Estimating animal populations is critical for wildlife management. Aerial surveys are used for generating population estimates, but can be hampered by cost, logistical complexity, and human risk. Additionally, human counts of organisms in aerial imagery can be tedious and subjective. Automated approaches show promise, but can be constrained by long setup times and difficulty discriminating animals in aggregations. We combine unmanned aircraft systems (UAS), thermal imagery and computer vision to improve traditional wildlife survey methods. During spring 2015, we flew fixed-wing UAS equipped with thermal sensors, imaging two grey seal (Halichoerus grypus) breeding colonies in eastern Canada. Human analysts counted and classified individual seals in imagery manually. Concurrently, an automated classification and detection algorithm discriminated seals based upon temperature, size, and shape of thermal signatures. Automated counts were within 95–98% of human estimates; at Saddle Island, the model estimated 894 seals compared to analyst counts of 913, and at Hay Island estimated 2188 seals compared to analysts’ 2311. The algorithm improves upon shortcomings of computer vision by effectively recognizing seals in aggregations while keeping model setup time minimal. Our study illustrates how UAS, thermal imagery, and automated detection can be combined to efficiently collect population data critical to wildlife management.

Studies of the behavioral ecology of seals hauled out on the sea ice at Popham Bay (64°17′ N, 65°30′ W) southeastern Baffin Island were conducted from 8 May to 6 June 1978 and 1 May to 20 June 1979. Similar densities and seasonal changes in numbers of hauled out seals were seen in both years. Seal numbers were positively correlated with date and negatively correlated with wind speed. While lying on the ice seals were vigilant and aggressive towards other seals, and females suckled their pups. Individuals were recognized by their different pelage marks. Both males and females showed site tenacity. One male, seen in 1978, was resighted in the study area in 1979. Our observations indicate that ringed seals are territorial and similar to the polygynous Weddell seal of the antarctic in their social organization. Population regulation appears to be affected by availability of suitable fast ice in which to maintain feeding and breeding habitat, with some adjustment of annual recruitment possibly in response to depleted food resources.

Stable isotopes have become powerful tools for gathering information on food webs in marine ecosystems. The method is based on the concept that the ratio of Nitrogen‐14 to 15N (or Carbon‐12 to 13C) in the tissues of animals is directly related to the ratio found in their diet. Vibrissae provide a time series of stable isotope data as tissue is laid down sequentially over time. Here we examine the growth rate of 283 mystacial (muzzle) vibrissae of four gray seals, Halichoeruas grypus, over a five‐month period to investigate their applicability for stable isotope diet analysis. The individual vibrissae did not grow at a constant rate during the study, Fifty‐nine actively growing vibrissae were modeled to quantify the growth pattern using a three‐parameter von Bertalanffy curve, with the parameters estimated using non‐linear mixed‐effects models. This model incorporated the inherent serial correlation of these data. The growth rate was 0.024 cm/d (95% CI = 0.019–0.030), the asymptotic length differed significantly by location (F3,56=9.64, P < 0.001), but no significant trend was found with muzzle location (F3,56= 0.15, P= 0.93). The Δlength/Δtime between each measurement was calculated and most of these data fell at or near zero growth (median = 0.04 cm/d, range = 0–0.78). Individual vibrissae were shed asynchronously and without any seasonal growth trend. This has serious implications for researchers attempting to extrapolate diet data from vibrissae. Because the growth is neither continuous nor synchronous, it will be a challenge to accurately identify the dates when the isotopes were incorporated into the tissue.

