Otago Peninsula Research Articles

Straight Line Foraging in Yellow-Eyed Penguins: New Insights into Cascading Fisheries Effects and Orientation Capabilities of Marine Predators

Free-ranging marine predators rarely search for prey along straight lines because dynamic ocean processes usually require complex search strategies. If linear movement patterns occur they are usually associated with travelling events or migratory behaviour. However, recent fine scale tracking of flying seabirds has revealed straight-line movements while birds followed fishing vessels. Unlike flying seabirds, penguins are not known to target and follow fishing vessels. Yet yellow-eyed penguins from New Zealand often exhibit directed movement patterns while searching for prey at the seafloor, a behaviour that seems to contradict common movement ecology theories. While deploying GPS dive loggers on yellow-eyed penguins from the Otago Peninsula we found that the birds frequently followed straight lines for several kilometres with little horizontal deviation. In several cases individuals swam up and down the same line, while some of the lines were followed by more than one individual. Using a remote operated vehicle (ROV) we found a highly visible furrow on the seafloor most likely caused by an otter board of a demersal fish trawl, which ran in a straight line exactly matching the trajectory of a recent line identified from penguin tracks. We noted high abundances of benthic scavengers associated with fisheries-related bottom disturbance. While our data demonstrate the acute way-finding capabilities of benthic foraging yellow-eyed penguins, they also highlight how hidden cascading effects of coastal fisheries may alter behaviour and potentially even population dynamics of marine predators, an often overlooked fact in the examination of fisheries’ impacts.

Identifying eradication units in an invasive mammalian pest species

Eradication of invasive species is an important component for species conservation and ecosystem restoration. Success of eradications is dependent on knowledge of population connectivity in order to determine reinvasion pathways, and hence populations requiring simultaneous eradication (eradication units). The common brushtail possum (Trichosurus vulpecula) was introduced into New Zealand from Australia and Tasmania, and now occupies a wide range of habitats across the majority of New Zealand. Possums are one of the most destructive invaders within New Zealand, with extensive control operations occurring throughout the country. Understanding the population connectivity of possums on mainland New Zealand (North and South Islands) will enhance the success of planned eradications. We examined the genetic population structure of invasive possums to identify gene flow, thus reinvasion pathways, between seven populations around Dunedin and on the Otago Peninsula where eradication of possums is occurring. Genetic variation at 12 microsatellite loci was comparable between all sampled populations and exhibited a significant isolation by distance pattern. Bayesian clustering methods supported the existence of two population clusters, indicating the presence of a reinvasion pathway onto the Otago Peninsula from urban areas at the Southern end of the Peninsula. To avoid recolonisation, all possums on the Otago Peninsula should be eradicated simultaneously, with the implementation and ongoing maintenance and monitoring of an urban buffer zone. We recommend pre-eradication genetic analyses be adopted by all pest managers to define appropriate eradication units, thereby maximising eradication success and avoiding costly failures.

Importance of studying foraging site fidelity for spatial conservation measures in a mobile predator

The efficiency of spatial conservation measures for threatened species depends mostly on the proportion of time that animals spend within the protected areas. We illustrate this with our case study of the population of recolonizing female New Zealand (NZ) sea lions Phocarctos hookeri (n = 13) at Otago Peninsula, South Island, NZ. Human interactions at sea, where sea lions forage, are of concern, and spatial management measures have been proposed. Understanding the level of foraging site fidelity of these animals was consequently essential. We used satellite tracking of individuals across three autumns to assess foraging site fidelity and year-round on-land sighting surveys over 2.5 years as proxy to foraging areas outside autumns. Each individual exhibited a high level of autumnal site fidelity for foraging areas between years (64% overlap between 65% Kernel ranges with a 3-km buffer) while using beaches along a 12-km stretch of coastline during 96 ± 8% (range 79–100%) of their time onshore. As a proxy for foraging areas outside autumns, these animals exhibited a high level of site fidelity to this stretch of coastline throughout the year. Breeding females were sighted there during 86% of months (range = 73–100%) and non-breeding females during 69% of months (range = 58–90%). The site fidelity of these animals indicates that protected areas would be efficient in this case and highlights the importance of studying foraging site fidelity in mobile predators to design efficient conservation measures.

