Abstract Great blue herons ( Ardea herodias ) represent important ecological indicators within aquatic ecosystems and local population trends may provide insight into ecosystem health. We surveyed heron colonies throughout the tidal reach of the Chesapeake Bay in 2013 to determine status and distribution and to make comparisons to previous (1975–1976, 1985, 1993, 2003) benchmark surveys. We located 423 colonies supporting 15,094 pairs distributed throughout the estuary. Compared to the 1975–1976 benchmark (37 colonies, 3,680 pairs), the number of colonies and estimated population have increased, with an average doubling time of 10.8 and 18.8 years, respectively. The majority of colonies were in supercanopy trees within continuous forests, along forest edges, or on isolated islands or marsh hammocks that provide for crown access. The size of colonies declined over the nearly 40‐year period (β = −0.032 ± 0.004, P < 0.001) with an annual rate of −3.2%. By 2013, <4% of all colonies had >100 pairs compared to 34% in 1985. The fragmentation or abandonment of large colonies and establishment of small colonies appears to be a response to the recovery of bald eagles ( Haliaeetus leucocephalus ). In 2013, most (60%) colonies accounted for <0.1% of the Bay‐wide population. The size distribution of colonies suggests that the equitable threshold between the burden borne by landowners (number of colonies protected) and the benefit to herons (proportion of population protected) lies somewhere between 25 and 50 pairs.
Abstract Artificial light at night (ALAN) has been shown to influence the behavior of migratory birds, yet how different light spectra modulate these effects remains unclear. We conducted a field experiment for 31 nights at a remote site in northern Colorado, USA, using 2 800‐W light‐emitting diode (LED) floodlights with white, red, amber, and blue lighting treatments during fall migration in 2023 and 2024. Using a vertical‐looking radar system, we quantified avian in‐flight responses in migration traffic rate, flight height, and flight direction between paired control periods with no light and periods with lighting treatments. Although we found no effects of our treatments on migration traffic rate and weak effects on flight direction, we found that broad‐spectrum white light with emissions across a 400–600 nm spectrum reduced mean avian flight height by an estimated 22.57 m (±10.53 SE) compared to dark periods, and this response was stronger than red and blue lighting treatments. Our ability to detect behavior changes from a point source in a rural, low‐density migration system supports the notion that the effects of artificial light at night on bird behavior may be more pervasive than is often recognized, and that this varies by ALAN spectra. Beyond providing insight into avian orientation and in‐flight behavior, our results have implications for future research, the conservation management of artificial light at night, and lighting designs that minimize effects on migratory birds.
Abstract Northern bobwhite ( Colinus virginianus ; bobwhite) populations have dramatically declined across their range. These declines are more pronounced in the southeastern United States, where large proportions of agricultural land have been converted to pasture dominated by tall fescue ( Lolium arundinaceum ), an exotic cool‐season grass (CSG) used for grazing and haying that is thought to negatively influence bobwhite survival rates. The use of native warm‐season grass (NWSG) pasture as a working‐lands conservation strategy may benefit bobwhite survival, but data are lacking to test this assertion. We conducted a study in southeastern Kentucky, USA, where grazed CSGs and hayed CSGs were adjacent to grazed NWSGs and burned ungrazed NWSGs. We tracked bobwhites from April 2019 to October 2022 and estimated their survival rates. Bobwhite survival in the breeding season was positively related to an increasing amount of grazed NWSGs (250‐m scale) but only when shrubs (250‐m scale) were highly interspersed. Similarly, survival in the non‐breeding season was positively related to an increasing amount of grazed NWSGs (250‐m scale) but only when shrub interspersion‐juxtaposition (home range scale) was moderate. Results of our study suggest that appropriately grazed NWSG may provide a model for a landsharing approach to bobwhite conservation, but that appropriately distributed shrub cover will be an essential element of this strategy.
