Crotalus Horridus Research Articles

Characterization of patients with a snakebite presenting to healthcare facilities and reported to poison and drug information centers—Arizona, 2017–2021

Introduction Envenomation after a North American rattlesnake (Crotalus spp. and Sistrusus spp.) bite is associated with substantial morbidity. Arizona reports the highest number of rattlesnake envenomations annually in the United States. We evaluated the performance of poison and drug information centers for snakebite surveillance, compared with the hospital and emergency department discharge database. We used both datasets to improve the characterization of epidemiology, healthcare costs, and clinical effects of snakebite envenomations in Arizona. Methods We identified patients with a snakebite during 2017–2021 using Arizona hospital and emergency department discharge data and snakebite consults with two regional Arizona poison centers. Patients were matched using name and birthdate. The performance of poison center data for snakebite surveillance was evaluated using the percentage of snakebite patients in hospital and emergency department discharge data that consulted with poison centers. Patient demographics, healthcare characteristics, clinical effects, and context of snakebite events were described using both datasets. Results In total, 1,288 patients with a snakebite were identified using the Arizona hospital and emergency department discharge data, which resulted in 953 (74%) consultations with poison centers. The median age of patients was 48 years (IQR 28-62 years), and they were predominantly male (66%), White (90%), and non-Hispanic (84%). The median billed charges were US$ 84,880 (IQR US$ 13,286–US$ 168,043); the median duration of a healthcare stay was 34 h (IQR 13–48 h), and 29% of patients were transferred between healthcare facilities. Among 953 consulted poison center calls for a snakebite, a median of 14 vials of antivenom was administered per patient; 375 (60%) bites occurred near the home, and 345 (43%) patients were bitten on a lower extremity. One death was identified. Discussion Snakebites in Arizona can cause severe morbidity and require extensive healthcare resources for treatment. Poison centers are valuable for monitoring venomous snakebites in Arizona. Conclusions Using hospital and emergency department discharge data with poison center records can improve public health surveillance data regarding snakebite epidemiology and human-snake interaction information and be used to tailor interventions to increase awareness of snake encounters and prevent snakebites.

SCHIZANGIELLA INFECTIONS IN AN EASTERN RATSNAKE (PANTHEROPHIS ALLEGHANIENSIS) AND A TIMBER RATTLESNAKE (CROTALUS HORRIDUS).

This report describes Schizangiella infections in colubrid and viperid snakes. A captive eastern ratsnake (Pantherophis alleghaniensis) was presented for a large intraoral mass associated with the mandible. The mass was debulked and histologic examination revealed severe, granulomatous stomatitis with intralesional fungi exhibiting morphologic features consistent with Schizangiella serpentis. PCR and sequencing of affected tissues confirmed S. serpentis. Because of declining health, the ratsnake was euthanized and postmortem examination identified a disseminated S. serpentis infection involving the skeletal musculature, lung, kidney, mesentery, and mandible. A wild-caught timber rattlesnake (Crotalus horridus) was presented for cutaneous lesions, weakness, and lethargy and later died. Postmortem examination revealed a mass-like structure in the esophagus characterized by high numbers of Schizangiella-like fungi associated with extensive granulomatous inflammation; the snake also had cutaneous mycosis suggestive of ophidiomycosis. This is the first report to document the unique morphologic features of S. serpentis in tissues and the presentation of schizangiellosis in snakes. Schizangiellosis should be considered as a differential diagnosis for nodular lesions involving the oral cavity and/or the gastrointestinal tract of snakes.

The Metabolic Effort and Duration of Ecdysis in Timber Rattlesnakes: Implications for Time-Energy Budgets of Reptiles.

