EFFECT OF RACCOON (PROCYON LOTOR) REDUCTION ON BLANDING’S TURTLE (EMYDOIDEA BLANDINGII) NEST SUCCESS

The Lake County Forest Preserve District has monitored a state-endangered Blanding’s Turtle (Emydoidea blandingii) population at two adjoining nature preserves along the Illinois–Wisconsin border since 2004. Prior to predator management, 92.3% of documented and unprotected natural Blanding’s Turtle nests (12 of 13) and 88% of monitored artificial nests have been at least partially depredated. The goal of this study was to determine the efficacy of subsidized Raccoon (Procyon lotor) removal efforts in increasing the nest success of Blanding’s Turtles. During April–May 2013 and 2014, we captured and euthanized 78 Raccoons from our 2 km2 study area. We estimated pre-removal abundance estimates using the Leslie depletion method; it appeared that we removed 83–89% of the Raccoons from the study area each year and pre-removal density estimates were 37.5% lower in 2014 than 2013. During the study period, we monitored 22 Blanding’s Turtle in situ unprotected nests. In 2013, one of seven (14%) Blanding’s Turtle nests was partially depredated and no nests were completely depredated, indicative of a successful impact of Raccoon removal on Blanding’s Turtle nest success. However in 2014, nine of 15 (60%) Blanding’s Turtle nests were depredated. Our results provide some evidence that removal of Raccoons may have increased Blanding’s Turtle nest success but other factors, such as a functional response of surviving Raccoons or depredation by other subsidized predators may be contributing to decreased nest success

Asian Carp in the Diet of River Otters in Illinois

Populations of invasive silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis), collectively known as “Asian carp,” are growing rapidly in Illinois and may make up a large fraction of available prey for river otters (Lontra canadensis) in larger waterbodies. Our goals were to assess the frequency of Asian carp in otter diets and compare the frequency of occurrence of prey groups (fish, crayfish, and amphibians) in otter diets between land cover types and seasons. We searched for Asian carp otoliths and pharyngeal teeth, as well as parts of other fishes, crayfish, and amphibians in 155 otter scats collected from 43 stream sites in central and southern Illinois during January-April 2013 and 2014. Consistent with previous studies, fish and crayfish were primary prey items for otters, followed by amphibians. Frequency of occurrence of crayfish increased from January-February to March-April, but frequency of occurrence of the other prey types remained similar between those periods. Land cover type did not seem to influence frequency of occurrence of prey types. Asian carp pharyngeal teeth and otoliths occurred in four (2.6%) scat samples, two from sites were Asian carp were not previously confirmed to be present. This is the first direct confirmation of Asian carp in the diet of wild river otters. Otoliths and pharyngeal teeth provided effective structures for identifying fish species in otter diet

Use of Snares to Live-Capture Beavers

Wildlife managers, researchers, and nuisance-control operators often require a nonlethal means of capturing beavers (Castor canadensis). Historically, live-capture has relied on enclosure-type traps such as Bailey or Hancock traps. We describe the live-capture of 231 beavers using snares in southern Illinois from 2002 to 2005. Capture success averaged 5.4 beavers/100 trap-nights. Capture success did not differ between sexes (P = 0.57) or age-classes (P = 0.68). We captured most beavers in haul-out slide sets, surface run sets, or channel sets. Recaptures accounted for 28% (n = 65) of all captures. Mortality rate using snares was 10% and decreased annually during the study period. Snares are advantageous over enclosure-type traps because they have a high capture:cost ratio and are less heavy and cumbersome than traps. However, mortality rates are relatively high, limiting the utility of this technique for some research

Survival and Dispersal of White-tailed Deer in the Agricultural Landscape of East-central Illinois

