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Animals may select habitat to maximize the benefits of foraging on growth and reproduction, while balancing competing factors like the risk of predation or mortality from other sources. Variation in the distribution of food resources may lead animals to forage at times or in places that carry greater predation risk, with individuals in poor quality habitats expected to take greater risks while foraging. We studied Mojave desert tortoises (Gopherus agassizii) in habitats with variable forage availability to determine if risk aversion in their selection of habitat relative was related to abundance of forage. As a measure of risk, we examined tortoise surface activity and mortality. We also compared tortoise body size and body condition between habitats with ample forage plants and those with less forage plants. Tortoises from low forage habitats selected areas where more annual plants were nutritious herbaceous flowering plants but did not favor areas of greater perennial shrub cover that could shelter them or their burrows. In contrast, tortoises occupying high forage habitats showed no preference for forage characteristics, but used burrows associated with more abundant and larger perennial shrubs. Tortoises in high forage habitats were larger and active above ground more often but did not have better body condition. Mortality was four times higher for females occupying low forage habitat than those in high forage habitat. Our results are consistent with the idea that tortoises may minimize mortality risk where food resources are high, but may accept some tradeoff of greater mortality risk in order to forage optimally when food resources are limiting.

The economically and ecologically catastrophic introduction of invasive brown treesnakes to the Pacific Island of Guam has long served as a cautionary tale about the dangers of invasive species and the seeming impossibility of their management on a landscape scale. USDA Wildlife Services and federal and private partners have engineered a system for the automated manufacture and aerial delivery of toxic baits for landscape-scale suppression of brown treesnakes in large and remote forest plots. The helicopter-borne dispensing module can launch four bait cartridges per second, and a single payload of 3,600 cartridges can treat 30 ha of forest at 120 baits/ha in 15 to 30 minutes depending on flightpath efficiency. In this paper we recap the research, development, testing, and implementation of the system, including the procedures for monitoring biological responses to bait applications during an experimental suppression within a 55-ha forest plot surrounded by a snake-proof barrier.

Gape‐limited predators (e.g., snakes, many fish) are not generally expected to pose a predation threat to prey that are too large for them to swallow. However, the extent to which snakes predate on prey that exceed their gape limitation remains largely unknown. We conducted the first study to investigate the influence of both prey and predator sizes on the frequency of ingestion success by snakes in a natural system. We combined survival monitoring of an avian prey species (Aplonis opaca) via radio‐telemetry with a survey of the size distribution of their major predator (Boiga irregularis) on Guam. This allowed us to assess (1) the frequency of unsuccessful ingestion by the predator, (2) whether the size of the prey predicts ingestion success, (3) whether the size of the predator predicts ingestion success, and (4) the relationship between prey and predator sizes in successful ingestion attempts. We found that nearly half (47.95%) of ingestion attempts by snakes on fledgling birds were unsuccessful, and no instances where unsuccessful ingestion caused the mortality of the snake. Attempts to consume smaller fledglings were as likely to be unsuccessful as attempts to swallow larger fledglings. However, snakes that successfully ingested fledglings were among the largest snakes in the population, and larger than average conspecifics attracted to endothermic prey. The smallest snakes that successfully ingested fledglings attained remarkably high relative prey mass values for their species, consuming prey weighing up to 79.9% of their own mass. Our study indicates that B. irregularis routinely predate prey that are too large for them to successfully ingest, which causes mortality to the prey but poses little risk to the predator. The potential reward for snakes in consuming oversized prey may outweigh the inherent risks, while instances of predation that do not result in consumption may have considerable impacts on prey populations. [ABSTRACT FROM AUTHOR]