AbstractTemperate reptiles are often considered to be low-energy systems, with their discrete use of time and energy making them model systems for the study of time-energy budgets. However, the semifrequent replacement and sloughing of the epidermis is a ubiquitous feature of squamate reptiles that is often overlooked when accounting for time and energy budgets in these animals. We used open-flow respirometry to measure both the energetic effort of ecdysis and the duration of the associated metabolic upregulation (likely related to behavioral changes often reported for animals in shed) in wild-caught timber rattlesnakes (Crotalus horridus). We hypothesized that total effort of skin biosynthesis and physical removal would be related to body mass and expected the duration of the process to remain static across individuals at a fixed temperature (25°C). We provide both the first measurements of the cost of skin biosynthesis and physical removal in a reptile and the highest-resolution estimate of process duration recorded to date. We found that skin biosynthesis, but not the cost of physical removal of the epidermis, was related to body mass. Shed cycle duration was consistent across individuals, taking nearly 4 wk from process initiation to physical removal of the outermost epidermal layer. Total energetic effort of ecdysis was of sizeable magnitude, requiring ∼3% of the total annual energy budget of a timber rattlesnake. Energetic effort for a 500-g snake was equivalent to the amount of metabolizable energy acquired from the consumption of approximately two adult mice. Ecdysis is a significant part of the time-energy budgets of snakes, necessitating further attention in studies of reptilian energetics.

Distribution and drivers of critical hibernacula for the timber rattlesnake Crotalus horridus in Illinois, USA

The dependency on hibernacula for extended periods presents terrestrial reptiles with the challenge of locating thermally adequate hibernacula each winter. Defining the habitat characteristics of hibernacula is crucial for understanding the overwintering requirements and distributions of hibernacula-dependent reptiles, alongside identifying habitats which warrant special conservation concern. Our objectives were to identify the overwintering habitat characteristics of the imperiled timber rattlesnake Crotalus horridus in Illinois, USA, and to determine the distribution of likely hibernacula habitats throughout the state. Due to the initial sparsity of hibernacula records in Illinois, we adopted an iterative habitat suitability modeling process consisting of 3 distinct rounds of Maxent construction and revision. Each round was informed with updated information from model-guided surveys or by building rapport with in-state naturalists and researchers who knew of additional hibernacula locations. We created our final model using 36 hibernacula and identified slope angle (indicative of rock outcrops and shallow soils), topographical position index, forest patch area, and aspect (decomposed into 2 linearized variables: southness and eastness) as important drivers of C. horridus hibernacula habitat in Illinois. Together, the 5 variables and site surveys suggest the suitable overwintering habitat for C. horridus in Illinois is located on south- to southwest-facing outcrops on upper slopes and ridges of larger forest patches. Such habitat is distributed primarily in southern Illinois and throughout the Mississippi River and Illinois River border counties. Our study adds to the current understanding of the species’ overwintering requirements and provides a foundation for future ecological studies, management, and survey efforts throughout Illinois.

Comparative analysis of Deinagkistrodon acutus venom from Taiwan and China utilizing chromatographic, electrophoretic, and bioinformatic approaches, along with ELISA employing a monospecific antivenom

Deinagkistrodon acutus is a medically important pitviper inhabiting mainly South China and Taiwan. The hemorrhagic effects of its envenoming are compatible to its venom, which is abundant in metalloproteases (svMPs) and C-type lectin-like proteins. In this study, we investigated geographic variations in the venom of D. acutus collected from Taiwan and four Mainland Chinese provinces: Fujian, Jiangxi, Anhui, and Hunan. The variations were assessed through high-performance liquid chromatography, non-metric multidimensional scaling analysis, gel electrophoresis, and enzyme-linked immunosorbent assay (ELISA) with a monospecific antivenom (DaMAV) generated against the Taiwanese D. acutus venom, and discussed based on venom-protein sequences in databases and literature related to D. acutus venom. Additionally, the cross-reactivity of DaMAV against Crotalus horridus and Calloselasma rhodostoma venoms was investigated. We noted differential abundances of D. acutus venom metalloproteases, C-type lectin-like proteins, and phospholipase A2, along with point mutations and selective expression of serine protease isoforms. The ELISA results revealed that the venom from Taiwan was more reactive toward Taiwanese DaMAV than the four Mainland Chinese venoms, consistent with chromatographic profile differences, whereas C. horridus venom presented moderate cross-reactivity with DaMAV. The observed immunoreactivities of these venom with DaMAV can be attributed to the high prevalence of their PIII-svMPs, which are the dominant antigens, and the conservation of PIII-svMP epitopes.

