Surface temperature patterns in seals and sea lions: A validation of temporal and spatial consistency

Nienaber, Jeanette; Thomton, Jamie D.; Horning, Markus; Polasek, Lori; Mellish, Jo‐Ann E.

doi:10.1016/j.jtherbio.2010.09.005

Cited by 21 publications

(19 citation statements)

References 32 publications

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“…They neither hauled out voluntarily, nor were they in a training situation, but they were cut off from the water, which is generally not a relaxed situation for a seal. Nienaber et al (2010) observed a slightly increased temperature in some less insulated body regions when the harbor seals were kept ashore by training, similar to the results of our study. But thermal windows according to our definition (high temperature difference, clearly visible borders, see above) were not found.…”

Section: Training Versus Hauling Out Situationssupporting

confidence: 91%

“…in the investigations of flukes and fins of bottlenose dolphins (Tursiops truncatus M.) and their function as thermal windows by Williams et al (1999) and Barbieri et al (2010). Nienaber et al (2010) proved IRT a useful and accurate technique for the measurement of surface temperatures even in the field and showed experimentally the minimal influence of environmental parameters on the accuracy of the measured temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Control and amount of heat dissipation through thermal windows in harbor seals (Phoca vitulina)

Erdsack

Hanke

Dehnhardt

et al. 2012

Journal of Thermal Biology

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Section: Training Versus Hauling Out Situationssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Control and amount of heat dissipation through thermal windows in harbor seals (Phoca vitulina)

Erdsack

Hanke

Dehnhardt

et al. 2012

Journal of Thermal Biology

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“…Last, the distance between the object and the TIR camera (i.e. shooting distance) is among the main factors supposed to impact temperature values in TIR images (Nienaber et al, 2010;Cilulko et al, 2013). Like any image, TIR images are composed of pixels, and the portion of object surface area included in a single pixel directly depends on shooting distancewith larger area included in each pixel as shooting distance increases.…”

Section: Introductionmentioning

confidence: 99%

Distance makes the difference in thermography for ecological studies

Faye

Dangles

Pincebourde

2016

Journal of Thermal Biology

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Surface temperature drives many ecological processes and infrared thermography is widely used by ecologists to measure the thermal heterogeneity of different species' habitats. However, the potential bias in temperature readings caused by distance between the surface to be measured and the camera is still poorly acknowledged. We examined the effect of distance from 0.3 to 80m on a variety of thermal metrics (mean temperature, standard deviation, patch richness and aggregation) under various weather conditions and for different structural complexity of the studied surface types (various surfaces with vegetation). We found that distance is a key modifier of the temperature measured by a thermal infrared camera. A non-linear relationship between distance and mean temperature, standard deviation and patch richness led to a rapid under-estimation of the thermal metrics within the first 20m and then only a slight decrease between 20 and 80m from the object. Solar radiation also enhanced the bias with increasing distance. Therefore, surface temperatures were under-estimated as distance increased and thermal mosaics were homogenized at long distances with a much stronger bias in the warmer than the colder parts of the distributions. The under-estimation of thermal metrics due to distance was explained by atmospheric composition and the pixel size effect. The structural complexity of the surface had little effect on the surface temperature bias. Finally, we provide general guidelines for ecologists to minimize inaccuracies caused by distance from the studied surface in thermography.

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“…polygon around the visible body of the seal, and by measuring mean fore flipper surface temperature T f ( o C) from spot measurement at the axillary, as this is an important thermal window (Mauck et al, 2003;Nienaber et al, 2010) ( Fig.2A). For transects and quadrat data, mean surface temperature of the aggregation T h ( o C) was determined by fitting a polygon around all visible bodies of aggregated seals and T f from spot measurement from visible axillary of each seal (Fig.2B).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Environmental and physiological determinants of huddling behavior of molting female southern elephant seals (Mirounga leonina)

Chaise

McCafferty

Krellenstein

et al. 2019

Physiology & Behavior

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While endotherms can rely on their insulation to reduce heat loss to adapt to cold environments, renewing of fur during molt impairs insulation while they have to perfuse the periphery to support epidermal tissues. The southern elephant seal Mirounga leonina undertakes an annual catastrophic molt while fasting on land in a wet, windy and cold environment. However, southern elephant seals show characteristic aggregation patterns that are predicted to reduce high metabolic costs during the molt. Between 2012 and 2016, 59 female elephant seals were tracked on land during their molt to study their aggregation behavior in relation to molt stage, habitat type and local weather conditions. Infrared thermography and stomach temperature loggers were used to observe variation in body surface and internal temperature in relation to molt stage and aggregation behavior. We found that thermal constraints varied during the molt, with a peak in surface temperature during the mid-stage of the molt. Wallows (mud pools) appear as favorable habitat to aggregate while molting. Indeed, wallows offered a warmer microclimate with greater ground temperature and lower wind speed. Moreover, there was a greater proportion of aggregated seals and larger group size in wallows. These aggregation patterns in wallows were influenced by local weather such that a greater proportion of seals were located in the center of the aggregation, and larger group size occurred during days of unfavorable meteorological conditions. We also observed a higher proportion of seals at mid-stage of molt amongst aggregated seals compared to isolated individuals. This aggregation behavior may reduce the cost of thermogenesis as surface body temperature and stomach temperature were cooler by 1.0°C and 1.5°C, respectively, in aggregated compared to isolated seals. As a consequence, huddling behavior may be thermally advantageous for female southern elephant seals during the molt.

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Surface temperature patterns in seals and sea lions: A validation of temporal and spatial consistency

Cited by 21 publications

References 32 publications

Control and amount of heat dissipation through thermal windows in harbor seals (Phoca vitulina)

Control and amount of heat dissipation through thermal windows in harbor seals (Phoca vitulina)

Distance makes the difference in thermography for ecological studies

Environmental and physiological determinants of huddling behavior of molting female southern elephant seals (Mirounga leonina)

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