White-tailed deer (Odocoileus virginianus) are a keystone species throughout their range in North America. The recent presence of diseases such as chronic wasting disease and bovine tuberculosis in Midwestern North America dictates the examination of influences of those diseases on deer populations, and survival and dispersal rates are important parameters when modeling potential disease spread. We quantified survival and dispersal rates of 105 deer in agriculturally-dominated east-central Illinois during 2005-2009. We used Program MARK to estimate rates of annual survival, seasonal survival, and dispersal for fawn, yearling, and adult age-classes. Male and female seasonal (winter/spring [16 Dec–14 May], summer [15 May–30 Sep], and fall/winter [1 Oct–15 Dec]) survival ranged from 0.56-0.95 and 0.84-0.96, respectively. Male survival was lower than female survival during the fall/winter season. Dispersal rates for yearling and fawn males and yearling and fawn females were 0.44 ± 0.07 and 0.41 ± 0.07, respectively. The dispersal rate of adult males was 0.46 ± 0.15 and no adult females dispersed. Deer survival appears to be higher than previously reported in the region, with important implications for potential disease spread. Furthermore, the observation of long-distance dispersal (42–96 km) combined with greater estimates of survival may impact current chronic wasting disease modeling efforts

Spatial and Temporal Analysis of Contact Rates in Female White-Tailed Deer

White-tailed deer (Odocoileus virginianus) are important game mammals and potential reservoirs of diseases of domestic livestock; thus, diseases of deer are of great concern to wildlife managers. Contact, either direct or indirect, is necessary for disease transmission, but we know little about the ecological contexts that promote intrasexual contact among deer. Using pair-wise direct contacts estimated from Global Positioning System collar locations and joint utilization distributions (JUDs), we assessed habitats in which contacts occur to test whether direct contact rates among female white-tailed deer in different social groups differs among land-cover types. We also tested whether contact rates differed among seasons, lunar phases, and times of day. We obtained locations from 27 female deer for periods of 0.5–17 months during 2002–2006. We designated any simultaneous pair of locations for 2 deer ,25 m apart as a direct contact. For each season, we used compositional analysis to compare land-cover types where 2 deer had contact to available land-cover weighted by their JUD. We used mixedmodel logistic regression to test for effects of season, lunar phase, and time of day on contact rates. Contact rates during the gestation season were greater than expected from random use in forest and grassland cover, whereas contact rates during the fawning period were greater in agricultural fields than in other land-cover types. Contact rates were greatest during the rut and lowest in summer. Diel patterns of contact rates varied with season, and contact rates were elevated during full moon compared to other lunar periods. Both spatial and temporal analyses suggest that contact between female deer in different social groups occurs mainly during feeding, which highlights the potential impact of food distribution and habitat on contact rates among deer. By using methods to associate contacts and land-cover, we have created beneficial tools for more elaborate and detailed studies of disease transmission. Our methods can offer information necessary to develop spatially realistic models of disease transmission in deer

Survival and Dispersal of White-tailed Deer in the Agricultural Landscape of East-central Illinois

White-tailed deer (Odocoileus virginianus) are a keystone species throughout their range in North America. The recent presence of diseases such as chronic wasting disease and bovine tuberculosis in Midwestern North America dictates the examination of influences of those diseases on deer populations, and survival and dispersal rates are important parameters when modeling potential disease spread. We quantified survival and dispersal rates of 105 deer in agriculturally-dominated east-central Illinois during 2005-2009. We used Program MARK to estimate rates of annual survival, seasonal survival, and dispersal for fawn, yearling, and adult age-classes. Male and female seasonal (winter/spring [16 Dec–14 May], summer [15 May–30 Sep], and fall/winter [1 Oct–15 Dec]) survival ranged from 0.56-0.95 and 0.84-0.96, respectively. Male survival was lower than female survival during the fall/winter season. Dispersal rates for yearling and fawn males and yearling and fawn females were 0.44 ± 0.07 and 0.41 ± 0.07, respectively. The dispersal rate of adult males was 0.46 ± 0.15 and no adult females dispersed. Deer survival appears to be higher than previously reported in the region, with important implications for potential disease spread. Furthermore, the observation of long-distance dispersal (42–96 km) combined with greater estimates of survival may impact current chronic wasting disease modeling efforts

Familiarity Breeds Contempt: Combining Proximity Loggers and GPS Reveals Female White-tailed Deer (Odocoileus virginianus) Avoiding Close Contact With Neighbors