Ophidiomycosis in a Timber Rattlesnake, Crotalus horridus (Linnaeus 1758), with behavioral and thermal observations: A case report from Georgia, USA

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Human dimensions of timber rattlesnake (Crotalus horridus) management to reduce human-wildlife conflict

ABSTRACT Human-wildlife interactions are common across fragmented exurban landscapes. To date, most human dimensions research on human-wildlife conflict has focused on large mammalian carnivores, with less attention to smaller, less-charismatic species. Two isolated populations of state-endangered timber rattlesnakes (Crotalus horridus) remain in Connecticut, USA. Our objective was to assess current management, outreach, and collaboration activities associated with an exurban timber rattlesnake population. We conducted qualitative, semi-structured interviews with 16 stakeholders involved with timber rattlesnake management. Results suggested that although forest management does not focus on timber rattlesnakes specifically, participants generally were satisfied with current ecological monitoring practices. Land acquisition and the efforts of volunteers were emphasized as crucial aspects of management and public outreach success. Collaboration associated with timber rattlesnake management has achieved positive outcomes but lacks landscape-level coordination. Paired with ecological efforts, landscape-level leadership offers opportunity for shared resources and recruitment of volunteers to relieve associated capacity constraints.

Home range, site fidelity, and movements of timber rattlesnakes (Crotalus horridus) in west-central Illinois

Understanding the home range of imperiled reptiles is important to the design of conservation and recovery efforts. Despite numerous home range studies for the Threatened timber rattlesnake (Crotalus horridus), many have limited sample sizes or outdated analytical methods and only a single study has been undertaken in the central midwestern United States. We report on the home range size, site fidelity, and movements of C. horridus in west-central Illinois. Using VHF telemetry, we located 29 C. horridus (13 female, 16 male) over a 5-year period for a total of 51 annual records of the species' locations and movements. We calculated annual home ranges for each snake per year using 99%, 95%, and 50% isopleths derived from Brownian Bridge utilization distributions (BBMM), and we also report 100% minimum convex polygons to be consistent with older studies. We examined the effects of sex, mass, SVL, and year on home range sizes and reported on movement metrics as well as home range fidelity using both Utilization Distribution Overlap Index (UDOI) and Bhattacharyya's affinity (BA) statistics. The home range sizes for male and non-gravid C. horridus were 88.72 Ha (CI 63.41–110.03) and 28.06 Ha (CI 17.17–38.96) for 99% BBMM; 55.65 Ha (CI 39.36–71.93) and 17.98 (CI 10.69–25.28) for 95% BBMM; 7.36 Ha (CI 5.08–9.64) and 2.06 Ha (CI 1.26–2.87) for 50% BBMM; and 78.54Ha (CI 47.78–109.30) and 27.96 Ha (CI 7.41–48.51) for MCP. The estimated daily distance traveled was significantly greater for males (mean = 57.25 m/day, CI 49.06–65.43) than females (mean = 27.55 m/day, CI 18.99–36.12), particularly during the summer mating season. Similarly, maximum displacement distances (i.e., maximum straight-line distance) from hibernacula were significantly greater for males (mean = 2.03 km, CI 1.57–2.48) than females (mean = 1.29 km, CI 0.85–1.73], and on average, males were located further from their hibernacula throughout the entirety of their active season. We calculated fidelity to high-use areas using 11 snakes that were tracked over multiple years. The mean BBMM overlap using Bhattacharyya's affinity (BA) for all snakes at the 99%, 95%, and 50% isopleths was 0.48 (CI 0.40–0.57), 0.40 (0.32–0.49), and 0.07 (0.05–0.10), respectively. The mean BBMM overlap for all snakes using the Utilization Distribution Overlap Index (UDOI) at the 99%, 95%, and 50% isopleths was 0.64 (CI 0.49–0.77), 0.32 (CI 0.21–0.47), and 0.02 (CI 0.01–0.05)), respectively. Our results are largely consistent with those of other studies in terms of the influence of sex on home range size and movements. The species also exhibits strong site fidelity with snakes generally using the same areas each summer, though there is far less overlap in specific (e.g., 50% UDOI) high-use areas, suggesting some plasticity in hunting areas. Particularly interesting was the tendency for snakes to disperse from specific hibernacula in the same general direction to the same general areas. We propose some possible reasons for this dispersal pattern.