Abstract The Ulkatcho people of west‐central British Columbia, Canada, have co‐existed with caribou ( Rangifer tarandus ) since time immemorial, relying on caribou for meat, clothing, tools, and oral history. All 4 caribou herds in Ulkatcho are threatened per the Canadian Species at Risk Act, and the availability of winter habitat is considered a limiting factor in their recovery, with recent wildfires burning much of their critical winter range. We combined traditional ecological knowledge from Ulkatcho Elders with lichen and stand structure measurements at 5 stand‐replacing wildfires to assess the 90‐year recovery of winter caribou habitat. We designed ‘think like a caribou’ methods to capture the recovery of high‐quality forage sites. Bayesian hurdle models fitted to 308 lichen plots found the earliest stand‐level terrestrial caribou lichen recovery at 59 years after fire. The earliest recovery of high‐quality forage sites occurred later at 74 years after fire. Stems per ha of lodgepole pine ( Pinus contorta ) failed to reach suitable openness for caribou within 90 years after fire. Stands were up to 8 times denser than the forest structure of known caribou habitat at the earliest point of lichen recovery. Our findings suggest it takes longer for post‐burn forests in Ulkatcho to reach suitable winter habitat than the general benchmark of 40 years. We posit that the prolonged self‐thinning of lodgepole pine after fire may be a greater limiting factor than lichen abundance for habitat recovery in lodgepole pine forests. Our results demonstrate the importance of adopting a holistic approach towards habitat, one that includes stand structure and lichen abundance alongside Indigenous ecological knowledge.
Abstract Population monitoring of at‐risk species is fundamental to directing effective and timely conservation actions. For wide‐ranging threatened species, such as the wolverine ( Gulo gulo ), monitoring across multiple jurisdictions is necessary to track their distribution to inform collaborative regional and national management and policy. We repeated a landscape‐scale, multi‐jurisdictional remote camera survey first completed in 2017 to evaluate wolverine occupancy throughout the western United States in 2022. Our objectives were to 1) expand the sampling frame to include areas of potential recolonization (Colorado, Oregon, Utah, USA), 2) evaluate whether overall and state‐specific occurrence has changed from 2017 in the common sampling frame of Idaho, Montana, Washington, and Wyoming, USA, and 3) evaluate spatial drivers of wolverine occurrence in 2022. From a sampling frame of 770 sites (15 × 15‐km cells) identified as potential wolverine habitat, 229 sites were surveyed in 2022; no wolverines were detected in Colorado, Oregon, or Utah. We predicted wolverine occupancy and 95% highest posterior density intervals (HPDI) in states with detections to be 0.47 (0.37–0.58) in Idaho, 0.35 (0.21–0.52) in Montana, 0.29 (0.09–0.54) in Washington, and 0.35 (0.27–0.47) in Wyoming. We found weak to moderate evidence of a small decline in overall occupancy () from the common sampling frame (2017: 0.44 [0.37–0.52]; 2022: 0.39 [0.30–0.49]; P() = 0.81), driven by lower occurrences in Montana and Washington. However, this finding is complicated by a change in detection methodology that may have contributed to lower occurrences in Montana and Washington. Lastly, we found strong support (probability of an effect >0.95) that within areas of predicted wolverine habitat, increasing habitat connectivity and the proportion of a site that was previously burned (2001–2015) were associated with increased wolverine occupancy, while increasing normalized difference vegetation index (NDVI) was associated with decreased wolverine occupancy. Our expanded sampling frame provides the means to track wolverine occupancy and range extent—including recolonizations and contractions—across the western United States, providing insights at both the state and national scales.
Abstract Management of white‐tailed deer ( Odocoileus virginianus ) to control their consumptive effects on understory forest vegetation has been a long‐standing challenge in Pennsylvania, USA. In 2003, the Pennsylvania Game Commission implemented the Deer Management Assistance Program (DMAP) to allow landowners to increase antlerless harvest in localized areas, which has been used by the Pennsylvania Department of Conservation and Natural Resources (DCNR) on state forest lands. We evaluated survey data describing hunter participation and satisfaction over 2 periods (2013–2015 and 2019–2021) and across 4 DMAP areas on state forest lands managed by DCNR. Two study sites had greater DMAP permit allocations (1 permit per 6 ha) to attempt to reduce deer density compared to 2 other study sites (1 permit per 20 ha). Prior to 2020, only DMAP permits could be used to harvest antlerless deer during the first week of the firearm hunting season. In 2020, regulation changes allowed both DMAP and wildlife management unit antlerless licenses to be used throughout the firearm hunting season and DMAP permit allocations continued to be sold out only in areas where most hunters lived >80 km from the DMAP area. Satisfaction increased between periods, with hunters twice as likely to be satisfied during 2019–2021; however, increased satisfaction may be partly explained by dissatisfied hunters dropping out, as >50% of hunters purchased a single DMAP permit in 6 years, and only 20% of hunters purchased ≥1 permit in both periods. The strongest positive predictors of satisfaction were seeing an antlerless deer, harvesting an antlerless deer, and repeated participation through purchasing multiple DMAP permits. Consequently, understanding why few hunters are consistent purchasers of DMAP permits may provide insights into how landowner permit allocation or other currently unknown factors influence participation in the DMAP or similar programs encouraging harvest of antlerless deer.
