Time-lapse infrared videography for animal behavior observations

Although videography has been used for many years to record episodes of animal behavior, the availability of increasingly complex equipment can make selection difficult. Most equipment developed for round-the-clock observations was designed for security surveillance, so informed purchasing, installation, and usage decisions need to be made to monitor animal behavior effectively. During 7 years of using video and infrared equipment for animal behavior research and monitoring in a zoo setting, we tested many models, evaluated options, and modified components. We now have well-integrated systems that are compatible with our video/computer review and analysis program. New equipment will continue to become available, but familiarity with basic features and applications can help to narrow the selection. Zoo Biol 17:535–543, 1998. © 1998 Wiley-Liss, Inc.     

A novel camera trapping method for individually identifying pumas by facial features

Camera traps (CTs), used in conjunction with capture–mark–recapture analyses (CMR; photo‐CMR), are a valuable tool for estimating abundances of rare and elusive wildlife. However, a critical requirement of photo‐CMR is that individuals are identifiable in CT images (photo‐ID). Thus, photo‐CMR is generally limited to species with conspicuous pelage patterns (e.g., stripes or spots) using lateral‐view images from CTs stationed along travel paths. Pumas (Puma concolor) are an elusive species for which CTs are highly effective at collecting image data, but their suitability to photo‐ID is controversial due to their lack of pelage markings. For a wide range of taxa, facial features are useful for photo‐ID, but this method has generally been limited to images collected with traditional handheld cameras. Here, we evaluate the feasibility of using puma facial features for photo‐ID in a CT framework. We consider two issues: (1) the ability to capture puma facial images using CTs, and (2) whether facial images improve human ability to photo‐ID pumas. We tested a novel CT accessory that used light and sound to attract the attention of pumas, thereby collecting face images for use in photo‐ID. Face captures rates increased at CTs that included the accessory (n = 208, χ ² = 43.23, p ≤ .001). To evaluate if puma faces improve photo‐ID, we measured the inter‐rater agreement of 5 independent assessments of photo‐ID for 16 of our puma face capture events. Agreement was moderate to good (Fleiss’ kappa = 0.54, 95% CI = 0.48–0.60), and was 92.90% greater than a previously published kappa using conventional CT methods. This study is the first time that such a technique has been used for photo‐ID, and we believe a promising demonstration of how photo‐ID may be feasible for an elusive but unmarked species.     

Counterpoint to “Infrared cameras overestimate skin temperature during rewarming from cold exposure”

We evaluated the paper by Maley et al. (2020) in this journal “Infrared cameras overestimate skin temperature during rewarming from cold Exposure” for the evidence provided in support of its title and conclusions. Several methodological issues were identified as well as issues with the data interpretation: 1: Only one camera was used but a conclusion was made for ‘cameras’ in general; 2: The camera accuracy (±2 °C) is too low to do a meaningful comparison without using local reference values or an on-site calibrator with higher accuracy; 3: Thermistor measurements are taken as a gold standard while issues such as temperature gradients and taping are known; 4: Both methods are not compared at the same location and a natural, physiological, gradient may be present between their locations; 5. The impact of the sensor and tape on delays in the change of the underlying tissue temperature is not considered; 6: Only a single pixel was used for the analysis, which has been shown to be problematic.We concluded that the paper by Maley et al. does not provide conclusive evidence that infrared cameras overestimate skin temperature during rewarming from cold exposure.     

Synthesis and structural analysis of copper(II) cysteine complexes

This report describes the synthesis and structural analysis of stable copper(II) cysteine complexes. Pale pink copper(II) cysteine complexes were synthesized in mole ratios of 1:2, 1:4, and 1:6 of copper(II):cysteine in ethanol. Infrared spectroscopy and X-ray absorption spectroscopy confirmed that copper(II) binding occurred via the thiol ligand of cysteine. XANES analysis showed that the oxidation state of copper remained as copper(II) and the local atomic geometry was similar in all of the cysteine complexes. The EXAFS data indicate that the copper(II) cysteine complexes are forming ring type structures with sulfur ligands from the cysteines acting as bridging ligands. X-ray diffraction revealed that the copper(II) cysteine complexes formed monoclinic cells with maximum crystallinity found in the 1:4 copper(II):cysteine complex.     

Better safe than sorry: The response to a simulated predator and unfamiliar scent by the European hare

Predator presence can create a “landscape of fear,” which is defined as the spatially explicit distribution of perceived predation risk as seen by prey. Prey species can alter their behavior and space use as a response to increased predation risk, which might be traded off with energetic requirements. Thus, whether or not an anti-predator behavior is performed might depend on the perceived risk. In this study, we investigated the behavioral and spatial response of the European hare (Lepus europaeus) toward the presence of a predator scent, using red fox (Vulpes vulpes) scat, an unfamiliar control scent (butyric acid), and a true control (no scent). We collected data on hare activity times and behavior using 50 camera trap locations and spatial data using GPS telemetry (30,481 GPS positions of 12 hares). Hares showed spatial anti-predator behaviors within their home range, for example, the local avoidance of areas treated with scent and remaining further from field edges, in response to sympatric predator scent and partly also in response to unfamiliar butyric acid. Conversely, more costly anti-predator behaviors, that is, increased vigilance at the expense of foraging, were only shown in response to the predator scent. Our results suggest that prey species respond flexibly toward scent cues, utilizing less costly anti-predator behaviors independent of the perceived threat, whereas costly anti-predator responses are only used in the presence of “real” threat. Further, our findings emphasize that a combination of camera trap and GPS data can provide detailed information on animal behavior and space use, and caution that interpretation of one data source alone might lead to incomplete conclusions.     