Growing pressure to develop public lands for renewable energy production places several protected species at increased risk of habitat loss. One example is the Mojave desert tortoise (Gopherus agassizii), a species often at the center of conflicts over public land development. For this species and others on public lands, a better understanding of their habitat needs can help minimize negative impacts and facilitate protection or restoration of habitat. We used radio-telemetry to track 46 neonate and juvenile tortoises in the Eastern Mojave Desert, California, USA, to quantify habitat at tortoise locations and paired random points to assess habitat selection. Tortoise locations near burrows were more likely to be under canopy cover and had greater coverage of perennial plants (especially creosote [Larrea tridentata]), more coverage by washes, a greater number of small-mammal burrows, and fewer white bursage (Ambrosia dumosa) than random points. Active tortoise locations away from burrows were closer to washes and perennial plants than were random points. Our results can help planners locate juvenile tortoises and avoid impacts to habitat critical for this life stage. Additionally, our results provide targets for habitat protection and restoration and suggest that diverse and abundant small-mammal populations and the availability of creosote bush are vital for juvenile desert tortoises in the Eastern Mojave Desert.

Context Roads are a pernicious form of habitat loss for many wildlife populations because their effects often extend far beyond the roads themselves, giving rise to reduced wildlife abundance in road-effect zones. Quantifying the extent of road-effect zones more accurately portrays their impact on populations and the true extent to which habitat is lost for many species. Aim The purpose of the present study was to evaluate ways of determining the extent of road-effect zones for a model study species to better quantify the effect of roads on habitat loss. Methods We conducted road-side surveys for signs of Mojave desert tortoises (Gopherus agassizii) 0, 200, 400, 800 and 1600m from county roads and interstates, two of the most common road types in critical habitat of this threatened species. Using data from these road-side surveys, we estimated the extent of road-effect zones using piecewise regression and modified von Bertalanffy models. Key results We found reduced abundances of tortoise sign along both county roads and interstates. Reductions extended farther from the large, high-traffic interstate than from the smaller, lower-traffic county roads (306m versus 230m). The increase in the abundance of tortoise signs with distance from roads approximated a negative exponential curve. Conclusions Interstate and county roads both contribute to habitat loss in road-side areas by making these habitats unsuitable to desert tortoises, presumably by removing animals via mortality from collisions with vehicles. Larger roads with greater traffic have more extensive effects. Implications Roadside mitigation fencing has been proposed as one way to reduce mortality of desert tortoises and to reclaim habitat by allowing tortoises to recolonise currently depauperate road-effect zones. Immediate mortality is more likely to be prevented by fencing county roads where tortoises occur closer to roads and are more likely to be struck by vehicles and killed. However, fencing interstate should yield more reclaimed habitat than that obtained from fencing county roads. Managers must consider balancing these goals along with other concerns when deciding where to place roadside fencing.

Camouflage via animal coloration and patterning is a broadly important antipredator strategy. Behavioral decision making is an influential facet of many camouflage strategies; fitness benefits often are not realized unless an organism selects suitable backgrounds. Controlled experimental studies of behavioral strategies in selection of backgrounds conferring camouflage, however, are rarely paired with observations of wild populations. In order to investigate how substrate composition influenced habitat preference and selection by juvenile desert tortoises (Gopherus agassizii), we completed a manipulative experiment in captivity and an observational study in the wild. In our captive experiment, we found that tortoises spent a greater portion of their time near rocks. We similarly found that wild tortoises preferentially placed themselves in areas with equivalent or larger-sized rocks. Additionally, juvenile tortoises were found to be less detectable on rock substrate by observers than they were on substrate-lacking rocks. We hypothesize that rocks improve juvenile tortoise camouflage and thus that tortoises select for habitat containing rock substrate, in part, due to a survival advantage conferred by such use. The desert tortoise is a threatened species, and the present study provides a model for examining the intersection between behavior and conservation, with implications for how suitable habitat is defined and measured in species conservation programs.