Abstract Common ravens ( Corvus corax ; ravens) are generalist avian predators whose populations have rapidly increased across North America, concomitant with anthropogenic development. Raven populations are bolstered by anthropogenic food and nesting resources in areas outside of their historical range and are impactful predators for many prey species of conservation concern, including greater sage‐grouse ( Centrocercus urophasianus ; sage‐grouse), primarily through reductions in sage‐grouse nest survival. Previous research suggests that coating developing raven eggs in non‐toxic oil, a form of egg‐addling, positively affects sensitive prey species because the nesting ravens no longer need to provision for young, and thereby forage less. We sought to understand the effects of oiling raven eggs on raven population density and reproductive success, as well as nest survival and population growth rate of co‐occurring populations of sage‐grouse. By evaluating oil‐treated, control, and sham‐treated (applied water rather than oil) raven nests in a before‐after‐control‐impact (BACI) research study design, we found that application of oil to raven eggs reduced raven egg hatchability by 94.5% and reduced raven densities at treatment sites relative to control sites. Sage‐grouse nest survival probabilities more than doubled at egg‐oiled treatment sites, resulting in a relative increase of 93.0% at treatment sites relative to control sites over the same period of inference. Finally, estimated abundances of sage‐grouse increased at oil‐treated sites by 44% relative to controls following oil treatments of raven eggs, also measured in a BACI framework. Oiling of raven eggs had strong and immediate impacts on co‐occurring populations of sage‐grouse and ravens.
Abstract Opportunities to observe local wildlife can foster well‑being, ecological literacy, and pro‑conservation attitudes. Correct species identification is critical to achieving these outcomes. I documented a case of cross‑family misidentification in an urban residential area of Uji City, Kyoto, Japan, based on a photograph shared through a community circular. A native, endemic Japanese badger ( Meles anakuma ) was misidentified as a native raccoon dog ( Nyctereutes procyonoides ). The circular further included information on the non‑native raccoon ( Procyon lotor ), compounding confusion. This error misdirected residents' perceptions and recommended actions, producing a false negative for Japanese badger presence in local knowledge. Even a single well‐communicated misidentification can influence biodiversity records, legal framing, and conservation messaging. Addressing such errors offers an opportunity to improve public recognition of regionally important species and strengthen human–wildlife relationships in urban landscapes.
Abstract We used a published individual‐based model to evaluate localized deer removal strategies for managing chronic wasting disease (CWD) in a free‐ranging white‐tailed deer population in central Michigan, USA. We simulated fine‐scale (23.3 km 2 ) deer culling using ring, land parcel‐based, and habitat quality‐based removal methods. Ring culling consisted of highly concentrated culling in a focal area (e.g., CWD detection area), with effort diminishing as distance away from that location increased. Land parcel‐based culling represented a scenario where land access permissions varied across space. Habitat quality‐based culling represented intense culling in areas thought to be high‐quality deer habitat (thereby likely containing more targets). We also assessed male‐targeted strategies for ring and parcel‐based methods. We used cost estimates from 2016–2021 in Michigan to calculate total annual localized deer culling expenditures for each removal method. Lastly, we investigated how local conditions, including initial deer density and study area context, affected management outcomes. Chronic wasting disease was less likely to persist in our projections, and prevalence rate was lower, for deer inhabiting a suburban study area compared to an exurban area. All culling methods reduced the probability that CWD would persist and lowered 15‐year prevalence in the population compared to no culling. Ring culling near the site of detection (1.6‐km instead of 2.4‐km radii ring) was most effective at minimizing CWD persistence at medium and high deer densities. However, the ring size most effective at reducing 15‐year CWD prevalence depended on study area context and deer densities, with the 2.4‐km cull resulting in the lowest prevalence at medium and high deer densities in the suburban study area. At low deer density, parcel‐based culling performed best in both study area contexts. Targeting male deer only was consistently less effective at reducing CWD persistence and prevalence and more costly than non‐selective deer culling. All culling methods that did not target males had similar total costs for one year of culling in the 23.3‐km 2 area, but costs varied considerably based on study area ($5,500–22,100 USD) and deer density ($14,300–25,700). Our model simulations indicated that male‐focused culling strategies are less effective and more expensive than non‐selective strategies, that ring‐based culling is most effective at medium and high deer densities, and that CWD persistence and prevalence in exurban locales are greater compared to suburban locales, regardless of culling strategy.