Foraging Behaviour of Juvenile Female New Zealand Sea Lions (Phocarctos hookeri) in Contrasting Environments

Foragers can show adaptive responses to changes within their environment through morphological and behavioural plasticity. We investigated the plasticity in body size, at sea movements and diving behaviour of juvenile female New Zealand (NZ) sea lions (Phocarctos hookeri) in two contrasting environments. The NZ sea lion is one of the rarest pinnipeds in the world. Most of the species is based at the subantarctic Auckland Islands (AI; considered to be marginal foraging habitat), with a recolonizing population on the Otago Peninsula, NZ mainland (considered to be more optimal habitat). We investigated how juvenile NZ sea lions adjust their foraging behaviour in contrasting environments by deploying satellite-linked platform transmitting terminals (PTTs) and time-depth recorders (TDRs) on 2–3 year-old females at AI (2007–2010) and Otago (2009–2010). Juvenile female NZ sea lions exhibited plasticity in body size and behaviour. Otago juveniles were significantly heavier than AI juveniles. Linear mixed effects models showed that study site had the most important effect on foraging behaviour, while mass and age had little influence. AI juveniles spent more time at sea, foraged over larger areas, and dove deeper and longer than Otago juveniles. It is difficult to attribute a specific cause to the observed contrasts in foraging behaviour because these differences may be driven by disparities in habitat/prey characteristics, conspecific density levels or interseasonal variation. Nevertheless, the smaller size and increased foraging effort of AI juveniles, combined with the lower productivity in this region, support the hypothesis that AI are less optimal habitat than Otago. It is more difficult for juveniles to forage in suboptimal habitats given their restricted foraging ability and lower tolerance for food limitation compared to adults. Thus, effective management measures should consider the impacts of low resource environments, along with changes that can alter food availability such as potential resource competition with fisheries.

Direct and Indirect Effects of Grazing by Introduced Mammals on a Native, Arboreal Gecko (Naultinus gemmeus)

We examined relationships between livestock grazing and the activity of introduced rodents and population density of Jewelled Geckos, Naultinus gemmeus (Diplodactylidae) on the Otago Peninsula, South Island, New Zealand. We expected livestock grazing to prevent the proliferation of rank grass (which is often associated with high rodent densities) and thereby reduce the frequency of predation by rodents on Jewelled Geckos. Thus, we predicted activity of rodents to be lower, and density of Jewelled Geckos higher, at sites grazed by livestock. We tested this for two habitats: Coprosma spp. shrubland and regenerating kānuka (Kunzea ericoides) forest. We quantified density of Jewelled Geckos using visual searches, photography and mark–recapture (POPAN formulation). We used tracking tunnel surveys to estimate the activity of introduced rodents. The activity of rodents (Rattus spp. and Mus musculus) was significantly higher at ungrazed compared to grazed sites in both habitats. Density of Jewelled Geckos in Coprosma was over four times higher at grazed sites and decreased with increasing rodent activity; however, in kānuka, we found a contrasting result with density being significantly higher at the ungrazed sites. We infer that in ungrazed Coprosma, rank grasses support high rodent densities and, consequently, high predation of Jewelled Geckos. Thus, grazing by introduced livestock may promote the survival of Jewelled Geckos and the persistence of high density populations in Coprosma shrubland. In contrast, grazing in regenerating kānuka may impact on Jewelled Geckos negatively, possibly by removing thermal refugia.

Autumn diet of recolonising female New Zealand sea lions based at Otago Peninsula, South Island, New Zealand

New Zealand (NZ) sea lions (Phocarctos hookeri) are slowly recolonising the Otago coast, South Island, New Zealand. The increase in their numbers may lead to resource competition with other marine predators and fisheries. We determined the diet of female NZ sea lions at Otago during autumn. In total, 571 scats and 110 regurgitations were collected on Otago Peninsula during 2008 and 2009. Barracouta (Thyrsites atun) and jack mackerel (Trachurus sp.) were the two main prey species and accounted for 26% and 31% of the reconstituted biomass, respectively. This was consistent between two years. Only five other species contributed > 5% of the diet by biomass in either year. Prey species are all found on the narrow continental shelf surrounding Otago Peninsula. The main prey species of Otago NZ sea lions may be of higher energy content than prey in the Auckland Islands (remnant breeding area). Resource overlap with other marine predators and fisheries appears to occur around Otago Peninsula. A marine trophic model of the area off Otago Peninsula would help understanding potential competition between marine predators and fisheries in this area.

