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Understanding how landscape change influences the distribution and densities of species, and the consequences of these changes, is a central question in modern ecology. The distribution of white-tailed deer (Odocoileus virginianus) is expanding across North America, and in some areas, this pattern has led to an increase in predators and consequently higher predation rates on woodland caribou (Rangifer tarandus caribou)—an alternate prey species that is declining across western Canada. Understanding the factors influencing deer distribution has therefore become important for effective conservation of caribou in Canada. Changing climate and anthropogenic landscape alteration are hypothesized to facilitate white-tailed deer expansion. Yet, climate and habitat alteration are spatiotemporally correlated, making these factors difficult to isolate. Our study evaluates the relative effects of snow conditions and human-modified habitat (habitat alteration) across space on white-tailed deer presence and relative density. We modeled deer response to snow depth and anthropogenic habitat alteration across a large latitudinal gradient (49° to 60°) in Alberta, Canada, using motion-sensitive camera data collected in winter and spring from 2015 to 2019. Deer distribution in winter and spring were best explained by models including both snow depth and habitat alteration. Sites with shallower snow had higher deer presence regardless of latitude. Increased habitat alteration increased deer presence in the northern portion of the study area only. Winter deer density was best explained by snow depth only, whereas spring density was best explained by both habitat alteration and the previous winter’s snow depth. Our results suggest that limiting future habitat alteration or restoring habitat can alter deer distribution, thereby potentially slowing or reversing expansion, but that climate plays a significant role beyond what managers can influence.

Anthropogenic habitat alteration is a threat to biodiversity globally. Challenges to conservation are often related to lack of data and public awareness of conservation importance. In terrestrial conservation, these challenges have predominately been addressed using surrogate species. This includes umbrella species, whose ecological needs are known and encompass the needs of many other species that depend on the same habitats. Lack of public support for conservation has been addressed using flagship species, which are selected based on non-biological characteristics to promote public awareness of conservation needs and increase support for habitat conservation. Mangroves are the most threatened coastal habitats. Here, we test the hypothesis that the fish common snook (Centropomus undecimalis), an obligate user of mangrove creeks and other transitional coastal habitats as juveniles, is an appropriate umbrella species for habitat conservation. We examined data spanning 16 years across 27 mangrove creeks and show that protecting habitat use by juvenile snook protects an ecologically important fish assemblage of more than 55 native species, further adding value to mangrove habitats. In addition, because snook support an economically important recreational fishery with a high public profile comprised of fishers with increasing interests in conservation, snook is also an appropriate flagship species that will help leverage collaboration between the recreational fishery stakeholders and the agencies tasked with fishery management.

Understanding an organism's habitat selection and behavioural flexibility in the face of environmental change can help managers plan for future conservation of that species. Hyperabundant tundra‐nesting geese are influencing Arctic environments through their foraging activities. Goose‐induced habitat change in Arctic wetlands may influence the availability of habitat for numerous shorebird species that breed sympatrically with geese. We explore whether goose‐induced habitat alteration affects shorebird breeding density and nest site selection. Using habitat data collected at sites with High, Moderate and Low goose influence, and samples collected during two periods separated by 11 years, we document the habitat characteristics influenced by geese. We describe the habitat characteristics preferred by shorebirds and relate their availability to goose influence and shorebird density. Finally, we examine whether shorebird nest site selection has changed over time and whether shorebirds select nest sites differently in habitat influenced by geese. We document spatial and temporal changes in sedge meadow habitat and lateral concealment relating to goose influence. The availability of sedge meadow habitat and the degree of lateral concealment declined with increasing goose influence, and also declined at two sites over the 11 years of the study. Densities of both cover‐ and open‐nesting shorebirds were highest where goose influence was lowest. At sites with Low goose influence, cover‐nesting shorebirds selected nest sites with more sedge meadow and concealment than at sites with Moderate and High goose influence, presumably because these high‐quality sites were more available. Synthesis and applications. Intensive foraging by a colony of hyperabundant geese is limiting the availability of preferred nesting habitat and densities of sympatric‐nesting shorebirds. Where goose‐induced habitat alteration is pronounced shorebird species that select concealed nest sites are nesting in areas with lower concealment and less sedge meadow. Studies examining the degree to which these effects scale up to impact the population sizes of declining shorebirds should be considered a future research priority. Moreover, management strategies for geese should incorporate the habitat needs of sympatric species and reinvigorate efforts for goose population reduction in order to achieve the population targets articulated by management agencies. Intensive foraging by a colony of hyperabundant geese is limiting the availability of preferred nesting habitat and densities of sympatric‐nesting shorebirds. Where goose‐induced habitat alteration is pronounced shorebird species that select concealed nest sites are nesting in areas with lower concealment and less sedge meadow. Studies examining the degree to which these effects scale up to impact the population sizes of declining shorebirds should be considered a future research priority. Moreover, management strategies for geese should incorporate the habitat needs of sympatric species and reinvigorate efforts for goose population reduction in order to achieve the population targets articulated by management agencies.