Frequency and Timing of Ecdysis in Free-Ranging Timber Rattlesnakes

Frequency and Timing of Ecdysis in Free-Ranging Timber Rattlesnakes

Toxinological profile and histopathological alterations induced by Bothrocophias campbelli venom from Colombia

Snakebite envenomings most frequently reported in Colombia are caused by snakes of the genera Bothrops, Bothriechis, Bothrocophias, and Porthidium. Their venoms induce local and systemic pathophysiological effects, sometimes leading to permanent sequelae such as reduced mobility of the limbs, amputations, besides the risk of death. The genus Bothrocophias includes nine species, among which B. campbelli has a distribution restricted to the department of Nariño in Colombia. In this work we determined the toxinological profile its venom, by performing assays for the lethal, hemorrhagic, edematogenic, and myotoxic activities in mouse models, as well as for in vitro coagulant activity on human plasma. The lethal toxicity of the venom was 142.7 µg venom/mouse (111.4–179.8 µg/mouse; 6.6–10.6 µg/g body weight) by intraperitoneal route. Its hemorrhagic activity (minimum hemorrhagic dose: 12.7 ± 2.3 µg) is generally weaker compared to other South American vipers, but edematogenic (minimum edematogenic dose 1.0 ± 0.3 µg), and myotoxic (minimum myotoxic dose 3.9 ± 2.5 µg) activities are very potent. Histopathological examination of the injected mouse gastrocnemius muscle showed prominent disorganization of the myofibrils, myonecrosis, and an intense inflammatory leukocyte infiltrate. In vitro, the minimal coagulant dose was 12.3 ± 0.5 µg. Overall, this toxinological profile would predict that the clinical picture of envenomings by B. campbelli might be characterized by moderate disturbances in the coagulation cascade, mild local hemorrhage, and, conversely, severe myonecrosis and edema, which could potentially lead to compartment syndrome and gangrene.

Spatial Analysis of Attitudes Toward Timber Rattlesnakes (Crotalus Horridus) Where Encounters Occur Within an Exurban Landscape

Most human-wildlife conflict research has focused on large species, with less attention to smaller, less-charismatic species. Our objective was to evaluate landscape-level spatial relationships among human-timber rattlesnake (Crotalus horridus) encounters, attitudes toward timber rattlesnakes, and exurban residential context. Encounters and attitudes data were collected using a mail survey and encounter reports (n = 583). Residential context variables focused on land cover and parcel characteristics. Encounters and similar attitudes toward timber rattlesnakes were spatially clustered on the landscape, and residential context attributes influenced both. Some overlap existed between favorable attitudes related to coexistence with timber rattlesnakes and relatively low concern about the species, whereas encounter-similar attitude clusters were distinct with less overlap. An outreach approach with prescribed messaging strategies based on the localized frequency of encounters, relative attitudes, and land cover may facilitate ability to address resident concerns in an individualized way.