Natural resource management often co‐occurs with considerable uncertainty. One approach to mitigating uncertainty is through adaptive resource management (ARM), a specialized form of structured decision‐making that modifies management decisions or actions through monitoring and implementation.Here, we present a case study on the attempted eradication of an invasive brown treesnake (Boiga irregularis) in a 5‐ha enclosure on Guam with uncertainty in approach. We applied an ARM process across three field phases of snake removal and evaluated whether (1) eradication was achievable and (2) eradication was necessary to achieve an avian response. Field phases included the application of aerial toxic baits, toxicant baiting large mouse and birds, trapping with live mouse and bird lures and hand capture.We found that each removal technique improved control by either removing many individuals or targeting a subset of individuals that resisted prior control approaches. Although the effort did not result in eradication, the evaluation of identified indicators allowed for timely adjustments to removal using the ARM process.The snake removal efforts yielded an avian response in the treatment area after integrating live birds as snake lures, suggesting functional eradication of snakes may be possible. We also, however, observed a release of invasive rodents following snake control, with birds being more sensitive to the presence of snakes than rodents.Synthesis and applications. We suggest that using adaptive resource management to evaluate each phase of action in relation to established goals allowed us to measure outcomes and was successful in eliminating uncertainty in the application of control tools for wildlife conservation. We were able to create a documented and successful approach towards removing snakes inside a snake‐exclusion barrier by following the ARM process. [ABSTRACT FROM AUTHOR]

In October 2020, a new population of invasive brown treesnakes (Boiga irregularis) was discovered on the 33-ha Cocos Island, 2.5 km off the south coast of Guam. Cocos Island is a unique conservation resource, providing refuge for many lizards and birds, including endangered species, which were extirpated from mainland Guam by invasive predators including brown treesnakes. We sought to evaluate the usefulness of toxic baiting with acetaminophen-treated carrion baits and cage trapping, common tools for the control of brown treesnakes on mainland Guam, as potential eradication tools on Cocos Island. We evaluated multiple bait types and bait presentations: on the ground, suspended in the canopy emulating aerial bait applications and in four plastic-tube bait station configurations intended to exclude non-target species. We monitored all baits with time-lapse cameras. Despite improved exclusion of non-targets by bait station design, most baits were quickly removed by non-target species, particularly coconut crabs (Birgus latro) and Mariana monitors (Varanus tsukamotoi). Monitoring of 1,250 baits available for 2,427 bait nights resulted in no observations of brown treesnakes taking any bait. Subsequently, we tested two trap types commonly used on Guam and compared trapping success with live versus dead mouse lures. In 10,553 trap nights using live and dead mouse lures, we only captured one brown treesnake, in a trap with a live mouse lure. These baiting and trapping rates are so low as to be ineffectual for all practical purposes. Concurrent visual searching and hand capture of brown treesnakes during initial rapid response efforts demonstrates that these low baiting and trapping success rates are not a result of low snake density. We make a case for our assumption that the ineffectiveness of these tools on Cocos Island is due to the context of extremely high abundance of preferred live prey, primarily large geckos and birds. Our results have profound conservation ramifications, because any future island invasions by brown treesnakes are likely to occur within similarly prey-rich environments where these baiting and trapping methods might be similarly ineffective. [ABSTRACT FROM AUTHOR]

The nocturnal brown treesnake (Boiga irregularis; BTS) was accidentally introduced to the island of Guam, USA, in the Western Pacific in 1945. The BTS has spread throughout all terrestrial habitats, causing wildlife loss and economic damage. Several tools and techniques have been developed to locally reduce BTS numbers and prevent their spread to other islands. The common analgesic acetaminophen has been registered as a low-risk pesticide to manage BTS in non-residential areas. Prior to a more intensive toxic baiting campaign on Andersen Air Force Base, Guam, as part of a larger study to evaluate the effects of BTS control on native bird survival, we conducted a pilot study from May 18 to October 6, 2020, to assess the efficacy and safety of BTS baiting within a residential area. We administered large and small domesticated mouse (Mus musculus) and bird chick (Coturnix japonica and Gallus domesticus) nontoxic carrion baits (without acetaminophen) in bait stations to evaluate BTS and nontarget bait take rates, bait preferences, movements following nighttime bait uptakes, and interactions of humans and domestic animals with baits. We monitored baits with cameras and implanted them with radio-transmitters to verify the species taking the bait and to track BTS to their daytime sheltering locations. Successful BTS bait take rates were low at 20 of 482 baits (4.1%), as were nontarget bait take rates (4 baits; 0.8%). No preference among bait types was discernible, though power to detect differences was limited due to low overall uptake. All first daytime refugia were within vegetation except for 1 location on the roof of a house. No evidence of bait removal or human tampering was found at any of the bait stations. Based on our pilot study, there appeared to be little human or nontarget risk from acetaminophen baiting in this relatively uniform and sparsely vegetated residential area. Because most of the residential areas on Guam are much more variable, similar assessments within a broader diversity of residential areas may be advisable before promoting large-scale use of acetaminophen for managing BTS in close contact with human habitations. [ABSTRACT FROM AUTHOR]