In the shallow end: diving behaviour of recolonising female New Zealand sea lions (Phocarctos hookeri) around the Otago Peninsula

Female New Zealand sea lions ( Phocarctos hookeri (Gray, 1844)) at the Auckland Islands (remnant populations) are the deepest and longest diving otariids. These remnant populations are found at the margin of the historical range of the species. We hypothesized that diving behaviours of animals in the core of their historical range is less extreme owing to a better marine habitat. All female New Zealand sea lions (n = 13, aged 2–14 years) born on the Otago Peninsula (initial recolonising population) were equipped with time–depth recorders during April and May 2008, 2009, and 2010. The mean dive depth was 20.2 ± 24.5 m and mean dive duration was 1.8 ± 1.1 min, some of the lowest values reported for otariids. Otago female New Zealand sea lions did not exhibit two distinct diving specialisations as reported at the Auckland Islands. Otago adult females exceeded calculated aerobic dive limits in 7.1% of dives compared with 68.7% at the Auckland Islands. The contrasting differences in diving behaviour between Otago and the Auckland Islands suggest that Otago represents a better marine habitat for New Zealand sea lions, with food easily accessible to animals of all ages.

New species of Hyalidae (Crustacea, Peracarida, Amphipoda) from New Zealand waters

Two new species of hyalid amphipods are described from New Zealand waters. Apohyale papanuiensis sp. nov. is described from Little Papanui on the Otago Peninsula, and New Zealand records of Apohyale media are placed in its synonymy. Apohyale freemenae sp. nov. is recorded from the Antipodes Islands of the New Zealand subantarctic. A key to the New Zealand species of Apohyale is provided.

Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations

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 432:247-256 (2011) - DOI: https://doi.org/10.3354/meps09176 Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations A. A. Augé1,*, B. L. Chilvers2, A. B. Moore3, L. S. Davis1 1Zoology Department, and 3School of Surveying, University of Otago, Dunedin 9016, New Zealand 2Aquatic and Threats Unit, Department of Conservation, Wellington 6011, New Zealand *Email: amelie.auge@gmail.com ABSTRACT: The New Zealand sea lion Phocarctos hookeri historically bred on the New Zealand mainland (South and North Islands). Subsistence hunting and later commercial sealing reduced its distribution to 3 breeding areas at the spatial edges of its historical distribution range, in the Auckland Islands (AI) and on Campbell Island. Here, we present foraging areas and foraging trips of female New Zealand sea lions from the Otago Peninsula, where a recolonising population has been found in the core of the historical range of the species. We compare the results with data from the AI in order to assess the theory that the spatial margin of a species’ distribution represents the lower end of habitat suitability. Female New Zealand sea lions at Otago had significantly smaller foraging ranges than females at the AI (mean 65% Kernel ranges: 47 ± 25 km2 versus 687 ± 109 km2), made shorter foraging trips (mean 11.8 ± 2.3 h versus 66.2 ± 4.2 h), and spent 40% less time at sea overall. Juvenile females at Otago from age 2 onwards could access foraging grounds used by adult females nursing pups; this is unlikely to be the case at the AI due to the large distances and associated depths of foraging grounds. Our study illustrates the theory that spatial marginality is related to habitat marginality. Existing management measures to mitigate the impact of bycatch in fisheries on declining remnant colonies around the AI were modelled based on populations exploiting optimal habitat. They should now integrate this new information. KEY WORDS: Phocarctos hookeri · Pinnipeds · Spatial · Marginal · Satellite tracking · Marine ­conservation Full text in pdf format PreviousNextCite this article as: Augé AA, Chilvers BL, Moore AB, Davis LS (2011) Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations. Mar Ecol Prog Ser 432:247-256. https://doi.org/10.3354/meps09176 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 432. Online publication date: June 27, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Detection of hydroxamate siderophores in coastal and Sub-Antarctic waters off the South Eastern Coast of New Zealand

