Temperature regulation and microhabitat choice by free-ranging Galapagos fur seal pups (Arctocephalus galapagoensis)

Limberger, Dominique; Trillmich, Fritz; Biebach, Herbert; Stevenson, R. D.

doi:10.1007/bf00399037

Cited by 38 publications

(26 citation statements)

References 19 publications

(19 reference statements)

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“…Equation 2 is similar in some ways to the "operative environmental temperature" (OET) equations derived by Bakken and Gates (1975) and others (see Bakken 1981), which have recently been applied to pinnipeds (Limberger et al 1986;Trites 1991). There are, however, very significant differences between the two types of equations.…”

Section: Discussionmentioning

confidence: 92%

“…More quantitatively, where a,,, is the absorptivity of the seal's surface to the shortwave radiation (a decimal fraction, assumed to be 0.87 (Limberger et al 1986)); a,,, is the absorptivity of the seal's surface to longwave radiation (>0.97 for most animal surfaces; Monteith 1973); S is measured solar radiation (W . m-2); E, is atmospheric longwave emissivity (another decimal fraction; see below); a is the StefanBoltzmann constant (5.673 .…”

Section: Discussionmentioning

confidence: 99%

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Thermal constraints on hauling out by harbour seals (Phoca vitulina)

Watts¹

1992

Can. J. Zool.

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WATTS, P. 1992. Thermal constraints on hauling out by harbour seals (Phoca vitulina). Can. J. Zool. 70: 553 -560.Measurements of the thermal environment were made in conjunction with regular counts of hauled out harbour seals at three sites in the Pacific Northwest. Solar radiation, wind speed, and air temperature were all significantly correlated with numbers of seals on land. These were incorporated into a thermal index of heat flux (expressed in watts per square metre) between the seal and its environment. Numbers of seals hauled out at midday declined sharply as flux increased above 0 W . m-2 (i.e., when seals theoretically gained net heat from their environment), but remained constant at all measured negative values of flux. This relationship could be described by a nonlinear piecewise regression equation ( t d j = 0.648). No significant differences in hauling activity were detected between sites throughout most of the year. During the summer, however, one site with significantly higher mean flux than the others also exhibited significantly lower hauling activity. These findings are consistent with the hypothesis that under temperate summer conditions, hauling out can result in overheating. This may be an important constraint on hauling behaviour. WATTS, P. 1992. Thermal constraints on hauling out by harbour seals (Phoca vitulina). Can. J. Zool. 70 : 553-560. Des mesures de l'environnement thermique ont CtC prises lors du dknombrement de Phoques communs en repos hors de l'eau B trois sites du Nord-Ouest amkricain. Les variables suivantes, radiation solaire, vitesse du vent et tempkrature de l'air, Ctaient toutes en corrklation significative avec le nombre de phoques hors de l'eau. Ces variables ont CtC incorporkes B un indice thermique du flux de chaleur (exprim6 en watts par mktre carrC) entre le phoque et son environnement. Le nombre de phoques hors de l'eau au milieu de la journCe diminuait brusquement au moment oh l'indice atteignait des valeurs supCrieures B 0 W -m-2 (i.e., lorsque les phoques faisaient thkoriquement des gains nets de chaleur), mais ce nombre Ctait constant B toutes les valeurs nCgatives de flux. La relation pourrait &re dCcrite par une Cquation de rkgression non linCaire segmentCe (rzdj = 0,648

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Thermal constraints on hauling out by harbour seals (Phoca vitulina)

Watts¹

1992

Can. J. Zool.

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“…Further, the greater availability of rocky areas provided by these new places might be an important feature for females when choosing the most suitable habitat for pupping and raising their young. Rocky areas are essential for sea lion pups in providing shaded areas and small swimming pools that are suitable for acquiring swimming skills (Limberger et al 1986, González-Suárez & Gerber 2008. Pinnipeds inhabiting lower latitudes often de monstrate special habitat requirements to avoid thermal stress, and this may lead to changes in habitat use preferences and mating systems, in which males often patrol resting sites that have direct ac cess to the water, which are valued by females (Campagna & Le Boeuf 1988).…”

Section: Seasonal Changes In Distributionmentioning

confidence: 99%

Environment-driven changes in terrestrial habitat use and distribution of the Galapagos sea lion

Montero¹,

Páez‐Rosas²,

Murillo³

et al. 2014

Endang. Species. Res.