The rocks are hotter on the other side of the fence: roadside habitats should inform mitigation design

Maintaining viable populations of large reptiles is often challenging in road fragmented landscapes. While mitigation structures can reduce impacts, few studies have investigated how mitigation success can be affected by roadside habitats. In southeast Ohio, USA, we evaluated mitigation effectiveness for state-endangered timber rattlesnakes (Crotalus horridus) at a new highway in a forested landscape. Road construction at the study site created a wide corridor of open canopy habitats (the right-of-way; ROW) containing roadcuts and stone piles. However, exclusion fencing was constructed along the forest-ROW boundary, leaving the open canopy habitats on the road-side of the fence. Over three years, we monitored 6 rattlesnakes using radiotelemetry and found that rattlesnakes repeatedly crossed the fence to access forest-edge and ROW habitats. Rattlesnakes ostensibly crossed through damaged sections of the fence. The ROW was used most intensively by gravid females (n = 2), with their core home ranges overlapping the ROW by more than 50 percent. Despite the fence crossings, all home ranges were bounded by the highway and no rattlesnake road mortality was observed. Operative temperature models revealed that the ROW provided warmer thermal regimes that were rare or unavailable in the forest. On average, field preferred gestation temperatures (Tb = 29.7°C, SD = 1.8) could be attained or exceeded for more than 5 times as many hours per day in the ROW (7.8 hours) than in the forest (1.4 hours). Habitat selection models indicated gravid females selected warmer thermal habitats that were spatially concentrated in the ROW and edge habitats, while non-gravid snakes avoided the ROW beyond the forest edge. Habitat use within the ROW was mostly limited to rocky microhabitat structures, especially riprap stone piles and subsurface rock crevices on roadcuts, which provided buffered thermal regimes with refugia from extreme temperatures during the day and warmer Te through the night. In forested landscapes, we encourage road planners to consider whether new road corridors are likely to introduce basking sites, and if so, maintain those features on the habitat-side of exclusion fencing, and consider restoring basking sites in the surrounding forest to reduce the potential for ecological trap formation.

Timber rattlesnake (Crotalus horridus): Biology, conservation, and envenomation in the Upper Mississippi River Valley (1982-2020).

The Timber Rattlesnake (Crotalus horridus) is the largest pit viper in the Northern United States and is the prominent venomous snake species indigenous to the bluff land habitats of the Upper Mississippi River Valley (UMRV). Conservation of C. horridus in this geographic region not only preserves the ecosystem's biodiversity and ecological balance, but also assures the continued study of their biomedically important venoms/toxins. Field studies of C. horridus biology and natural history performed from 1985 to 2015 in southeastern Minnesota and western Wisconsin along the Mississippi River showed populations have declined. Consequently, the implementation of improved conservation measures afforded the species protective status in both states. Historically, accounts of Timber Rattlesnake bites in the UMRV have been sparse, and medical consequences of envenomation have had limited documentation. However, in recent decades cases of envenomation by C. horridus have continued to occur. Retrospective analysis of clinical toxinology consultations documented from 1982 to 2020 on cases of envenomation by C. horridus in the UMRV revealed a very low incidence of bites annually and revealed that their venom can induce a rapid and precipitous decline in platelets.

Neurologic and hematologic sequalae following a timber rattlesnake (Crotalus horridus) envenomation in a dachshund.

A 2-year-old female Dachshund had a witnessed timber rattlesnake envenomation. Although rattlesnake envenomations are a common, potentially life-threatening event in companion animals, timber rattlesnake envenomations in the dog are rarely reported. This dog described in this case report had significant hematologic and neurologic clinical derangements consistent with Types A and B rattlesnake venom and a suspected hypersensitivity reaction to the venom. This patient was treated aggressively with antivenom and fully recovered without any persistent neurologic signs at follow-up.

Observation of an Interaction between an Allegheny Woodrat (Neotoma magister) and a Timber Rattlesnake (Crotalus horridus) in Pennsylvania

Neotoma magister (Allegheny Woodrat) is a threatened species in Pennsylvania and listed as Endangered in 4 of 5 bordering states. Declining food resources, genetic isolation, habitat fragmentation, disease, and increasing predator populations are considered the primary threats to Allegheny Woodrat populations. Herein, we share an observation captured on a wildlife camera of an adult woodrat displaying agonistic behavior toward a small Crotalus horridus (Timber Rattlesnake).