In this study, we report siderophore-type compounds found in coastal and Sub-Antarctic waters within a 60 km transect off the south east coast of Otago Peninsula in New Zealand. The presence of siderophore activity was detected using chrome azurol S assay (CAS) from organic compounds extracted from ~ 200 to 480 L seawater by pre-concentration on XAD-16 resin. Csaky and Rioux assays indicated the presence of more than one functional type of siderophore or siderophore-like compound. Strong Fe-binding ligand (L 1) concentrations, the sum of ligands (ΣL), and their stability constants were measured from ambient seawater samples using competing ligand equilibration-cathodic stripping voltammetry (CLE-CSV). In the study area L 1 ranged from 0.23 to 0.69 nM (logK′ FeL1,Fe3+ = 22.0–22.8), whereas ΣL values ranged from 0.53 to 1.23 nM (logK′ FeΣL,Fe3+ = 21.4–22.2). Dissolved Fe (DFe) concentrations were measured by CSV and ranged from 0.22 to 0.45 nM. This is the first application of a new liquid chromatography–tandem mass spectrometry method using the natural iron-isotope pattern to characterize siderophore-type compounds isolated from natural seawater. Altogether six siderophore-type compounds with hydroxamate functionality were detected in one coastal, as well as Sub-Antartic surface and subsurface samples. This new method and the derived results provide a foundation for future investigations of sources and structures of strong ligands in the Southern Ocean and elsewhere.

Prevalence of Leucocytozoon spp, in the endangered yellow-eyed penguin Megadyptes antipodes

Yellow-eyed penguins on Stewart Island were identified with a Leucocytozoon spp. of a novel lineage in association with a high regional incidence of chick mortality (n=32, 100% mortality) during the November 2006 to January 2007 breeding season. Fourteen chicks from Stewart Island were examined post-mortem and histologically for Leucocytozoon infection. In addition, a survey of blood to detect Leucocytozoon spp. infections using PCR was performed on 107 yellow-eyed penguins from 4 distinct nesting areas on the South Island (Oamaru, Otago Peninsula, and Catlins) (n=95), and Stewart Island (n=12). The results of the study revealed that 2 of the 14 (14%) chicks necropsied showed severe, disseminated megaloschizont formation in the liver, spleen, lung, kidney and other tissues characteristic of leucocytozoonosis. Eighty-three percent (83%) of blood samples collected from Stewart Island penguins contained Leucocytozoon DNA, whereas samples from the 3 other nesting areas were negative for the blood parasite. Leucocytozoon spp. DNA sequences isolated from blood and tissues of adults (n=10) and chicks (n=7) were similar and grouped with other published Leucocytozoon spp. sequences but in a distinct cluster together with closely related isolates from a Western march harrier (Circus aerginosus) and common loon (Gavia immer). These findings suggest that yellow-eyed penguins on Stewart Island are infected with a regionally isolated, host-specific Leucocytozoon spp. which may contribute to the high chick mortality observed during this period.

A new species of Ixodiphagus (Hymenoptera: Chalcidoidea: Encyrtidae) parasitizing seabird ticks in New Zealand

Ixodiphagus taiaroaensis n. sp., is described and illustrated from specimens of Encyrtidae that emerged from nymphs of Ixodes uriae White, 1852 and I. eudyptidis Maskell, 1885 (Acari: Ixodidae) collected on the Otago Peninsula, New Zealand. The findings represent the first record of a tick parasitoid in New Zealand as well as the first recorded instance worldwide of parasitism in the host tick species. Aspects of the biology and possible origins of the new species are discussed.

Cat-exclusion zones in rural and urban-fringe landscapes: how large would they have to be?

Context. The process of urban sprawl brings the human population and their domestic cats (Felis catus) in close contact with wildlife in areas that were previously remote, including reserves and conservation areas created to protect populations of vulnerable or threatened species. Various mitigation measures have been proposed, including devices designed to hinder cat hunting ability, desexing to reduce wandering and nuisance behaviours, containment at night or at all times and regulations governing cat ownership. Such regulations may aim to reduce cat densities by limiting the number of cats per household, or they may define zones around sensitive conservation areas where cat ownership is prohibited. Aims. The present study sought to establish the necessary size of cat-exclusion zones in rural and urban-fringe landscapes where vulnerable prey species may also reside. Methods. With GPS collars, we tracked 38 domestic cats at three sites (one rural, two urban fringe) where small reserves contained threatened lizard species. Key results. Home ranges (95% kernel density estimates) were considerably larger for cats at the rural site (0.3–69 ha) than at urban-fringe sites (0.35–19 ha at Kaitorete Spit and 0.2–9 ha at Otago Peninsula), and were larger at night than day. Resource selection ratios indicated avoidance of open areas with little cover, such as cultivated areas (farmland), tussock grassland and duneland, whereas sources of cover such as trees and buildings were preferred. Maximum distances moved and large variability between individual cats suggest buffers in rural landscapes would need to be at least 2.4 km wide, whereas those in urban-fringe habitat could be half as large. Conclusions. Despite significant home-range size differences exhibited by cats living in rural v. urban-fringe habitats, exclusion zones would need to be wide to account for considerable inter-cat variation in movement behaviour. Implications. The size of an effective cat-exclusion zone should represent the specific landscape, amount of residential development and substantial variability between individual cats.