Social interactions can influence infectious disease dynamics, particularly for directly transmitted pathogens. Therefore, reliable information on contact frequency within and among groups can better inform disease modeling and management. We compared three methods of assessing contact patterns: (1) space-use overlap (volume of interaction [VI]), (2) direct contact rates measured by simultaneous global positioning system (GPS) locations (apart), and (3) direct contact rates measured by proximity loggers (PLs; 1-m detection) among female white-tailed deer (Odocoileus virginianus). We calculated the PL∶GPS contact ratios to see whether both devices reveal similar contact patterns and thus predict similar pathogen transmission patterns. Contact rates measured by GPS and PLs were similarly high for two within-group dyads (pairs of deer in the same social groups). Dyads representing separate but neighboring groups (high VI) had PL∶GPS contact ratios near zero, whereas dyads further apart (intermediate VI) had higher PL∶GPS contact ratios. Social networks based on PL contacts showed the fewest connected individuals and lowest mean centrality measures; network metrics were intermediate when based on GPS contacts and greatest when based on VI. Thus, the VI network portrayed animals to be more uniformly and strongly connected than did the PL network. We conclude that simultaneous GPS locations, compared with PLs, substantially underestimate the impact of group membership on direct contact rates of female deer and make networks appear more connected. We also present evidence that deer coming within the general vicinity of each other are less likely to come in close contact if they are in neighboring social groups than deer whose home ranges overlap little if at all. Combined, these results provide evidence that direct transmission of disease agents among female and juvenile white-tailed deer is likely to be constrained both spatially and by social structure, more so than GPS data alone would suggest

Effects of Joint Space Use and Group Membership on Contact Rates Among White-Tailed Deer

Establishment and spread of infectious diseases are controlled by the frequency of contacts among hosts. Although managers can estimate transmission coefficients from the relationship between disease prevalence and age or time, they may wish to quantify or compare contact rates before a disease is established or while it is at very low prevalence. Our objectives were to quantify direct and indirect contacts rates among white-tailed deer (Odocoileus virginianus) and to compare these measures of contact rate with simpler measures of joint space use. We deployed Global Positioning System (GPS) collars on 23 deer near Carbondale, Illinois, USA, from 2002 to 2005. We used location data from the GPS collars to measure pairwise rates of direct and indirect contact, based on a range of proximity criteria and time lags, as well as volume of intersection (VI) of kernel utilization distributions. We analyzed contact rates at a given distance criterion and time lag using mixed-model logistic regression. Direct contact rates increased with increasing VI and were higher in autumn–spring than in summer. After accounting for VI, the estimated odds of direct contact during autumn–spring periods were 5.0–22.1-fold greater (depending on the proximity criterion) for pairs of deer in the same social group than for between-group pairs, but for direct contacts during summer the within:between-group odds ratio did not differ significantly from 1. Indirect contact rates also increased with VI, but the effects of both season and pair-type were much smaller than for direct contacts and differed little as the time lag increased from 1–30 days. These results indicate that simple measures of joint space use are insufficient indices of direct contact because group membership can substantially increase contacts at a given level of joint space use. With indirect transmission, however, group membership had a much smaller influence after accounting for VI. Relationships between contact rates and season, VI, and pair-type were generally robust to changes in the proximity criterion defining a contact, and patterns of indirect contacts were affected little by the choice of time lag from 1–30 days. The use of GPS collars provides a framework for testing hypotheses about the form of contact networks among large mammals and comparing potential direct and indirect contact rates across gradients of ecological factors, such as population density or landscape configuration

Record of a Sixteen-year-old White-tailed Deer (Odocoileus virginianus) in Carbondale, Illinois: a Brief Note.

In May 2004, a dead white-tailed deer (Odocoileus virginianus) radiocollared in 1991 was found in Carbondale, Illinois, and was aged at 16 years old via cementum annuli analysis. She was a member of an unharvested, free-ranging population and likely died of natural causes. Given the average longevity of deer in unharvested populations at about 8 years of age, our finding is quite rare. Increased longevity of deer can heighten lifetime reproductive output, which may contribute to elevated deer abundance and concentrated herbivory in urban settings