The design of successful invasive species control programs is often hindered by the absence of basic demographic data on the targeted population. Establishment of invasive Burmese pythons (Python molurus bivittatus) in the Greater Everglades Ecosystem, Florida USA has led to local precipitous declines (> 90%) of mesomammal populations and is also a major threat to native populations of reptiles and birds. Efforts to control this species are ongoing but are hampered by the lack of access to and information on the expected biological patterns of pythons in southern Florida. We present data from more than 4,000 wild Burmese pythons that were removed in southern Florida over 26 years (1995-2021), the most robust dataset representing this invasive population to date. We used these data to characterize Burmese python size distribution, size at maturity, clutch size, and seasonal demographic and reproductive trends. We broadened the previously described size ranges by sex and, based on our newly defined size-stage classes, showed that males are smaller than females at sexual maturity, confirmed a positive correlation between maternal body size and potential clutch size, and developed predictive equations to facilitate demographic predictions. We also refined the annual breeding season (approx.100 days December into March), oviposition timing (May), and hatchling emergence and dispersal period (July through October) using correlations of capture morphometrics with observations of seasonal gonadal recrudescence (resurgence) and regression. Determination of reproductive output and timing can inform population models and help managers arrest population growth by targeting key aspects of python life history. These results define characteristics of the species in Florida and provide an enhanced understanding of the ecology and reproductive biology of Burmese pythons in their invasive Everglades range. [ABSTRACT FROM AUTHOR]

Rats (Rattus spp.) are likely established on 80-90% of the world's islands and represent one of the most damaging and expensive biological invaders. Effective rat control tools exist but require accurate population density estimates or indices to inform treatment timing and effort and to assess treatment efficacy. Capture-mark-recapture data are frequently used to produce robust density estimates, but collecting these data can be expensive, time-consuming, and labor-intensive. We tested a potentially cheaper and easier alternative, chew-cards, as a count-based (quantitative) index of invasive rat densities in tropical forests in the Mariana Islands, an archipelago in the western North Pacific Ocean. We trialed chew-cards in nine forest grids on two Mariana Islands by comparing the proportion of cards chewed to capture-mark-recapture density estimates and manipulated rat densities to test whether the relationship was retained. Chew-card counts were positively correlated with rat capture-mark-recapture density estimates across a range of rat densities found in the region. Additionally, the correlation between the two sampling methods increased with the number of days chew-cards were deployed. Specifically, when chew-cards were deployed for five nights, a 10% increase in the proportion of cards chewed equated to an estimated increase in rat density of approximately 2.4 individuals per ha (R2 = 0.74). Chewcards can provide a valid index of rat densities in Mariana Island forests and are a cheaper alternative to capture-mark-recapture sampling when relative differences in density are of primary interest. New cost-effective monitoring tools can enhance our understanding and management of invaded islands while stretching limited resources further than some conventional approaches, thus improving invasive species management on islands. [ABSTRACT FROM AUTHOR]