Cryptic species complexes in manipulative echinostomatid trematodes: when two become six

Recent studies have shown that some digenean trematodes previously identified as single species due to the lack of distinguishing morphological characteristics actually consist of a number of genetically distinct cryptic species. We obtained mitochondrial 16S and nuclear ITS1 sequences for the redial stages of Acanthoparyphium sp. and Curtuteria australis collected from snails and whelks at various locations around Otago Peninsula, New Zealand. These two echinostomes are well-known host manipulators whose impact extends to the entire intertidal community. Using phylogenetic analyses, we found that Acanthoparyphium sp. is actually composed of at least 4 genetically distinct species, and that a cryptic species of Curtuteria occurs in addition to C. australis. Molecular data obtained for metacercariae dissected from cockle second intermediate hosts matched sequences obtained for Acanthoparyphium sp. A and C. australis rediae, respectively, but no other species. The various cryptic species of both Acanthoparyphium and Curtuteria also showed an extremely localized pattern of distribution: some species were either absent or very rare in Otago Harbour, but reached far higher prevalence in nearby sheltered inlets. This small-scale spatial segregation is unexpected as shorebird definitive hosts can disperse trematode eggs across wide geographical areas, which should result in a homogeneous mixing of the species on small geographical scales. Possible explanations for this spatial segregation of the species include sampling artefacts, local adaptation by first intermediate hosts, environmental conditions, and site fidelity of the definitive hosts.

New Zealand sea lion, Phocarctos hookeri, pup production—1995 to 2006

The New Zealand sea lion (NZ sea lion), Phocarctos hookeri, is New Zealand's only endemic pinniped. Classified as vulnerable, it is one of the world's rarest pinnipeds. During the 1994/95 austral summer, a long‐term population‐monitoring programme of the Auckland Island colonies was initiated using standard procedures to estimate annual pup production. This paper reports the pup production estimates for the known NZ sea lion population over the last 12 years (1994/95 to 2005/06), and the variation in pup production estimates for the Auckland Islands. sixty‐four percent of the pup production for the entire NZ sea lion population occurred at Dundas Island, followed by Enderby Island (19%), and Figure of Eight Island (3%). These three sites are all at the Auckland Islands, making this area the primary breeding site for this species with 86% of all pup production occurring here. The remaining 14% were born at Campbell Island, with otago Peninsula representing <0.1%. The pup production estimates for the NZ sea lion population varied considerably by year and breeding area. The most significant change recorded was at the primary breeding site for this species, the Auckland Islands, which had a 31% decline in pup production between 1997/98 and 2005/06 owing to a combination of disease events and incidental by‐catch from commercial fishing activity.

Tides in two constricted New Zealand lagoons

We used a non‐linear model, which incorporates tidal choking coupled to the geometry of the lagoon and its channel to interpret data collected from two constricted New Zealand lagoons, Hooper's Inlet and Papanui Inlet, Otago Peninsula, south eastern New Zealand. The model reproduced many of the observed features, although it yielded better results for Papanui Inlet which had weaker tidal choking. Tide data from both lagoons showed varying degrees of distortion owing to the constricted channels. Both lagoons were characterised by a reduced amplitude and a lag in the timing of high and low tides compared to the open sea reference point at Taiaroa Head, with an irregular ebb‐flood duration. Although Taiaroa Head had a mean tidal range of 1.49 m and its high and low tides occurred first, Papanui Inlet had a tidal range of 1.15m and lagged Taiaroa Head by 60 min, whereas adjacent Hooper's Inlet had the smallest range of 0.43m and a lag of 103 min. All sites had a clear spring‐neap envelope, with Hooper's Inlet lagging behind Taiaroa Head and Papanui Inlet by about 1 day. The reduced amplitude and the lag in timing of high and low tides compared to the forcing open sea tide are caused by tidal choking owing to the narrow, shallow channels connecting the lagoons to the open sea.