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Understanding habitat use patterns of marine apex predators is of paramount importance for the effective design of conservation plans. Due to their amphibious life cycle, pinnipeds are one of the most vulnerable groups to habitat loss and degradation. Reducing knowledge gaps that still exist regarding temporal changes in tropical pinniped habitat use is therefore of particular importance for conservation efforts. We analyzed terrestrial habitat use phenology of a tropical otariid, the Galapagos sea lion Zalophus wollebaeki. Regular land-based censuses were carried out in Wreck Bay of San Cristóbal Island, Galapagos, between 2008 and 2012 to explore seasonal changes in sea lion abundance, distribution, and preferences among different habitat types. A daily cycle of haul-out patterns was observed. Animals aggregated on sandy beaches during the coldest periods of the day and were more abundant on rocky and artificial structures when air temperature was warmer. The use of artificial floating platforms as resting places by Z. wollebaeki was described for the first time and linked to environmental variability, suggesting that this may be a successful management tool for pinnipeds inhabiting low latitudes. Further, this species demonstrated seasonal distribution changes, aggregating in high densities during warm seasons and maintaining more even distributions during cold seasons. Sea surface temperature, air temperature, and the onset of the breeding season were the variables that most significantly influenced haul-out patterns of Z. wollebaeki, indicating that this species can adapt to changing environmental conditions by displaying a high degree of plasticity regarding its distribution and terrestrial microhabitat preferences.

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“…Potential specific strategies might entail reducing energy expenditures through suppressing reproductive funaions or reducing production work (i.e., decreasing body growth or sacrificing body energy stores; Stini 1969;Calkins et al 1998). Reducing activity levels and time spent in thermally challenging environments is another strategy (Limberger et al 1986;Nash 1998), as is decreasing basal metabolic rate or minimizing thermoreguiatory costs through social aggregation (Ohata and Miller 1977;Rosen and Trites 1999). The set of strategies actually employed can affect the individual's capacity to survive and reproduce in tbe wild Iwasted as heat Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Energy Reallocation during and after Periods of Nutritional Stress in Steller Sea Lions: Low‐Quality Diet Reduces Capacity for Physiological Adjustments

Jeanniard‐du‐Dot

Rosen²,

Trites³

2009

Physiological and Biochemical Zoology

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Two groups of female Steller sea lions (groups H and P) were subjected to periods of energy restriction and subsequent refeeding during winter and summer to determine changes in energy partitioning among principal physiological functions and the potential consequences to their fitness. Both sea lion groups consumed high-quality fish (herring) before and after the energy restrictions. During restrictions, group H was fed a lower quantity of herring and group P a caloric equivalent of low-quality fish (pollock). Quantitative estimates of maintenance and production energies and qualitative estimates of thermoregulation, activity, and basal metabolic rate were measured. During summer, all animals compensated for the imposed energy deficit by releasing stored energy (production energy). Group H also optimized the energy allocation to seasonal conditions by increasing activity during summer, when fish are naturally abundant (foraging effort), and by decreasing thermoregulation capacity when waters are warmer. During winter, both groups decreased the energy allocated to overall maintenance functions (basal metabolic rate, thermoregulation, and activity together) in addition to releasing stored energy, but they preserved thermoregulatory capacity. Group H also decreased activity levels in winter, when foraging in the wild is less efficient, unlike group P. Overall, sea lions fed pollock did not change energy allocation to suit environmental conditions as readily as those fed herring. This implies that a low energy-density diet may further reduce fitness of animals in the wild during periods of nutritional stress.

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Temperature regulation and microhabitat choice by free-ranging Galapagos fur seal pups (Arctocephalus galapagoensis)

Cited by 38 publications

References 19 publications

Thermal constraints on hauling out by harbour seals (Phoca vitulina)

Thermal constraints on hauling out by harbour seals (Phoca vitulina)

Environment-driven changes in terrestrial habitat use and distribution of the Galapagos sea lion

Energy Reallocation during and after Periods of Nutritional Stress in Steller Sea Lions: Low‐Quality Diet Reduces Capacity for Physiological Adjustments

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