Extreme weather events, such as tropical storms, can pose profound disruption to nearshore marine environments. Although coastal ecosystems are particularly vulnerable to storm impacts, research describing the response of marine taxa to extreme weather remains limited, especially for highly mobile marine predators. In this study, we use acoustic telemetry to investigate the behavioral responses of juvenile white sharks (Carcharodon carcharias) at a Southern California nursery aggregation site to Tropical Storm Hilary in 2023. To aid in these efforts, we developed a novel occupancy modeling approach to statistically account and correct for temporal variations in acoustic receiver performance during disruptive storm conditions. Using detection data from synchronization transmitters, we first estimated the effects of key environmental factors on transmitter detection efficiency, with ambient noise, receiver tilt, and the density of animal transmitters present inside the receiver array emerging as particularly influential predictors. We then leveraged these estimated effects to inform a Bayesian state space model designed to investigate nursery occupancy dynamics, including environmental drivers of nursery emigration. Our results provide evidence of partial nursery evacuation, with over half of tagged sharks temporarily leaving monitored nearshore habitats in response to peak storm conditions. However, most emigrations were short-lived, with all but one shark returning to the aggregation site within three weeks of the storm. Evacuations from nursery habitats were best predicted by falling sea surface temperatures, although increased wave height, declining barometric pressure, and drops in salinity may have served as important secondary flight cues. Our efforts provide a rare opportunity to document the storm response behaviors of a recovering top predator, while also presenting tangible analytical solutions to commonly encountered technical challenges in the field of acoustic telemetry.

The conservation of tropical biodiversity will require not only protected areas, but also strategies to retain animals in degraded secondary forests and countryside agricultural landscapes. This study aims to identify key landscape elements and land-use types that support the movement of mixed-species bird flocks in areas outside, but adjacent to, rainforests in lowland Sri Lanka. We recorded flock movement pathways at five sites using handheld GPS, and documented flock composition, land-use, and habitat variables at waypoints every 15min. Land cover was assessed through high-resolution satellite images, and classified into land-use categories based on dominant vegetation. To analyze habitat selection, we employed a resource selection function using generalized linear mixed models. A total of 112 flocks were observed, yielding 754 location records (average 7 ± 3 [SD] points per flock) across ten 3-km transects over two years. Overall, a diverse array of species (n = 66) was recorded in flocks. An interaction between land-use and time of day affected flock habitat selection, with preference for water-associated habitat such as marsh and riparian corridors, and mixed cultivation, particularly high after morning, while tea plantations were generally avoided throughout the day. Flock speed was inversely related with land-use preference, and increased when the leading species Orange-Billed Babbler (Argya rufescens) was present. Flock size and species richness strongly declined with increasing distance to the forest, with the exception that marsh, riparian corridors and mixed cultivation retained large flocks. The findings emphasize how mixed-species flocks can move through human modified landscapes and how their organization (e.g., leading species) influences that process. To sustain avian diversity in agroecosystems, conservation strategies must be spatiotemporally explicit. The study highlights the importance of planning heterogeneous landscapes, including water-associated habitat and mixed cultivations, in order for flocks to persist in this agricultural landscape.

As human activity increases worldwide, many ecologists have focused on how anthropogenic linear features (ALFs) such as roads and fences impact and disrupt animal space-use behavior and how this disruption could potentially affect population viability. The properties of an animal's occurrence distribution (OD), namely its size, shape, and habitat associations, reflect the animal's balance of costs and benefits and thus can act as indirect indicators of behavioral optimality. Measuring deviations from theoretical space-use optimality can provide insight into the non-lethal effects of ALFs on wildlife in different environmental contexts. Here, we focused on the seasonal space-use patterns of two wide-ranging, highly mobile species of great cultural and economic value: mule deer (Odocoileus hemionus; n = 3105) and pronghorn (Antilocapra americana; n = 320). We calculated the average use of six environmental and three ALF attributes, weighted by their intensity of use within the OD, and contrasted those with their respective average availability within a 100-km2 reference area centered on each animal's OD. We show that mule deer space-use is more impacted by roads, while pronghorn space-use is affected more by fences, specifically in the winter when snow depth may hinder their ability to cross fences. Our results highlight the dynamic nature of the availability domain and the importance of properly accounting for this dynamism in habitat selection analyses. This research expands on the theoretical literature of animal space use and their response to ALFs in a rapidly changing world and further provides practical strategies for wildlife managers to take when mitigating ALF impacts on their target species.

Prey species need to adjust their habitat selection either temporally or spatially to reduce predation risk or human disturbance. We tested the risk allocation hypothesis that poses that foraging is higher in low-risk habitats and during low-risk periods for impala (Aepyceros melampus) in the Serengeti Ecosystem. We expected impalas to select ranges that balance long-term predation risk and forage availability and adjust their habitat utilization within their ranges temporally to balance short-term predation risk and energy intake. We modelled multi-scale resource selection for 36 GPS-tracked impala (2016-2018) to disentangle spatial and temporal trade-offs between forage acquisition and predation risk using resource selection functions at the landscape and within-home-range level. We contrasted resource selection inside and outside of Serengeti NP (SNP) for woody cover, forage availability (vegetation heterogeneity, NDVI) and risky places (proximity to water, terrain ruggedness). We also modelled responses to diel and lunar cycles in space use. Impalas attuned their resource selection both towards maximizing forage availability and minimizing risk exposure, especially at the landscape level. While home-ranges were generally placed in more homogeneous woodland close to water sources, impalas preferred to use more heterogeneous, open and rugged patches within their home-ranges. They adjusted their responses outside SNP by placing their home-ranges in less rugged terrain and farther from water sources. Impalas balanced foraging and risk temporally by adjusting their preferences to circalunar and diel patterns. Impala attuned their home-range placement and utilization according to the 'landscape of fear' hypothesis inhabiting a 'squeezed' landscape. Here, prey to a functionally diverse carnivore guild clearly balanced their space use between food acquisition and spatio-temporal risk avoidance. Humans, however, acted as a 'super-predator' eliciting a stronger behavioural response compared to natural predators. Following the risk allocation hypothesis, the presence of humans was of such an intensity and predictability that it changed the anti-predator responses in impala compared to the adjacent natural system with carnivores only. A functional response in habitat selection indicated that impala avoided long-term spatial risk in home-range placement, while within their home-ranges short-term temporal risk mimicked the diel patterns observed within the protected area with natural predators only.