Predation by New Zealand sea lions ( Phocarctos hookeri) as a threat to the viability of yellow-eyed penguins ( Megadyptes antipodes) at Otago Peninsula, New Zealand

This study presented evidence that creates a quandary for conservation management: predation by one threatened species, New Zealand sea lion ( Phocarctos hookeri), threatens the viability of another threatened species, yellow-eyed penguin ( Megadyptes antipodes), at Otago Peninsula, South Island, New Zealand. Otago Peninsula holds the largest population of yellow-eyed penguins on South Island and the only breeding population of New Zealand sea lions on the New Zealand mainland. New Zealand sea lions here represent the vanguard of re-colonisation within their prehistoric range, with nine females and 50–70 males resident in 2005. The initial indication of a potential problem was an attack on a yellow-eyed penguin by a New Zealand sea lion witnessed in 1996. The majority of 20 records for attacks were at two neighbouring sites, where they coincided with decreases in penguin nest numbers and adult annual survival. In contrast, penguin nest numbers increased at a third site, the main base for male sea lions at Otago Peninsula. Evidence from prey remains indicated that male sea lions did not eat yellow-eyed penguins but that females ate 20–30 annually, with one individual possibly responsible for most kills. Modelling indicated that the penguin population at any one site could not remain viable if it was the sole source of penguins killed. The dilemma is either to do nothing, and risk collapse of the Otago Peninsula population of yellow-eyed penguins, or to take action against known culprits, and risk failure in re-colonisation of the New Zealand mainland by New Zealand sea lions.

Gnathostomulida from the Otago Peninsula, southern New Zealand

Gnathostomulida from the Otago Peninsula, southern New Zealand

Gnathostomulida from the Otago Peninsula, southern New Zealand

Ten species of Gnathostomulida, three new to science, are reported from the SE end of South Island, New Zealand: Haplognathia asymmetrica, H. gubbarnorum, H. rosea, H. ruberrima, Pterognathia sica, P. ugera, P. tuatara n. sp., P. portobello n. sp., Gnathostomula cf. salotae and Austrognatharia australis n. sp. This paper brings the number of species known from New Zealand to 12, of species known from the Pacific Ocean to 43, and of described gnathostomulid species worldwide to 98.

BEHAVIORAL THERMOREGULATION OF THE NEW ZEALAND SEA LION (PHOCARCTOS HOOKERI)

AbstractBehavioral thermoregulation of New Zealand sea lions (Phocarctos hookeri) was studied at a male haul‐out ground at Papanui Beach, Otago Peninsula, New Zealand. The proportion of time spent by sea lions in each of five postures (prone, curled, oblique, ventral‐up, dorsal‐up) and also with the number of flippers exposed or tucked (hind and fore) at different black‐bulb temperature (Tbb°C) ranges was recorded. Use of prone and curled postures (0–1 flippers exposed) declined as Tbb increased, suggesting that these are adopted to conserve heat; oblique and dorsal‐up postures (3–4 flippers exposed) use increased with Tbb indicating a role in heat dissipation. The transition between heat conserving and heat dissipating postures occurred at about 14°–20°C (Tbb). Both foreflipper and hind flipper exposure increased with Tbb and the trends were similar, but overall hind flipper exposure was 89% of foreflipper exposure. The results show that surface area of flippers exposed to air is largely controlled by postural adjustment. The increase in flipper exposure with Tbb provides evidence of behavioral thermoregulation and that flippers are major sites for heat loss in the New Zealand sea lion, as observed for other otariid species. Nonpostural thermoregulatory behaviors such as flipper waving and sand flipping increased with Tbb, and may provide additional means of dissipating heat. Total body surface areas of six sea lions ranged from 1.72 to 3.39 m2 (curvilinear length range from 1.60 to 2.35 m), and total flipper surface area averaged 22.7% of total body surface area. As otariids do not employ their hind limbs for aquatic propulsion, their role in behavioral thermoregulation may provide an explanation for the relatively large size of the hind flippers of the New Zealand sea lion.