Coyotes (Canis latrans) are novel predators throughout the southeastern United States and their depredation of white-tailed deer (Odocoileus virginianus) neonates may explain observed declines in ...some deer populations in the region, but direct evidence for such a relationship is lacking. Our objective was to quantify neonate survival rates and causes of mortality at the United States Department of Energy's Savannah River Site (SRS), South Carolina to directly evaluate degree of predation in this deer population. From 2006 to 2009, we radio-monitored 91 neonates captured with the aid of vaginal implant transmitters in pregnant adult females and opportunistic searches. Overall Kaplan—Meier survival rate to 16 weeks of age was 0.230 (95% CI = 0.155—0.328), and it varied little among years. Our best-fitting model estimated survival at 0.220 (95% CI = 0.144—0.320). This model included a quadratic time trend variable (lowest survival rate during the first week of life and increasing to near 1.000 around week 10), and Julian date of birth (survival probability declining as date of birth increased). Predation by coyotes was the most frequent cause of death among the 70 monitored neonates that died, definitively accounting for 37% of all mortalities and potentially accounting for as much as 80% when also including probable coyote predation. Predation by bobcats (Felis rufus) accounted for 7% (definitive) to 9% (including probable bobcat predation) of mortalities. The level of coyote-induced mortality we observed is consistent with the low recruitment rates exhibited in the SRS deer population since establishment of coyotes at the site. If representative of recruitment rates across South Carolina, current harvest levels appear unsustainable. This understanding is consistent with the recent declining trend in the statewide deer population. The effects of coyote predation on recruitment should be considered when setting harvest goals, regardless of whether local deer population size is currently above or below desired levels, because coyotes can substantially reduce fawn recruitment. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Predation by coyotes {Canis latrans) on white-tailed deer (Odocoileus virginianus) neonates has led to reduced recruitment in many deer populations in southeastern North America. This low recruitment ...combined with liberal antlerless deer harvest has resulted in declines in some deer populations, and consequently, increased interest in coyote population control. We investigated whether neonate survival increased after coyote removal, whether coyote predation on neonates was additive to other mortality sources, and whether understory vegetation density affected neonate survival. We monitored neonate survival for 4 years prior to (2006-2009) and 3 years during (2010-2012) intensive coyote removal on 3 32-km² units on the United States Department of Energy's Savannah River Site, South Carolina. We removed 474 coyotes (1.63 coyotes/km² per unit per year), reducing coyote abundance by 78% from pre-removal levels. The best model (w¡=0.927) describing survival probability among 216 radio-collared neonates included a within-year quadratic time trend variable, date of birth, removal treatment, and a varying removal year effect. Under this model, survival differed between pre-treatment and removal periods and it differed among years during the removal period, being >100% greater than pre-treatment survival (0.228) during the first removal year (0.513), similar to pre-treatment survival during the second removal year (0.202), and intermediate during the third removal year (0.431). Despite an initial increase, the overall effect of coyote removal on neonate survival was modest. Mortality rate attributable to coyote predation was lowest during the first removal year (0.357) when survival was greatest, but the mortality rate from all other causes did not differ between the pretreatment period and any year during removals, indicating that coyote predation acted as an additive source of mortality. Survival probability was not related to vegetation cover, either directly or in interaction with coyote abundance. When the objective is to increase the recruitment of white-tailed deer, we conclude that neither coyote control nor vegetation management appear effective. Reduction of the antlerless harvest may be necessary to meet this objective, but this harvest strategy warrants additional research in Southeastern deer populations. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
Recent evidence from across the southeastern United States indicating high predation rates by coyotes (Canis latrans) on white-tailed deer (Odocoileus virginianus) fawns has led some managers to ...implement coyote control. Although some evidence suggests coyote control can improve recruitment, success appears to be site dependent. Therefore, we designed an experiment to assess feasibility of coyote control as a management action to increase recruitment on B.F. Grant and Cedar Creek Wildlife Management Areas (WMA) in central Georgia, USA. We estimated annual coyote abundance during 2010–2012 using a noninvasive mark–recapture design and fawn recruitment using infrared-triggered camera surveys. During March–June 2011 and March–April 2012, trappers removed coyotes from both sites. Estimates of coyote abundance on B.F. Grant WMA after trapping were 81% (2011) and 24% (2012) lower than during preremoval. Coyote abundance estimates were similar among years on Cedar Creek WMA. Fawn recruitment on B.F. Grant WMA averaged 0.65 fawns/adult female prior to removal and 1.01 fawns/adult female during the 2 years following the removals. Fawn recruitment on Cedar Creek WMA did not differ among years during the study, and was similar to that prior to coyote arrival. The differential coyote impacts and variable effectiveness of trapping we observed on nearby sites suggest coyote control may not achieve management objectives in some areas. Furthermore, transient behavior and the potential for coyotes to adapt to control efforts likely reduce efficacy of this management action. However, we observed an increase in recruitment on B.F. Grant WMA during one year, and others have seen similar responses. Therefore if lowered fawn recruitment is hindering achievement of management objectives, we recommend managers who opt to control coyotes continuously monitor recruitment to determine whether a response occurs.