Abstract Theoretical, field-based, and experimental research all suggest that animal populations remain relatively stable under increasing habitat alteration until a critical threshold is reached, after which small changes to habitats result in large negative responses. However, there are few empirical examples demonstrating this in marine fishes, making identification of such thresholds difficult. Here, we synthesized long-term (25 + year) fisheries and habitat datasets across four estuaries in Florida (USA) to examine the combined effects of a once in ninety-year cold spell and habitat alterations on populations of an estuarine dependent fish, common snook (Centropomus undecimalis). In Florida, common snook support an important recreational fishery where harvest is well-managed. Common snook populations in three estuaries with less severe habitat alterations recovered to pre-disturbance levels within 4 years of the cold spell. However, in the estuary with the most extensive habitat alteration—including 34% loss of mangrove habitats, near complete loss or fragmentation of saltmarsh habitats, a 65,000 acre seagrass die-off, and eutrophication—the common snook population had yet to recover 8 years after the cold spell. Using a life-stage explicit approach, habitat alterations affecting early life history processes (i.e., juvenile survival and larval settlement) may be responsible for decreased resilience. This study highlights the need for fisheries management to consider habitat loss and disturbance, along with harvest in stock assessment and management processes. Adopting policies to protect and restore habitats will improve fish population resiliency to disturbance, thereby mitigating non-linear and costly declines to fisheries.

Changes to the environment often affect animal behavior at the individual and group levels. For aquatic species, disturbances such as heavy rains and runoff may create a highly turbid (i.e., cloudy or visually obscured) environment, which potentially may affect individual interactions and group coordination. Surprisingly, we know little about how decreases in water clarity may influence important collective behavior, such as shoaling in fishes. We hypothesize that differences in water clarity would alter collective movement in fishes. We used an automated video tracking software to collect and process continuous, high-resolution spatial data in both clear and turbid waters. We studied two species of fishes that rely on vision for shoaling, the red shiner (Cyprinella lutrensis) and the sand shiner (Notropis stramineus). For each species, we used 20 groups of five fish each in a mixed-model design with three turbidity treatments: 0, 50–150, and 200–300 nephelometric turbidity units (NTUs). There were species-specific differences, but the patterns of response to turbidity were similar. Both species experienced decreased collective behavior in response to turbidity as indicated by significant increases in interfish distances and shoaling area as well as decreases in velocity. These findings show that turbidity may significantly influence collective behavior and group structure and are consistent with (but not conclusively so) a sensory limitation causation. We also provide basic knowledge in an area that is understudied and may be useful for conservation and management objectives, especially at a time when so many fishes are threatened due to habitat degradation and alteration.

Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most threatened plant families, yet the impact of invasive bees on their reproduction remains poorly understood. We conduct a global literature survey on the incidence of invasive honeybees ( Apis mellifera ) on orchid pollination, followed by a study case on Australian orchids. Our literature survey shows that Apis mellifera is the primary alien bee visiting orchids worldwide. However, in most cases, introduced honeybees do not deposit orchid pollen. We also test the extent to which introduced honeybees affect orchid pollination using Diuris brumalis and D. magnifica . Diuris brumalis shows higher fruit set and pollination in habitats with both native and invasive bees compared to habitats with only introduced bees. Male and female reproductive success in D. magnifica increases with native bee abundance, while conversely pollinator efficiency decreases with honeybee abundance and rises with habitat size. Our results suggest that introduced honeybees are likely involved in pollen removal but do not effectively deposit orchid pollen, acting as pollen wasters. However, Apis mellifera may still contribute to pollination of Diuris where native bees no longer exist. Given the global occurrence of introduced honeybees, we warn that certain orchids may suffer from pollen depletion by these invaders, especially in altered habitats with compromised pollination communities.

