Stress-coping styles dictate how individuals react to stimuli and can be measured by the integrative physiological parameter of resting heart-rate variability (HRV); low resting HRV indicating proactive coping styles, while high resting HRV typifies reactive individuals. Over 5 successive breeding seasons we measured resting HRV of 57 lactating grey seals. Mothers showed consistent individual differences in resting HRV across years. We asked whether proactive and reactive mothers differed in their patterns of maternal expenditure and short-term fitness outcomes within seasons, using maternal daily mass loss rate to indicate expenditure, and pup daily mass gain to indicate within season fitness outcomes. We found no difference in average rates of maternal daily mass loss or pup daily mass gain between proactive and reactive mothers. However, reactive mothers deviated more from the sample mean for maternal daily mass and pup daily mass gain than proactive mothers. Thus, while proactive mothers exhibit average expenditure strategies with average outcomes, expenditure varies much more among reactive mothers with more variable outcomes. Overall, however, mean fitness was equal across coping styles, providing a mechanism for maintaining coping style diversity within populations. Variability in reactive mothers’ expenditures and success is likely a product of their attempts to match phenotype to prevailing environmental conditions, achieved with varying degrees of success.

Drones, or unoccupied aircraft systems (UAS), can transform the way scientific information on wildlife populations is collected. UAS surveys produce accurate estimates of ground-nesting seabirds and a variety of waterbirds, but few studies have examined the trade-offs of this methodology for counting cliff-nesting seabirds. In this study, we examined how different UAS survey parameters might influence seabird counts for population monitoring and assessed behavioral responses to aerial surveys for three sub-Arctic seabird taxa in the Gulf of Alaska: common murres (Uria aalge), black-legged kittiwakes (Rissa tridactyla), and pelagic and double-crested cormorants (Phalacrocorax pelagicus and Phalacrocorax auritus). We flew two commercially available models of UAS in planned approaches at different speeds and distances from colonies during incubation and chick-rearing periods. We compared counts from UAS-derived images with those from vessel-based photography and assessed video recordings of individual birds’ behaviors for evidence of disturbance during UAS operations and control phases. Count estimates from UAS images were similar to or higher than those from conventional vessel-based images, and UAS were particularly effective at photographing birds at sites with high cliff walls or complex topography. We observed no significant behavioral responses to the UAS by murres or cormorants, but we did observe flushing by black-legged kittiwakes during UAS flights; most of these birds were not incubating or brooding. At both the colony and individual level, we observed slightly greater responses to the smaller UAS platform and closer approaches. These results inform both species specific and general best practices for research and recreational usage of UAS near cliff-nesting seabird colonies.

Recent advances in satellite tagging technologies for marine animals have provided opportunities to investigate the spatial ecology of pelagic species including at-sea behavior and predator–prey interactions. Implantable Life History Transmitters (LHX tags) provide postmortem data on location and causes of mortalities from tagged individuals. Following a mortality event and extrusion of the tag from within an animal, varying amounts of time may elapse between the onset of satellite transmissions, the first successful uplinks to the Argos satellite system and the first location estimate obtained from multiple uplinks. Externally attached pop-up archival transmitters (PAT tags) also only commence transmissions following pre-programmed detachment from a host. The amount of delay for both types of tags may vary with programming, sea state (e.g., wind, waves, currents and tides) tag exposure and satellite coverage. Thus, actual emergence locations for LHX and other pop-up satellite transmitters are hard to accurately determine. Larger errors (~ 10–50 km) may be associated with emergence locations than the errors inherent in the Argos system. Here we present a new approach based on a time-reversed state-space model to improving emergence location estimates and quantifying their uncertainty for pop-up satellite transmitters, using data from 24 LHX tags deployed at known locations in the Gulf of Alaska. Between May and June 2017, we deployed 12 LHX tags in two locations in Resurrection Bay and 12 tags in two locations in Prince William Sound, Alaska. When tracking models included all successful uplinks that resulted in Argos locations immediately after deployments, the emergence location could be predicted to within 3 km, on average. However, increasing transmission delays up to 16 h progressively reduced the accuracy to 6–12 km, and for delays of 24 h or longer, the actual emergence locations were outside of the 95% isopleth of estimates. Emergence locations for pop-up satellite transmitters can be estimated by a time-reversed state-space model. The area confined by 95% isopleth of model output is an effective way to characterize an emergence location with an associated uncertainty. Our findings illustrate the importance of programming tags to enhance satellite uplinks to provide immediate and high-quality locations.

With their large size, the foraging behaviors of adult male Steller sea lions Eumetopias jubatus may have significant impacts on marine food webs and ecosystems. Limited studies from scat suggest that male and female Steller sea lions exhibit some dietary differences, and bycatch rates tend to be higher for males; however, most foraging ecology data are from adult females. Here we aimed to (1) characterize the isotopic foraging niches of adult male Steller sea lions in the Aleutian Islands and Bering Sea (n = 18), (2) assess sex-specific resource partitioning between male and female Steller sea lions (n = 18) in this region, and (3) identify male foraging strategies associated with greater total mercury concentrations ([THg]), a contaminant of concern in the region. Vibrissae collected from males bycaught in commercial fisheries from 1998-2017 were sectioned, and sequential segments were analyzed for bulk stable isotope ratios (δ¹⁵N and δ¹³C values) and [THg]. Individuals exhibited temporal oscillations in both δ¹⁵N and δ¹³C values that reflect significant summer to winter variation in foraging. Male Steller sea lions had larger isotopic niches than females, and limited overlap of isotopic niches suggests a moderate degree of sex-specific resource partitioning in this system. [THg] were positively associated with δ¹⁵N, and individuals exhibited evidence of bioaccumulation with age. These findings represent contemporary isotopic values and the first reported Hg levels for non-pup male Steller sea lions in a region where the population is considered endangered. Together, they provide a reference for assessing shifts in foraging patterns relative to future environmental fluctuations.

The Pacific sleeper shark (Somniosus pacificus) is a long-lived, deep-water, sub-polar species that exhibits flexible foraging strategies, likely combining scavenging with active predation on a broad range of prey, yet their role in marine food webs and impact on commercial species remain undetermined. Tracking the location of Pacific sleeper sharks in Alaskan coastal waters is extremely challenging given the predominantly aphotic depths that these sharks occupy, often in spatially constrained and critically under-sampled regions: deep, steep-flanked, convoluted fjords of Prince William Sound (PWS). From the first ever, year-long depth and temperature records recovered from archiving pop-up satellite-linked transmitters (n = 7), we characterized the residence distributions, depth, and thermal habitat for sharks within the PWS fjords and identified seasonal and temporal variation in habitat use. Depths recorded from the seven sharks ranged from 3 to 572 m, and pop-up tag locations suggested a high degree intra-annual residency within western PWS. Ambient water temperatures ranged from 2.65 to 11.1 °C, with little deviation from the median of 5.9 °C. Seasonal patterns emerged within and across individuals relative to the variation in vertical movements, ambient temperatures, and horizontal movements that could reflect resource-oriented strategies. The high degree of residency combined with extensive use of the water column facilitates the use of physically recoverable, high-resolution behavioral and environmental samplers on Pacific sleeper sharks. This adaptive sampling using Pacific sleeper sharks as platforms of opportunity may in turn enable the use of Pacific sleeper sharks as climate and ecosystem sentinels.