From a management perspective, reptiles are relatively novel invasive taxa. Few methods for reptile control have been developed and very little is known about their effectiveness for reducing reptile populations, particularly when the goal is eradication. Many reptiles, and especially snakes, are cryptic, secretive, and undergo extended periods of inactivity, traits that decrease detection probabilities and create challenges in estimating population size or evaluating management effects. The brown treesnake (Boiga irregularis) is a notorious invasive species that continues to cause major ecological and economic harm following their introduction to the island of Guam after World War II. They have been the subject of intensive research on the effectiveness of various techniques to control snakes, including the first ever aerial system for the distribution of toxic acetaminophen baits for reptile control. We provide a cohort‐based life table for a cryptic and invasive reptile undergoing extended population control using toxic baits from March 2017–2020. We also evaluated the effects of single (toxic bait) versus multi‐tool (toxic bait and live trapping) management efforts on population trajectories, and estimated which population vital rates are most important for influencing population growth or decline in a treated landscape. Treatment of the population with acetaminophen‐laced baits resulted in an immediate reduction followed by a gradual population decline that suggested that eradication was the probable outcome given sufficient treatment time but that the period of treatment was decades in magnitude. Inclusion of live trapping reduced the predicted time required to achieve eradication by more than half. Preventing the transition of 1,000‐mm snout‐vent length (SVL) females to larger sizes was predicted to have the greatest effect on population reduction based on integral projection modeling. Our results suggest that toxic baits are capable of eradicating brown treesnakes in an enclosure, although inclusion of trapping reduced overall treatment time required. Tools that effectively target females >1,000 mm SVL may have the greatest effect on reducing overall treatment timelines. [ABSTRACT FROM AUTHOR]

Detection of invasive species and decisions centered around early detection and rapid response (EDRR) are notorious challenges for decision makers. Detection probability is low for cryptic species, resources are limited, and ecological harm (especially for island ecosystems) can result from failure to remove invasive species due to inadequate or delayed surveillance efforts. Due to the proximity to the U.S. territory of Guam and inter-island traffic, the Commonwealth of the Northern Mariana Islands (CNMI) is at high risk of colonization by the invasive and cryptic brown treesnake (Boiga irregularis; BTS). There have been numerous reports of snakes and 7 confirmed specimens secured at ports of entry on the island of Saipan in the CNMI over the last four decades, raising the possibility that a population might be established. Establishment of BTS on Saipan is a major concern, as evidenced by the ecological and economic disruption that occurred on Guam. We evaluated the possibility of a small localized population on Saipan using evidence from surveillance efforts in 1999, 2007, 2009, 2016, and 2018, and from results of expert assessment of the credibility of non-confirmed reports of snakes for the period 1982--2013. For active surveillance efforts, we use a Poisson-based model to estimate the 95% probability of at least one snake being detected at a stated density given the level of sampling effort and detection probability. Based on this collective evidence we conclude there is a low probability that Saipan currently has an incipient population of BTS. However, with the continued presence of BTS on Guam, continuing commercial and military transportation in the region, and relief shipments responding to increased storm intensity, Saipan remains highly vulnerable to accidental introductions. Effective surveillance remains a crucial element for detection of any species, but this may be particularly true for a cryptic snake that is difficult to control once established. [ABSTRACT FROM AUTHOR]

The combination of snake-proof barriers and an aerial toxicant-delivery system for snake suppression may allow large-scale control of invasive brown treesnakes (Boiga irregularis) on Guam. However, suppression or local eradication of several other species (e.g., introduced ungulates, cats, rodents) may be required for successful restoration and recovery of forest habitat and reintroduction of native fauna. Islandwide eradication of invasive species is unlikely on Guam, and existing snake-proof barriers are largely ineffective against cats, rodents, shrews, or monitor lizards. Improved barrier technology and pest-control tools may together provide a viable solution to support localized restoration of species and habitats. We designed and tested prototype multispecies barriers using materials known to repel ungulates, cats, and rodents, with a focus on testing the ability of a rolled hood installed over three different mesh designs to repel brown treesnakes and black rats (Rattus rattus). Woven wire (4.9 × 12 mm aperture, 2.5 mm dia. wire) repelled 99.1% of all snakes, including = 1031 breach attempts by 106 individuals and 2 successful breaches by 1 small individual. Woven wire (6 × 6 mm aperture, 2.7 mm dia. wire) repelled 100% of all snakes, including 611 breach attempts by 65 individuals. Mini chain link mesh (7 × 9 mm aperture, 1 mm dia. wire) repelled 100% of all snakes, including 1053 breach attempts by 97 individuals. Brown treesnakes were unable to climb either of the two woven wire designs (1642 breach attempts by 171 individuals), making the rolled hood serve as a redundant secondary snake barrier. The rolled hood repelled 100% of all snakes when individuals were provided a climbable surface to access the hood (94 breach attempts by 39 snakes). The probability of a snake being able to climb the mini chain link mesh was inversely related to snout-vent length. The rolled hood repelled 100% of all rats, with 5080 breach attempts by 21 individuals. Recommended next steps include consultation with engineers to address wind loading, structural integrity, material interactions, and integration of decision-support tools to optimize cost and efficacy of barrier designs on the landscape. [ABSTRACT FROM AUTHOR]