Scale-dependent effects of roadways on the movement behavior of a large-bodied pit viper (Crotalus horridus)

Roadways are among the most widespread and disruptive anthropogenic land use features that influence the behavior and movement of wildlife. Negative impacts of roadways have been well documented, but the behavioral impact of roadways on smaller, cryptic species has yet to be thoroughly examined. Using a novel integration of radio telemetry and tri-axial accelerometry, we evaluated the effects of roadways on the movement behavior of 26 adult Timber Rattlesnakes (Crotalus horridus) at coarse and fine time scales in central Georgia between June 2020 and November 2021. To interpret the effect of roads at a coarse time scale, we modeled the effect of mean annual distance to roadways (DTR) on annual measures of movement and space use by C. horridus using both radio telemetry and accelerometry derived metrics (RT and ACT metrics). To explore the fine-scale impact of roadways, we quantified RT and ACT metrics during confirmed road interactions (i.e., instances when individual snakes crossed a road or encountered a road but did not cross) and compared these instances to the RT and ACT metrics calculated across the remainder of the active season within this subset of snakes. Relating the annual RT and ACT metrics to DTR revealed no significant associations at a coarse time scale. However, the evaluation of C. horridus movement behavior during punctuated road encounters revealed that snakes increased RT and ACT metrics during the road interactions compared to metrics calculated across the remainder of the active season. This might indicate that the abundance of contiguous habitat adjacent to roadways at our study site is serving as an adequate buffer to any long-term shifts in movement behavior, but the potential hidden cost of increasing movement when snakes encounter roads could have negative implications for populations that encounter roads more frequently, even in the absence of significant direct road mortality. Overall, integrating radio telemetry and accelerometry and adopting a scale-dependent approach to quantifying movement allowed for a more detailed evaluation of the response of C. horridus to roadways. This approach holds promise for detecting and interpreting previously overlooked short-term alterations in snake movement behavior with potentially significant fitness consequences.

The use of serum protein analysis in the diagnosis of fatal envenomation via Crotalus horridus (timber rattlesnake)

Deaths occurring due to rattlesnake envenomization are extremely rare and must be thoroughly investigated in the same manner as any other type of death. Our research presents the case of an adult white male who suffered a fatal timber rattlesnake (Crotalus horridus) envenomation in northwest Florida in 2018. Blood samples were taken from the decedent's heart and vasculature of the chest and sent for serum proteomic analysis. Serum proteomic analysis was utilized in order to identify proteins from timber rattlesnake (C.horridus) found within the victim's blood. The confirmation of the presence of timber rattlesnake venom within the victim's blood allows the forensic pathologist to determine the cause of death most accurately and likewise, assists with the manner of death determination. Blood samples were separated into two groups: one with the abundant endogenous proteins depleted to facilitate detection of lower abundant proteins and one undepleted. In the depleted sample, a total of 712 proteins were identified, with 47 of the proteins (6.6%) occurring originating from timber rattlesnake (C.horridus). Likewise, a total of 742 proteins were identified in the undepleted sample, with 52 of the proteins (7.0%) occurring in timber rattlesnake (C.horridus). No timber rattlesnake (C.horridus) proteins were found in control human serum.

Severe, persistent thrombocytopenia in Crotalus horridus envenomation despite antivenom: A retrospective review