Integrating Global Positioning System (GPS) technology with expandable collars will allow researchers to more accurately and efficiently investigate survival of white‐tailed deer (Odocoileus ...virginianus) fawns. We tested fit and function of 5 expandable GPS collar prototypes on white‐tailed deer fawns and conducted behavioral observations during the first 12 weeks of life at the Whitehall Deer Research Facility, Athens, Georgia, USA, during 2018–2020. We fitted 46 fawns with 5 prototype collar designs and ear‐tagged 15 control fawns without collars. Prototype collars differed in expandable band materials. Premature expansion and breakage of collar bands composed of cotton and rubber was a problem that resulted in freely moving collars and displacement to the waist of fawns. Fawns retained prototype collar designs with cotton and rubber band materials for a mean 101 (±46 SD) and 70 (±37) days, respectively. For 2 collar designs with expandable bands composed of nylon and rubber, fawns retained collars for a mean 246 (±156) and 306 (±99) days, respectively. Vectronic (v1.0 and v2.0; VECTRONIC Aerospace GmbH, Berlin, Germany) and Telonics v2.0 (Telonics Inc., Mesa, AZ, USA) collared fawns were 16–21% less likely to be observed standing compared to uncollared fawns. Bedded Vectronic (v1.0 and v2.0) and Telonics v2.0 collared fawns were 19–28% less likely to be observed with their head up compared to uncollared fawns. Bedded fawns with collars were 11–16% more likely to be observed with their head tilted compared to bedded fawns without collars. Vectronic (v1.0 and v2.0) and Telonics v2.0 collared fawns were 25–34% less likely to exhibit vigilance compared to uncollared fawns, and all collared fawns were 22–37% more likely to exhibit sleeping than uncollared fawns. We recommend that GPS collar designs we evaluated undergo additional modifications before deployment in the field, including improved stitching patterns and threads to facilitate more gradual collar expansion, smaller battery housings and improved weight distribution to mitigate behavioral concerns, and smaller band circumferences to improve collar fit across time.
We recommend that GPS collar designs for neonatal white‐tailed deer undergo additional modifications before deployment in the field, including improved stitching patterns and threads to facilitate a more gradual collar expansion, smaller battery housings and improved weight distribution to mitigate behavioral concerns, and smaller band circumferences to improve collar fit across time. We propose implementation of iterative processes in collar design, including a preliminary Phase I that utilizes captive animals to test initial collar designs, a subsequent Phase II that incorporates modifications to initial collar designs and further testing in captivity, and Phase III as a limited pilot deployment in a field study.
Drones are growing in popularity and are used to locate individual animals, estimate ungulate population size, and monitor endangered species. Our goal was to assess the efficacy of using drones to ...locate neonatal white-tailed deer (Odocoileus virginianus) for capture. During May–June 2019 and June 2020, we used a drone equipped with thermal-infrared (TIR) and conventional multispectral red-green-blue (RGB) cameras to locate and confirm fawn thermal signatures in Minnesota’s southern farmland region. We confirmed 29 and 71 fawn thermal signatures in 2019 and 2020, respectively. We captured 13 fawns to validate the methodology (detection and identification) of using drones for capture in 2019. We flew the drone for 47.3 hours covering 792 hectares (17 hectares per hour) in 2019 and flew for 41.1 hours and covered 1640 hectares (40 hectares per hour) in 2020. We worked 201.5 person-hours with a mean crew size of 4 people that required 6.9 person-hours to locate each fawn in 2019, whereas we worked 145.7 person-hours with a mean crew size of 4 people that required 70% less effort and resulted in 2.1 person-hours to locate each fawn in 2020. Flight efficiency was highest at 60m above ground level (AGL) with a speed of 9 m/s; however, diurnal use of drones made identifying fawn thermal signatures difficult as thermal loading of the environment quickly reduced the temperature differential between vegetation and signatures. We found TIR-equipped drones to be an efficient method to locate and subsequently capture fawns in open habitats in comparison to other capture methods such as vaginal implant transmitters (VITs), ground searches, or monitoring doe behavior. We recommend flying at night or in cloudy conditions to avoid false positives.