The brown treesnake (Boiga irregularis) was accidentally introduced to Guam and caused severe ecological and economic damages. Acetaminophen is an effective, low-risk oral toxicant for invasive brown treesnakes, and an automated aerial delivery system (ADS) has been developed for landscape-scale toxic bait distribution. A fixed dose of 80 mg of acetaminophen within a tablet inserted into a dead neonatal mouse (DNM) was lethal for all brown treesnakes in previous trials; however, these trials did not include very large individuals which are difficult to acquire for testing. Because most reptiles continue to grow throughout their lifespan, a small number reach much greater than average body sizes. Here, we tested effectiveness of 80 mg acetaminophen DNM baits for unusually large brown treesnakes as they became available. Our results confirmed that an 80 mg dose is lethal for the vast majority of snakes on Guam, but efficacy starts to diminish around 200 g of body mass. We also tested an alternative mouse bait configuration with 160 mg of acetaminophen that could be incorporated into the ADS to improve control of unusually large snakes. The 160 mg dose is expected to be effective for nearly all female snakes; males grow much larger and additional methods will be needed for extraordinarily large individuals. We describe a full dose-response curve for brown treesnakes to acetaminophen tablets and estimate the LD90 at 299 mg/kg and the LD99 at 578 mg/kg. To our knowledge, this is the first published dose-response curve for an invasive vertebrate with indeterminate growth. [ABSTRACT FROM AUTHOR]

Transect surveys are frequently used to estimate distribution and abundance of species across a landscape, yet a proportion of individuals present will be missed because either they were out of view and unavailable for detection or they were available but not detected because the surveyors missed them. These situations lead to availability and perception bias, respectively, and can result in misleading estimates of abundance and habitat use. In this study, we examined potential biases of visual surveys used for the brown tree snake (Boiga irregularis), a cryptic invasive snake responsible for the extirpation of at least 15 vertebrates on Guam. We simultaneously executed visual surveys and radiotelemetry in a lowdensity population of brown tree snakes with two goals in mind: to assess the efficacy of visual surveys in detecting subjects at low densities and to identify sources of perception and availability bias in such surveys. Results indicated that with considerable effort, visual surveys can predict the presence of this cryptic reptile even at low densities (0.4 animals/ha) but perform poorly at predicting areas of high use resulting in inaccurate estimates of relative habitat importance. Telemetered snakes used densely foliated plants including Pandanus tectorius and ferns (epiphytic and terrestrial species) for nearly half of their time, yet <9% of visual survey observations occurred in these microhabitats. Visibility of snakes decreased as they perched higher in the canopy mirroring the disparity between visual survey and telemetry detections but was also surprisingly low near the forest floor (0–1 m). Microhabitats identified in this study are likely to disproportionately affect visual surveys and would be appropriate resources to target for management purposes. When there is critical need to prevent false negatives, such as during an incipient invasion elsewhere, targeted searches of high-use resources could augment other detection tools to improve detection probabilities of this and other cryptic species. [ABSTRACT FROM AUTHOR]

