding the effects of prey biomass or bTB prevalence. Body condition of lions was high, with scores lower at low to medium prey density. Conclusions. The effect of an exotic disease on the Kruger lion population may be negligible at present. Intra-specific competition in areas where lions live at high densities affects survival rate. However, droughts could disrupt the hierarchical influences of prey biomass and bTB prevalence on lion densities and survival. Implications. To evaluate the effect of an exotic disease on lion demography, population surveys should include age- and sex-structure assessments, complemented with focal studies of fecundity. This reflects the importance of understanding host–disease dynamics to inform management options.

Status of the Porcupine (Erithizon dorsatuh) in Arizona, 2000–2007

Concern over an apparent paucity of recent porcupine (Erithizon dorsatum) observations in Arizona, prompted us to replicate Walter P. Taylor's (1935) letter requesting information from U. S. Forest Service and other government agency field personnel on the animal's status. On the basis of 162 reports of >314 porcupine observations we concluded that porcupines are thinly and unevenly distributed throughout the state with animals reliably sighted in select habitats near prairie dog towns, in certain suburban settings, and on the North Kaibab Plateau. We attribute this general scarcity to predation by mountain lions (Puma concolor) and possibly black bears (Ursus americanus), and agree with Taylor that predator control efforts resulting is a depressed lion population is the most likely explanation for the high number of porcupines reported during the 1924–1934 period. Although the porcupine does not appear to be endangered, there is no evidence to suggest that lion numbers are decreasing and that porcupine numbers may again increase. Prédation, and perhaps increased mortality from night-time road kills, has made porcupines an unusual animal in most of Arizona.

Identifying a potential lion Panthera leo stronghold in Queen Elizabeth National Park, Uganda, and Parc National des Virunga, Democratic Republic of Congo

Conservationists are raising concerns over high lion Panthera leo mortality and prey population declines in the area at the frontier between the Democratic Republic of Congo and Uganda. Confirming if threats to lions are severe or lion populations are disappearing requires ex- tensive surveys on the ground because aerial detection of lions is inaccurate. Yet, ground surveys over large areas are unsafe or infeasible in the war-torn study area. We used aerial surveys of medium- to large-bodied ungulate prey to estimate lion abundance in two adjoining parks: Queen Elizabeth National Park, Uganda, and Parc National des Virunga, Democratic Republic of Congo. We validated two approaches to predict lion abundance using total counts of lions from Uganda. From this, we predict the two national parks together could have held 221 lions in 2004 and they have the potential to hold 905 lions if prey recover and lion-specific mortality is curbed. This makes the region a potential stronghold for the species in central Africa. How- ever, a recent one third decline in lion numbers in the Ugandan Park and pervasive threats to the Congolese Park lead us to recommend immediate conservation interven- tion for lions and their prey. In Uganda, we recommend focused action to protect lions from poaching and re- taliation, whereas in Congo, general enforcement of wildlife protection and a ground-based survey for lions are needed.

Natural and anthropogenic factors associated with the distribution of South American sea lion along the Atlantic coast

The aim of this work was to analyse those characteristics of the Atlantic coast that are associated with distribution, abundance and breeding activity of Otaria flavescens at three ecological scales. We followed a research strategy that consists in looking at the variables that are associated with the pattern of distribution at regional and landscape scales, instead of following local population in time. We used bibliographic data of censuses carried out between 1946 and 1997 and a Geographic Information System (GIS) to integrate information proceeding from censuses and different environmental variables. At a regional scale, we found that the distribution of breeding colonies did not vary in the period of time analysed and was associated with the pattern of occupation of the coast and the tide width. There was a significant decrease in abundance between 1946 and 1997. In ‘north-central Patagonia’, the segment of coast with the highest number of sea lions in Argentina, distribution of colonies was associated with islands availability and negatively correlated with places were anthropogenic disturbance was high. At a local scale, breeding colonies were positive associated with slight slope coasts and negatively associated to rocky beaches. We identify those characteristics of the coast associated with distribution of breeding colonies of O. flavescens, which operate at different ecological and temporal scales.

Demographic independence along ecosystem boundaries in Steller sea lions revealed by mtDNA analysis: implications for management of an endangered species

Previous genetic studies indicate Steller sea lions ( Eumetopias jubatus (Schreber, 1776)) comprise three phylogeographically distinct populations. However, differences in population trends and ecology and the limited extent of recorded dispersal suggest structure may be present at smaller scales. We examined sequence variation within a longer segment (531 bp) of the mtDNA control region in greater numbers (n = 1654) of sea lions from across Alaska than earlier investigations to investigate fine-scale dispersal patterns in Steller sea lions. We detected high levels of haplotypic diversity (h = 0.934) and confirmed phylogeographic differentiation between southeastern and western Alaska (Φst= 0.23, P < 0.0001), but also found significant differentiation at regional and local scales. Rookeries in the Gulf of Alaska, eastern Bering Sea, and eastern Aleutians were distinct from rookeries in the central and western Aleutians (Fst= 0.021, P < 0.0001; Φst= 0.017, P < 0.0001). The location of this split coincides with an oceanographic divergence between continental shelf and ocean basin waters and with differences in sea lion foraging ecology and population trends. A number of rookeries were also significantly differentiated from nearby rookeries (Fst= 0.02–0.025, P < 0.05), signifying substantial female-mediated philopatry, in some cases, at local scales. These findings have important implications for understanding the ecology of Steller sea lions in relation to marine ecosystems and the causes of population declines, and they provide guidance for management, including the identification of management stocks.

Seasonal availability of abundant, energy-rich prey influences the abundance and diet of a marine predator, the Steller sea lion Eumetopias jubatus

Steller sea lions Eumetopias jubatus are central-place foragers that forage in the marine environment while using terrestrial sites to rest and care for young. Some terrestrial sites are used seasonally; however, the reasons for doing so are not fully understood. We addressed the hypothesis that seasonal availability of prey influences seasonal abundance and diet of sea lions. We quantified monthly prey availability and sea lion abundance and quarterly diet composition at Benjamin Island in SE Alaska (2001-2004). Large numbers of sea lions occupied Benjamin Island during the non- breeding season from October to April when Pacific herring Clupea pallasii biomass was highest. Herring was the most common species in sea lion diet (frequency of occurrence (FO) = 90%) and comprised over 81% of the available pelagic prey biomass and 96% of the energy encountered dur- ing pelagic surveys. Walleye pollock Theragra chalcogramma accounted for 19% of the available prey biomass but was only slightly less common in sea lion diet (FO = 88%) than herring. Herring bio- mass was correlated with the number of sea lions; in contrast, there was no relationship between pol- lock biomass and number of sea lions. Several fish species were found in nearshore areas, but were uncommon in sea lion diet. Sea lions consumed the available pelagic prey but little of the available nearshore prey. The FO of herring and pollock in sea lion diet did not differ significantly between seasons; however, the FO of other seasonal prey species differed between seasons. Seasonal occupa- tion of Benjamin Island by sea lions is influenced by seasonally available, densely aggregated, energy-rich prey.