The coyote (Canis latrans) is a recent addition to the fauna of eastern North America, and in many areas coyote populations have been established for only a decade or two. Although coyotes are known ...predators of white-tailed deer (Odocoileus virginianus) in their historic range, effects this new predator may have on eastern deer populations have received little attention. We speculated that in the southeastern United States, coyotes may be affecting deer recruitment, and we present 5 lines of evidence that suggest this possibility. First, the statewide deer population in South Carolina has declined coincident with the establishment and increase in the coyote population. Second, data sets from the Savannah River Site (SRS) in South Carolina indicate a new mortality source affecting the deer population concurrent with the increase in coyotes. Third, an index of deer recruitment at SRS declined during the period of increase in coyotes. Fourth, food habits data from SRS indicate that fawns are an important food item for coyotes during summer. Finally, recent research from Alabama documented significant coyote predation on fawns there. Although this evidence does not establish cause and effect between coyotes and observed declines in deer recruitment, we argue that additional research should proactively address this topic in the region. We identified several important questions on the nature of the deer–coyote relationship in the East.
Many studies have documented that coyotes (Cams latrans) are the greatest source of natural mortality for white-tailed deer (Odocoileus virginianus) neonates (< 3 months old). With the range ...expansion of coyotes eastward in North America, many stakeholders are concerned that coyote prédation may be affecting deer populations adversely. We hypothesized that declines in neonate survival, perhaps caused by increasing coyote prédation, could be offset by adjusting or eliminating antlerless harvest allocations. We used a stochastic, age-based population simulation model to evaluate combinations of low neonate survival rates, severe winters, and low adult deer survival rates to determine the effectiveness of reduced antlerless harvest at stabilizing deer populations. We found that even in regions with high winter mortality, reduced antlerless harvest rates could stabilize deer populations with recruitment and survival rates reported in the literature. When neonate survival rates were low (25%) and yearling and adult female survival rates were reduced by 10%, elimination of antlerless harvests failed to stabilize populations. Our results suggest increased deer mortality from coyotes can be addressed through reduced hunting harvest of adult female deer in most circumstances throughout eastern North America. However, specific knowledge of adult female survival rates is important for making management decisions in areas where both neonate and adult survival may be affected by prédation and other mortality factors.
The reproductive season of white-tailed deer (Odocoileus virginianus) has been hypothesized to be aseasonal south of about 14°–18°N latitude, where annual variation in day length is low. We tested ...this idea by using camera-trap data (1,336 photographed individuals identified by age and sex) collected during 2011–2017 in the dry tropical forest of Santa Rosa National Park, northwest Costa Rica, where wet and dry seasons are well-defined. We identified variation in monthly occurrence of spotted deer fawns, as well as the status of antler growth of male deer, specifically related to the very seasonal environment of the region. Year-round reproduction likely occurs, but the rainfall pattern in the area greatly influences the relative frequency of reproductive indicators, with most births occurring during the dry season, and a second peak occurring toward the latter part of the wet season. We speculate that food resources are the major influence on reproductive patterns, and that variation in types and timing of food resource availability likely account for the variation in reproductive patterns.
Despite their importance for understanding predator–prey interactions, factors that affect predator evasion behaviours of offspring of large ungulates are poorly understood. Our objective was to ...characterize the influence of selection and availability of escape cover and maternal presence on predator evasion by white-tailed deer, Odocoileus virginianus, fawns in the northern Great Plains, U.S.A. We observed 45 coyote, Canis latrans, chases of fawns, and we participated in 83 human chases of fawns during 2007–2009, of which, 19 and 42 chases, respectively, ended with capture of the fawn. Evasive techniques used by fawns were similar for human and coyote chases. Likelihood of a white-tailed deer fawn escaping capture, however, was influenced by deer group size and a number of antipredator behaviours, including aggressive defence by females, initial habitat and selection of escape cover, all of which were modified by the presence of parturient females. At the initiation of a chase, fawns in grasslands were more likely to escape, whereas fawns in forested cover, cultivated land or wheat were more likely to be captured by a coyote or human. Fawns fleeing to wetlands and grasslands also were less likely to be captured compared with those choosing forested cover, wheat and cultivated land. Increased probability of capture was associated with greater distance to wetland and grassland habitats and decreased distance to wheat. Use of wetland habitat as a successful antipredator strategy highlights the need for a greater understanding of the importance of habitat complexity in predator avoidance.
► Likelihood of a white-tailed deer fawn escaping capture was influenced by selection of escape cover. ► At the initiation of a chase, fawns in grasslands were more likely to escape. ► Fawns in forested cover, cultivated land or wheat were more likely to be captured. ► Fawns accompanied by does bypassed nearest concealment cover and proceeded to wetland habitats. ► Probability of capture was associated with distance to wetlands, grasslands and wheat.
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