BackgroundIn the late nineties, Bond and Burkhardt described a severe thrombocytopenic phenomenon from envenomation by Crotalus horridus. This thrombocytopenia persisted despite administration of platelets and antivenom. Questions remain regarding the clinical significance and time to resolution of this thrombocytopenia. In addition, as new antivenoms are available in North America, the response to current treatment is not well reported. The purpose of this study is to provide further insight into the approach to treatment of Crotalus horridus envenomation. MethodsThis is a retrospective chart review of 21 cases of presumed envenomation by C. horridus. Data collected included age, sex, antivenom administration, laboratory data, length of hospital stay, blood products administered, and general clinical course. We also evaluated platelet response to antivenom, bleeding outcomes, and complications from envenomation. ResultsPatients' ages ranged from 19 to 71 years. All patients were men. Most patients presented with thrombocytopenia and all had limb swelling. Patients responded initially to antivenom treatment, however subsequently developed a profound thrombocytopenia, including fourteen with platelet counts less than 20 × 109/L. Abnormalities in thromboelastography (TEG) were noted in conjunction with thrombocytopenia. Patients displayed persistent thrombocytopenia despite administration of Crotalidae polyvalent immune Fab or Crotalidae immune F(ab’)2. Median time to rebound platelet count greater than 20 × 109/L was ten days (range 6–12 days) from envenomation. Complications included a partial finger amputation in one patient, bleeding gums in four patients, bloody stools in two patients, bloody nasogastric output in one patient. No patients required red blood cell transfusion and no deaths occurred. ConclusionPractitioners treating C. horridus should recognize the possibility of severe thrombocytopenia and its persistence despite antivenom. They should counsel patients on appropriate abstention from activities that could lead to trauma, as well as the importance of follow up for repeat laboratory studies to ensure the resolution of thrombocytopenia.

Phenology and predictors of spring emergence for the Timber Rattlesnake (Crotalus horridus).

Many temperate reptiles survive winter by using subterranean refugia until external conditions become suitable for activity. Determining when to emerge from refugia relies on the ability to interpret when above-ground environmental conditions are survivable. If temperate reptiles rely on specific environmental cues such as temperature to initiate emergence, we should expect emergence phenologies to be predictable using local climatic data. However, specific predictors of emergence for many temperate reptiles, including the Timber Rattlesnake (Crotalus horridus), remain unclear, limiting our understanding of their overwintering phenology and restricting effective conservation and management. Our objectives were to identify environmental cues of spring emergence for C. horridus in Illinois to determine the species' emergence phenology, and to examine the applicability of identified cues in predicting emergence phenology across the species' range. We used wildlife cameras and weather station-derived environmental data to observe and predict the daily surface presence of C. horridus throughout the late winter and early spring at communal refugia in west-central and northern Illinois. The most parsimonious model for predicting surface presence included the additive effects of maximum daily temperature, accumulated degree days, and latitude. With a notable exception in the southeastern U.S., the model accurately predicted the average emergence day for eight other populations range wide, emphasizing the importance of temperature in influencing the phenological plasticity observed across the species' range. The apparent broad applicability of the model to other populations suggests it can be a valuable tool in predicting spring emergence phenology. Our results provide a foundation for further ecological enquiries and improved management and conservation strategies.

Head-Starting and Conservation of Endangered Timber Rattlesnakes (Crotalus horridus horridus) at Roger Williams Park Zoo

The timber rattlesnake (Crotalus horridus horridus) is extinct in Rhode Island and Maine with populations in the remaining New England states afforded endangered species status. Lou Perrotti, Director of Conservation and Research at Roger Williams Park Zoo (RWPZ), has long been a champion of these unloved animals in peril and spearheaded a program at the zoo in fall 2010 to work on the recovery of this endangered snake species. Partnering with multiple state agencies was required to begin saving this maligned native species, which had seen massive population reductions. The program began with accepting adults of varying size and sex suffering from skin lesions believed to be Snake Fungal Disease from multiple New England states. Depending on the severity of the infection, the animals were treated and then released. As the program evolved, it became a goal to not only treat affected adults and determine the overall health of declining New England populations but to begin a head-start program with one of the state conservation partners. Head-starting refers to when neonates are either born in a zoological facility or captured in the wild and raised under managed care until a desired size is reached. They are then released back to the wild, giving them a better chance for survival. The area where the snakes are kept at the zoo allows for temperature manipulation to simulate a natural temperature change and allow for the brumation of individuals. Once the appropriate size is reached, a radio transmitter is surgically implanted to allow radio telemetry tracking after release. The head-starting strategy has been a success, with individuals being found years later, suggesting they are surviving in the wild. Due to the sensitive nature of this program, some data and names of partners have been purposely omitted.