Invasive predators are responsible for almost 60% of all vertebrate extinctions worldwide with the most vulnerable faunas occurring on islands. The brown treesnake (Boiga irregularis) is a notorious invasive predator that caused the extirpation or extinction of most native forest birds on Guam. The success of avian reintroduction efforts on Guam will depend on whether snake-control techniques sufficiently reduce contact rates between brown treesnakes and reintroduced birds. Mouse-lure traps can successfully reduce brown treesnake populations at local scales. Over a 22-week period both with and without active snake removal, we evaluated snake-trap contact rates for mouse- and bird-lure traps. Bird-lure traps served as a proxy for reintroduced nesting birds. Overall, mouse-lure traps caught more snakes per trap night than did bird-lure traps. However, cameras revealed that bird-lure traps had a snake contact rate almost 15 times greater than the number of successfully captured snakes. Snakes that entered bird-lure traps tended to be larger and in better body condition and were mostly captured in bird-lure traps, despite numerous adjacent mouse-lure traps. Traps placed along grid edges caught more snakes than interior traps, suggesting continuous immigration into the trapping grid within which bird-lure traps were located. Contact between snakes and bird-lure traps was equivalent before and after snake removal, suggesting mouse-lure traps did not adequately reduce the density of snakes that posed a risk to birds, at least at the timescale of this project. This study provides evidence that some snakes exhibit prey selectivity for live birds over live mouse lures. Reliance on a single control tool and lure may be inadequate for support of avian reintroductions and could lead to unintended harvest-driven trait changes of this invasive predator. [ABSTRACT FROM AUTHOR]

Abstract: Overabundant ungulate populations can alter forests. Concurrently, global declines of seed dispersers may threaten native forest structure and function. On an island largely devoid of native vertebrate seed dispersers, we monitored forest succession for 7 years following ungulate exclusion from a 5‐ha area and adjacent plots with ungulates still present. We observed succession from open scrub to forest and understory cover by non‐native plants declined. Two trees, native Hibiscus tiliaceus and non‐native Leucaena leucocephala, accounted for most forest regeneration, with the latter dominant. Neither species is dependent on animal dispersers nor was there strong evidence that plants dependent on dispersers migrated into the 5‐ha study area. Passive restoration following ungulate removal may facilitate restoration, but did not show promise for fully restoring native forest on Guam. Restoration of native forest plants in bird depopulated areas will likely require active outplanting of native seedlings, control of factors resulting in bird loss, and reintroduction of seed dispersers. [ABSTRACT FROM AUTHOR]

The article discusses research on the specie, "Boiga Irregularis (Brown Treesnake)" and explores about its geographical distribution and collection of specimen.

As mitigation- and conservation-driven translocations of declining species escalate, establishing best practices for conservation practitioners is critical. A variety of factors, such as individual behaviour, may influence post-release behaviour and survival. Here, we explored the role of individual personality in predicting post-translocation survival and behaviour in juvenile desert tortoises (Gopherus agassizii). Using an experimental design with captive tortoises, we found that individual tortoises displayed clear personalities along bold-shy and investigative or exploratory continuums. Following release, personality correlated with burrow use and survival in the wild. Individuals with more exploratory personalities were encountered in burrows more often and experienced higher survival. Among the variables analysed, burrow use was also one of the strongest predictors of survival. Thus, we infer that exploratory tortoises were more likely to find and use refugia, which was beneficial to translocated tortoises. Dispersal after release was unrelated to personality, although males dispersed farther than females. Strikingly, females experienced a rate of mortality that was almost twice that of males, with no measured size differences between the sexes. We conclude that desert tortoise do have personalities which can influence survival following translocation, but which have limited implications for post-release dispersal. [ABSTRACT FROM AUTHOR]

The article focuses on developing and comparing external attachment methods for radio transmitters on Brown Treesnakes (Boiga irregularis), aiming to find a less invasive alternative to coelomic transmitter implantation. Topics include the effectiveness and practicality of two minimally invasive methods ("glue-and-tape" and "tape-glue-tape") previously used with other snake species, evaluated for their impact on snake behavior, movement, and feeding patterns during short-term studies.

The article presents observations of the diet and predation by an adult female Anolis carolinensis or Green Anole of a juvenile Hemidactylus frenatus or Common House Gecko that was captured on a Coconut Palm in a landscaped area near a suburban building on the Pacific Island of Guam on June 25, 2021. The diet of an Anolis carolinensis cited include invertebrates and saurophagy. The researchers observed stress-related coloration changes in the Anolis carolinensis while consuming the gecko.

