Detecting Denning Polar Bears with Forward-Looking Infrared (FLIR) Imagery

Amstrup, Steven C.; York, Geoff; McDonald, Trent L.; Nielson, Ryan M.; Simac, Kristin S.

doi:10.1641/0006-3568(2004)054[0337:ddpbwf]2.0.co;2

Cited by 42 publications

(77 citation statements)

References 13 publications

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“…reported 187 the mean den roof thicknesses for 22 polar bear dens in northern Alaska was 72 ± 87 cm, and 188 ranged from as little as 10cm to as much as 400 cm. Snow depth over many dens, therefore, 189 is likely near or above FLIR detection capabilities, regardless of weather-corroborating the 190 conclusion ofAmstrup et al (2004) that some dens will never be detected with FLIR.191Mid-winter den abandonment may account for some putative den locations that we 192 found not to be actual dens. More hotspots not associated with den emergence (36% of all 193 putative den sites,Table 1), were reported by industry AFS than the actual number of dens 194 detected.…”

supporting

confidence: 57%

Efficacy of aerial forward-looking infrared surveys for detecting polar bear maternal dens

Smith

Amstrup

Kirschhoffer³

et al. 2019

Preprint

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20Denned polar bears are invisible under the snow, therefore winter-time petroleum 21 exploration and development activities in northern Alaska have potential to disturb maternal 22 polar bears and their cubs. Previous research determined forward looking infrared (FLIR) 23 imagery could detect many polar bear maternal dens under the snow, but also identified 24 limitations of FLIR imagery. We evaluated the efficacy of FLIR-surveys conducted by oil-field 25 operators from 2004-2016. Aerial FLIR surveys detected 15 of 33 (45%) and missed 18 (55%) 26 of the dens known to be within surveyed areas. While greater adherence to previously 27 recommended protocols may improve FLIR detection rates, the physical characteristics of polar 28 bear maternal dens, increasing frequencies of weather unsuitable for FLIR detections-caused by 29 global warming, and competing "hot spots" are likely to prevent FLIR surveys from detecting 30 maternal dens reliably enough to afford protections consonant with increasing global threats to 31 polar bear welfare.

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supporting

confidence: 57%

Efficacy of aerial forward-looking infrared surveys for detecting polar bear maternal dens

Smith

Amstrup

Kirschhoffer³

et al. 2019

Preprint

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“…Ongoing research by the U.S. Geological Survey provided precise den locations for observation in 2002 -03 through radiotelemetry (Amstrup, 2000) or the use of forward-looking infrared (FLIR) imagery (Amstrup et al, 2004) (Fig. 1).…”

Section: Den Site Selection and Observationmentioning

confidence: 99%

Post-Den Emergence Behavior of Polar Bears (<i>Ursus maritimus</i>) in Northern Alaska

Smith¹,

Partridge²,

Amstrup³

et al. 2009

ARCTIC

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ABSTRACT. We observed polar bear (Ursus maritimus) maternity den sites on Alaska's North Slope in March 2002 and in an effort to describe bears' post-den emergence behavior. During 40 sessions spanning 459 h, we observed 8 adults and 14 dependent cubs outside dens for 37.5 h (8.2% of total observation time). There was no significant difference between den emergence dates in 2002 (mean = 15 Mar ± 4.1 d) and 2003 (mean = 21 Mar ± 2.1 d). Following initial den breakout, polar bears remained at their den sites for 1.5 to 14 days (mean = 8.1 ± 5.1 d). The average length of stay in dens between emergent periods was significantly shorter in 2002 (1.79 h) than in 2003 (4.82 h). While outside, adult bears were inactive 49.5% of the time, whereas cubs were inactive 13.4% of the time. We found no significant relationships between den emergence activity and weather. Adult polar bears at den sites subjected to industrial activity exhibited significantly fewer bouts of vigilance than denned bears in undisturbed areas (t = -5.5164, df = 4, p = 0.00). However, the duration of vigilance behaviors at sites near industrial activity was not significantly shorter than at the other sites studied (t = -1.8902, df = 4, p = 0.07). Results for these bears were within the range of findings in other studies of denned polar bears. ,82 h). Une fois sortis, les ours adultes étaient inactifs pendant 49,5 % du temps, tandis que les oursons étaient inactifs pendant 13,4 % du temps. Nous n'avons pas trouvé de lien important entre l'activité une fois sorti de la tanière et le temps qu'il faisait. Les ours polaires adultes à l'emplacement de tanières assujetties à des activités industrielles affichaient beaucoup moins de séquences de vigilance que les ours en tanière des régions tranquilles (t = -5,5164, dl = 4, p = 0,00). Cependant, la durée des comportements de vigilance aux emplacements situés près d'activités industrielles n'était pas beaucoup plus courte qu'aux autres emplacements étudiés (t = -1,8902, dl = 4, p = 0,07). Les résultats enregistrés pour ces ours tombaient dans l'étendue des constatations découlant d'autres études d'ours polaires en tanière.Mots clés : Alaska, comportement, sortie de la tanière, tanière de maternité, versant nord, ours polaire, Ursus maritimus Traduit pour la revue Arctic par Nicole Giguère.

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“…Thermal imaging has been used in the field to detect denning polar bears under the snow [25]. The internal den temperature can be as high as 30˝C resulting in average surface temperatures over dens 10˝C higher than surrounding snow banks ( [26] as cited in [27]). Even with this very large contrast in temperatures, and under favorable conditions, Amstrup et al, (2004) [27] were only able to detect 83% of 23 known dens.…”

Section: Introductionmentioning

confidence: 99%

Spectral Reflectance of Polar Bear and Other Large Arctic Mammal Pelts; Potential Applications to Remote Sensing Surveys

et al. 2016

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Spectral reflectance within the 350-2500 nm range was measured for 17 pelts of arctic mammals (polar bear, caribou, muskox, and ringed, harp and bearded seals) in relation to snow. Reflectance of all pelts was very low at the ultraviolet (UV) end of the spectrum (<10%), increased through the visual and near infrared, peaking at 40%-60% between 1100 and 1400 nm and then gradually dropped, though remaining above 20% until at least 1800 nm. In contrast, reflectance of snow was very high in the UV range (>90%), gradually dropped to near zero at 1500 nm, and then fluctuated between zero and 20% up to 2500 nm. All pelts could be distinguished from clean snow at many wavelengths. The polar bear pelts had higher and more uniform averaged reflectance from about 600-1100 nm than most other pelts, but discrimination was challenging due to variation in pelt color and intensity among individuals within each species. Results suggest promising approaches for using remote sensing tools with a broad spectral range to discriminate polar bears and other mammals from clean snow. Further data from live animals in their natural environment are needed to develop functions to discriminate among species of mammals and to determine whether other environmental elements may have similar reflectance.

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Detecting Denning Polar Bears with Forward-Looking Infrared (FLIR) Imagery

Cited by 42 publications

References 13 publications

Efficacy of aerial forward-looking infrared surveys for detecting polar bear maternal dens

Efficacy of aerial forward-looking infrared surveys for detecting polar bear maternal dens

Post-Den Emergence Behavior of Polar Bears (<i>Ursus maritimus</i>) in Northern Alaska

Spectral Reflectance of Polar Bear and Other Large Arctic Mammal Pelts; Potential Applications to Remote Sensing Surveys

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