Ringed seals, Phoca hispida, the smallest of the marine arctic pinnipeds, are one of only two seal species in the world adapted to life in the land-fast sea ice. The habitat is characterized by a stable ice platform forming in early winter and lies at latitudes subject to extreme low temperatures. The small body size of adults and semi-altricial pups are an unusual adaptation to cold, allowing ringed seals to use shelters that they construct in the snow overlying their breathing holes. These small subnivean structures act to hide adults and pups from predators, especially polar bears, U r n marifimus, and arctic foxes, Alopex lagopus. It appears that dry lanugal pups could withstand the arctic cold without shelter, but pups that have been wetted become hypothermic and require shelter to regain thermoneutrality. Since female seals actively swim away with their pups from attacks on their birth lairs by foxes and bears, both the physical and the thermal protection of alternate subnivean lairs are important for the survival of the neonate. Weddell seals, Leptonychofes weddelli, resident in the land-fast ice of the Antarctic, are the ecological counterpart of the ringed seal. Their large body size is typical of the usual cold adaptive strategy of other polar phocid seals.

Photographic and visual aerial surveys to determine current pup production of Northwest Atlantic harp seals were conducted off Newfoundland and in the Gulf of St. Lawrence during March 1999‐Photographic surveys were conducted on all whelping concentrations between 14 and 24 March, whereas a visual survey was made of the southern Gulf concentrations on 14 March. Pup production was estimated to be 739,100 (SE = 96,300, CV = 13.0%) at the Front, 82,600 (SE = 22,500, CV = 27.2%) in the northern Gulf, and 176,200 (SE = 25,400, CV = 14.4%) in the southern Gulf (Magdalen Island) for a total of 997,900 (SE = 102,100, 10.2%). Changes in aerial survey estimates indicate that pup production has increased since 1994. A new method to correct for the temporal change in the proportion of pups present on the ice was examined by fitting the percentage of pups observed in three age‐dependent stages to a Normal distribution. The results were compared to those obtained from a more complex model used previously. The Simple model produced slightly higher, and hence more conservative, estimates of the proportion of births that had occurred before the time of the survey than the Complex model. When using the Simple model fewer assumptions regarding the start date of pupping and the proportion of older pups remaining on the ice were required, the herd had to be followed for a shorter period, and a more convenient means of calculating confidence limits was available.

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Predation on ringed seals (Phoca hispida) was examined in Barrow Strait between March and May 1984 to 1986. Polar bears were the most important predator. Evidence of bear predation was observed at 18–30% of the ringed seal subnivean structures we located. Ten to 24% of predation attempts were successful, with pups making up 75% to 100% of the seals killed. Bears killed an average of 0.08 to 0.51 seals/km2, which comprised 8 to 44% of the estimated annual pup production. Bears were successful on average in 11.3% of their attempts to kill pups hidden inside birth lairs. On southeast Baffin Island where snow was soft and pups were exposed, bears were successful in 33.5% of their attempts to kill a seal. Negative correlations were found between mean snow depth and predation by polar bears (r= ‐0.896, P= 0.04, n= 5) in 1985, and between snow depth and the number of predation attempts (r= ‐0.613, P= 0.02, n= 14) in 1986.

Hooded seals (Cystophora cristata) lactate for 3.6 days during which females simultaneously fast and transfer large amounts of energy to their pups through fat-rich milk. Pups grow rapidly, principally due to blubber deposition. Lipoprotein lipase (LPL), the primary enzyme responsible for tissue uptake of triglyceride fatty acids, may strongly influence both maternal milk fat secretion and pup blubber deposition. We measured the energetic costs of lactation (using hydrogen isotope dilution, 3H2O), milk composition, prolactin, and LPL activity (post-heparin plasma LPL [PH LPL], blubber, mammary gland and milk; U) in six females. PH LPL and blubber LPL were measured in their pups. Females depleted 216.3 MJ.day-1 of body energy and fat accounted for 59% of maternal mass loss and 90% of postpartum body energy loss, but maternal body composition changed little. Maternal blubber LPL was negligible (0.0-0.2 U), while mammary LPL was elevated (1.8-2.5 U) and was paralleled by changes in prolactin. Estimated total mammary LPL activity was high (up to 20,000 U.animal-1) effectively favoring the mammary gland for lipid uptake. Levels of total blubber LPL in pups increased seven-fold over lactation. Pups with higher PH LPL at birth had greater relative growth rates (P = 0.025). Pups with greater blubber stores and total blubber LPL activity had elevated rates of fat deposition (P = 0.035).