Advances in consumer electronics and the increasing availability of spatially explicit data are driving a revolution in tracking animal movement. Free-ranging avian, terrestrial, and marine species are now tracked at fine spatial and temporal resolutions, revealing useful insights into their ecology. However, miniaturized tracking devices are rarely attached to medium and large terrestrial mammals, with researchers deploying collars on most larger species. We deployed 6 prototype solar-powered, global navigation satellite system (GNSS) tracking devices on 2 endangered large terrestrial mammals-scimitar-horned oryx (Oryx dammah) and Przewalski's horse (Equus ferus przewalski)-with devices attached to horns and tails, respectively. We assessed device performance as well as potential physiological and behavioral effects of these alternative attachments of tracking devices. Novel attachment methods achieved fix success rates of 31-100% (mean = 77%) and spatial accuracy (11-36 m) that compare well with standard collar attachments used on large terrestrial mammals (fix success: 29-100%, mean = 69%; spatial accuracy: 10-40 m). In generalized additive models, the presence of a device did not significantly predict behavioral or physiological stress for either species. Solar panels were able to maintain charge throughout the test period. However, deployment lifespan (mean = 55 days for horses and 26 days for oryx) was ultimately limited by attachment method. While a later modification substantially improved deployment length, attachment durability remains a key area for improvement. We urge ecologists and conservation practitioners to consider the full range of tracking devices and attachment methods available from tracking technology manufacturers, assess whether alternative attachments could achieve scientific or conservation objectives with reduced impacts on study species, and carefully test any tracking device before long-term deployment.
Bobcats (Lynx rufus) are an abundant and widely studied carnivore of ecological and management importance; however, factors like spatiotemporal variation in survival rates make it difficult to identify primary drivers of survival among studies. We used meta-analysis techniques to synthesize bobcat survival rates across their geographic range and elucidate factors driving variation among estimates. We performed a literature search for annual bobcat survival rates that were estimated using radio-collar data and obtained 19 of them across 16 states in the United States from 1983-2019. Using a mixed-effects model where the effect size was a study's reported survival rate, we evaluated the effects of year, sample size, study length, and analysis type in a meta-regression framework to examine whether these covariates could explain heterogeneity among survival rates. Additionally, we tested for potential spatial effects on survival rates (i.e., latitude, longitude, region, mean annual harvest, and harvest status), which could be driven by factors such as harvest interest, hunter effort, and pelt prices. Mean annual bobcat survival across studies was 0.75 (95% CI = 0.69-0.80). Study year explained 26.4% of heterogeneity (P = 0.031) and indicated that survival rates increased from 1983-2019. Additionally, sample size explained 32.5% of heterogeneity (P = 0.024) and indicated that survival rates increased with increasing sample sizes. Increasing survival rates through time may be attributed to conservation practices, improved monitoring of radio-collared animals, or a combination of biological and methodological changes. More than half of the between-study heterogeneity was explained by the population's exploitation level (R 2 = 61.7%, P = 0.003) and suggested that nuance in site-level harvest restrictions (e.g., permitted vs. restricted areas for harvest) influenced survival rates. We recommend evaluation of bobcat harvest policies and consistent inclusion of explicit details regarding harvest regulations (e.g., bag limits, number of tags issued, season length, proportion of land where harvest is permitted) to help clarify the link between harvest and survival in future studies.
Fire is a major force that can shape mammal activity patterns and predator-prey dynamics. We used camera trap data to investigate changes in temporal activity patterns of felid top predators such as jaguars (Panthera onca), pumas (Puma concolor), and their prey following fire events in the Brazilian Pantanal. Using kernel density estimation, we compared activity patterns between pre-fire (2011-2013) and post-fire (2020-2022) periods for 8 mammal species. We analyzed 3,824 detections (pre-fire = 1,596; post-fire = 2,228) across 6 prey species and 2 predator species. Our analysis revealed that 5 of 6 prey species and both predator species showed statistically significant changes in temporal activity patterns following fire (Watson's U-2 test, P < 0.05). Most species shifted toward earlier activity, with an average temporal displacement of -1.82 hours for prey species and -1.65 hours for predators. Temporal overlap between predators and prey decreased by an average of 4.8% post-fire, suggesting potential disruption of predator-prey synchronization. Lowland tapir (Tapirus terrestris) was the only species without strong evidence for temporal change (P > 0.05), demonstrating behavioral resilience. In contrast, collared peccary (Dicotyles tajacu) exhibited the most drastic response with a -4.18-hour shift in activity timing. These findings demonstrate fire-induced behavioral plasticity in Neotropical mammals and provide a foundation for targeted conservation strategies, such as securing unburned refugia for sensitive species and timing restoration activities to accommodate altered activity patterns.