As humans continue to alter natural habitats, many wild animals are facing novel suites of environmental stimuli. These changes, including increased human–wildlife interactions, may exert sublethal impacts on wildlife such as alterations in stress physiology and behavior. California ground squirrels (Otospermophilus beecheyi) occur in human-modified as well as more pristine environments, where they face a variety of anthropogenic and naturally occurring threats. This makes this species a valuable model for examining the effects of diverse challenges on the physiology and behavior of free-living mammals. To explore potential sublethal effects of habitat modification on O. beecheyi, we compared body masses, behaviors, and fecal glucocorticoid metabolite (FGM) levels for free-living squirrels in human-disturbed versus undisturbed habitats. Prior to these analyses, we validated the use of FGMs in this species by exposing captive O. beecheyi to pharmacological and handling challenges; both challenges produced significant increases in FGMs in the study animals. While FGM responses were repeatable within captive individuals, responses by free-living animals were more variable, perhaps reflecting a greater range of life-history traits and environmental conditions within natural populations of squirrels. Animals from our human-disturbed study site had significantly higher FGMs, significantly lower body masses, and were significantly less behaviorally reactive to humans than those from our more pristine study site. Thus, despite frequent exposure of California ground squirrels to human impacts, anthropogenic stressors appear to influence stress physiology and other phenotypic traits in this species. These findings suggest that even human-tolerant mammalian species may experience important sublethal consequences due to human modifications of natural habitats.

Dominant, habitat-forming plant species, such as seagrasses, are key components of coastal ecosystems worldwide. Multiple stressors, including invasive species that directly alter, remove, or replace the foundation plant species, threaten these ecosystems. On the Atlantic coast of North America, ecosystem engineering by invasive European green crab (Carcinus maenas) has been linked to the loss of some eelgrass (Zostera marina) beds. However, the interaction of the same co-occurring species on the Pacific coast has not been investigated. We conducted an enclosure experiment in Barkley Sound, British Columbia, to determine if the engineering impacts of green crabs on Pacific eelgrass ecosystems mirror those previously identified on the Atlantic coast. Eelgrass shoot density declined rapidly over 4 weeks, with a 73–81% greater loss in enclosures with high crab density compared to the low-density and control treatments. The low ratio of eelgrass blades to rhizomes in the high-density treatment suggests that blade shredding, rather than bioturbation of whole plants, was the main mechanism of eelgrass loss. Eelgrass was detected in green crab stomach contents, consistent with observations from the Atlantic coast. Crab density did not have a detectable effect on the biomass or community composition of benthic fauna associated with eelgrass over the duration of the experiment. The eelgrass loss we observed was consistent with losses observed on the Atlantic coast, which raises management concerns on the Pacific coast, particularly in areas where green crabs co-occur with other coastal stressors and with ecologically and economically important species such as salmon.

In rapidly changing environments, assessing the degree to which animals behaviorally respond to human disturbance can help identify activities of concern or populations at risk. We examined circadian activity patterns of bobcats (Lynx rufus), coyotes (Canis latrans), mule deer (Odocoileus hemionus), elk (Cervus canadensis), lagomorphs, and rodents during crepuscular, day, and night periods using data captured from 40 remote cameras distributed across a 162-km2 area with starkly different levels of current and historical energy development. During the winter of 2015–2016, we obtained 3,067 independent detections from 7,185 camera days of our 6 target species. In mixed support of our hypotheses, bobcats, coyotes, and mule deer were less active during the day in the developed site compared to the undeveloped site, as were rodents, which was unexpected. In contrast, elk and lagomorphs did not show differences across sites. Bobcats demonstrated the greatest reduction in diurnal activity, with nearly 3 times less activity in the developed site. Coyotes and mule deer appeared to compensate for reduced activity during the day by increasing their activity during other periods, though bobcats did not. The mammal species captured in this study demonstrated strong differences in their plasticity and sensitivity to energy development approximately 4 years post high-intensity disturbance, which likely influences their susceptibility to human-driven landscape changes.

Non-native species introduced into reservoirs cause major changes in biodiversity, resulting in spatial and temporal biotic homogenization and/or differentiation. We used a sampling standardized temporally and spatially in reservoirs of basins located in the Neotropics, the Coastal, Iguaçu, and Upper Paraná basins. Our analyses were conducted at the interbasin and intrabasin scales, aimed at: (i) identifying the non-native species and their major vectors of introductions, (ii) assessing temporal and spatial changes in the fish assemblages, and (iii) evaluating temporal changes in the beta diversity of the basins/reservoirs. The spatial occupation of non-native species was variable, with Tilapia rendalli, Cyprinus carpio and Oreochromis niloticus the most frequently introduced species. This highlights aquaculture as the main vector of invasives on a large spatial scale. The percentage of non-native species at the interbasin and intrabasin scales increased over time. Temporal comparisons of the fishes support the hypothesis that biotic homogenization occurred at the interbasin scale, whereas the biotic differentiation was observed at the intrabasin scale. Beta diversity decreased over time at the interbasin and intrabasin scales, with decrease in species richness serving as the variable that best explained changes in biological diversity. There was no relation between beta diversity and time for the Iguaçu.