Infrared cameras overestimate skin temperature during rewarming from cold exposure

ObjectiveThe primary aim of this study was to assess the accuracy of an infrared camera and that of a skin thermistor, both commercially available. The study aimed to assess the agreement over a wide range of skin temperatures following cold exposure.MethodsFifty-two males placed their right hand in a thin plastic bag and immersed it in 8 °C water for 30 min whilst seated in an air temperature of 30 °C. Following hand immersion, participants removed the bag and rested their hand at heart level for 10 min. Index finger skin temperature (T_sk) was measured with a thermistor, affixed to the finger pad, and an infrared camera measured 1 cm distally to the thermistor. Agreement between the infrared camera and thermistor was assessed by mean difference (infrared camera minus thermistor) and 95% limits of agreement analysis, accounting for the repeated measures over time. The clinically significant threshold for T_sk differences was set at ±0.5 °C and limits of agreement ±1 °C.ResultsAs an average across all time points, the infrared camera recorded T_sk 1.80 (SD 1.16) °C warmer than the thermistor, with 95% limits of agreement ranging from −0.46 °C to 4.07 °C.ConclusionCollectively, the results show the infrared camera overestimated T_sk at every time point following local cooling. Further, measurement of finger T_sk from the infrared camera consistently fell outside the acceptable level of agreement (i.e. mean difference exceeding ±0.5 °C). Considering these results, infrared cameras may overestimate peripheral T_sk following cold exposure and clinicians and practitioners should, therefore, adjust their risk/withdrawal criteria accordingly.     

Body temperature in premature infants during the first week of life: Exploration using infrared thermal imaging

BackgroundHypothermia is a problem for very premature infants after birth and leads to increased morbidity and mortality. Previously we found very premature infants exhibit abnormal thermal patterns, keeping foot temperatures warmer than abdominal temperatures for their first 12 h of life.PurposeWe explored the utility of infrared thermography as a non-invasive method for measuring body temperature in premature infants in an attempt to regionally examine differential temperatures.ResultsOur use of infrared imaging to measure abdominal and foot temperature for extremely premature infants in heated, humid incubators was successful and in close agreement using Bland and Altman technique with temperatures measured by skin thermistors.ConclusionsOur study methods demonstrated that it was feasible to capture full body temperatures of extremely premature infants while they were resting in a heated, humid incubator using a Flir SC640 infrared camera. This technology offers researchers and clinicians a method to examine acute changes in perfusion differentials in premature infants which may lead to morbidity.     

Thermal body patterns for healthy Brazilian adults (male and female)

The aim of this study was to establish the skin temperature (T_sk) thermal profile for the Brazilian population and to compare the differences between female and male Brazilian adults. A total of 117 female and 103 male were examined with a thermographic camera. The T_sk of 24 body regions of interest (ROI) were recorded and analyzed. Male T_sk results were compared to female and 10 ROI were evaluated with respect to the opposite side of the body (right vs. left) to identify the existence of significant contralateral T_sk differences (ΔT_sk). When compared right to left, the largest contralateral ΔT_sk was 0.3 °C. The female vs. male analysis yielded significant differences (p<0.05) in 13 of the 24 ROI. Thigh regions, both ventral and dorsal, had the highest ΔT_sk by sex (≈1.0 °C). T_sk percentile below P₅ or P₁₀ and over P₉₀ or P₉₅ may be used to characterize hypothermia and hyperthermia states, respectively. Thermal patterns and T_sk tables were established for Brazilian adult men and women for each ROI. There is a low T_sk variation between sides of the body and gender differences were only significant for some ROIs.     

Quantifying torpor in small mammals non-invasively using infrared thermocouples

Measurements of torpor use are pivotal for many research areas concerning the thermal biology of endotherms. Here, I used infrared thermocouples to non-invasively examine torpor patterns in the small marsupial fat-tailed dunnart (Sminthopsis crassicaudata). Sensors were installed inside the nesting chambers to continuously monitor fur temperature in undisturbed animals. Firstly, to verify the measurements, fur temperature was monitored simultaneously with body temperature using internal radio transmitters (n=6). Secondly, I conducted a food restriction study to demonstrate the reliability of the method within a physiological experiment (n=8). Based on the correspondence of simultaneously measured fur and body temperature during torpor bouts, I was able to confirm that infrared thermocouples provide reliable temporal information on torpor patterns. Furthermore, torpor use was successfully monitored over a 20-day food restriction study. The method can easily be adapted to suit other small mammal or bird species and presents a useful, inexpensive approach for examining torpor patterns remotely and non-invasively in the laboratory.