Highlights: [•] Examined effect of traffic volume on desert tortoise occurrence and demography. [•] Low traffic volumes had no effect on occurrence but correlated with larger tortoises. [•] Intermediate traffic volumes reduced occurrence at least 50m from the road. [•] High traffic volume roads reduced size and occurrence and increased mortality. [•] Roads may suppress population growth rates of reptiles depending on traffic volumes. [ABSTRACT FROM AUTHOR]

The article provides information on Hemidactylus tenkatei (Spotted house gecko) in Tamuning, Guam, which was collected primarily from rock and cinder walls adjacent to urban areas.

Broad foraging classifications, such as generalist or specialist forager, are generally beneficial for population management in defining expectations of typical behavior. However, better understanding as to how individual variance in behavior interfaces with management actions, such as control of an invasive predator (such as brown treesnakes; Boiga irregularis) responsible for ecological collapse of a taxonomic group (birds), may affect conservation goals. In the context of predator control, better understanding of foraging ecology and prey specificity helps to ensure that food-based control programs are removing the target individuals. We sought to quantify whether differences in a dietary generalist snake species was measurable during captive trials using mice or birds as the prey choice. We presented snakes with prey choices that could be or are integrated with tools deployed by managers for control to directly relate choice or preference to management action. We collected wild brown treesnakes and classified them as bird eaters or of unknown diet based on food items present in their digestive tract at the time of capture. In experimental tests, we used live birds and live mice in traps, as well as bird and mouse carrion presented on platforms, to measure interest, take rates, and repeatability (preference) by snakes. We found that all individuals spent more time investigating live birds than they did mice, independent of dietary history, which resulted in twice as many snakes being captured in traps with live birds compared to live mice. There was, however, roughly equal interest in mouse and bird carrion. Within individuals, there was evidence for decreased interest in mouse carrion, if individuals ate birds in the wild. Choice of carrion type was repeatable across trials, suggesting preference may exist. Overall, interest in both live mice and mouse carrion was greatest for medium-bodied snakes, while interest in bird carrion was independent of snake size. Our results indicate that management of invasive predators, including reptiles, may more rapidly achieve conservation targets when managers consider individual heterogeneity in behavior. For brown treesnakes more interested in birds, managers may remove more snakes if they use avian food lures; increased removal of avian specialists may facilitate avian recovery. [Display omitted] • Individual-level specialization in foraging strategy is of broad management interest. • We tested a generalist, invasive snake species for individual specialization. • We found that larger individuals had lower interest in both live and dead mice. • We also found that snakes that previously fed on birds had preference for dead birds in feeding trials. • Individual diet specialization by an invasive generalist may require targeted removal of problem snakes. [ABSTRACT FROM AUTHOR]

The article provides information on the geographic distribution of Hemidactylus cf. platyurus (Asian flat-tailed house gecko) in Tamuning, Guam.

Reptiles utilize a variety of environmental cues to inform and drive animal behavior such as chemical scent trails produced by food or conspecifics. Decrypting the scent-trailing behavior of vertebrates, particularly invasive species, enables the discovery of cues that induce exploratory behavior and can aid in the development of valuable basic and applied biological tools. However, pinpointing behaviors dominantly driven by chemical cues versus other competing environmental cues can be challenging. Y-mazes are common tools used in animal behavior research that allow quantification of vertebrate chemosensory behavior across a range of taxa. By reducing external stimuli, Y-mazes remove confounding factors and present focal animals with a binary choice. In our Y-maze studies, a scenting animal is restricted to one arm of the maze to leave a scent trail and is removed once scent-laying parameters have been met. Then, depending on the trial type, either the focal animal is allowed into the maze, or a competing scent trail is created. The result is a record of the focal animal's choice and behavior while discriminating between the chemical cues presented. Here, two Y-maze apparatuses tailored to different invasive reptile species: Argentine black and white tegu lizards (Salvator merianae) and Burmese pythons (Python bivittatus) are described, outlining the operation and cleaning of these Y-mazes. Further, the variety of data produced, experimental drawbacks and solutions, and suggested data analysis frameworks have been summarized.