Olin E. Rhodes

A Hierarchical Analysis of Habitat Selection by Raccoons in Northern Indiana

Abstract Although numerous studies have examined habitat use by raccoons (Procyon lotor), information regarding seasonal habitat selection related to resource availability in agricultural landscapes is lacking for this species. Additionally, few studies using radiotelemetry have investigated habitat selection at multiple spatial scales or core-use areas by raccoons. We examined seasonal habitat selection of 55 (31 M, 24 F) adult raccoons at 3 hierarchical orders defined by the movement behavior of this species (second-order home range, second-order core-use area, and third-order home range) in northern Indiana, USA, from May 2003 to June 2005. Using compositional analysis, we assessed whether habitat selection differed from random and ranked habitat types in order of selection during the crop growing period (season 1) and corn maturation period (season 2), which represented substantial shifts in resource availability to raccoons. Habitat rankings differed across hierarchical orders, between seasons within hierarchical orders, and between sexes within seasons; however, seasonal and intersexual patterns of habitat selection were not consistent across hierarchical orders of spatial scale. When nonrandom utilization was detected, both sexes consistently selected forest cover over other available habitats. Seasonal differences in habitat selection were most evident at the core-area scale, where raccoon selection of agricultural lands was highest during the maturation season when corn was available as a direct food source. Habitat use did not differ from availability for either sex in either season at the third-order scale. The selection of forest cover across both seasons and all spatial orders suggested that raccoon distribution and abundance in fragmented landscapes is likely dependent on the availability and distribution of forest cover, or habitats associated with forest (i.e., water), within the landscape. The lack of consistency in habitat selection across hierarchical scales further exemplifies the need to examine multiple biological scales in habitat-selection studies.

Home-Range Attributes of Raccoons in a Fragmented Agricultural Region of Northern Indiana

Abstract For many wildlife species, agricultural landscapes undergo spatial and temporal fluctuations in the composition of food and cover annually with the planting and harvesting of crops. Raccoon (Procyon lotor) populations have flourished in agricultural landscapes, where crops increase foraging opportunities and efficiencies. However, information is lacking regarding the effects of temporal shifts in food and cover resulting from agricultural activities on raccoon home ranges. We examined home-range characteristics of 60 (33 M, 27 F) adult raccoons in northern Indiana, USA, from May 2003 through June 2005 to identify shifts in the size of home ranges and core use areas among seasons defined by crop availability and crop developmental stages. Mean fixed-kernel home-range (92 ± 6 ha; 𝑥̄ ± SE) and core-area sizes (20 ± 2 ha) of males were significantly larger than those of females (58 ± 7 ha and 13 ± 2 ha, respectively), and both were smaller than those reported for raccoons in other fragmented agricultural landscapes. Home-range sizes varied little among seasons for either sex. However, home ranges of males were smallest during the crop maturation stage, whereas home ranges of females were smallest during the crop growing season. The results of our study suggest that even in expansive rural landscapes, raccoons can maintain small home ranges when food, water, and denning resources are readily available. Additionally, the lack of differences among seasonal home-range sizes, despite the presence of an ephemeral superabundant food source (i.e., corn) during the maturation season, was likely due to the close proximity of foraging and denning resources across seasons.

ASSESSMENT OF GENETIC VARIANCE AMONG SOURCE AND REINTRODUCED FISHER POPULATIONS

Abstract A series of reintroduction programs have reestablished fisher (Martes pennanti) populations to a large part of their former range. Horizontal starch-gel electrophoresis of 20 presumptive gene loci was used from 1996 to 1998 to investigate gene dynamics in 4 remnant fisher populations (sources) and 4 reintroduced fisher populations from the northeastern and Great Lakes regions of the United States. Mean multilocus heterozygosities, mean number of alleles per locus, and percentage polymorphic loci were 0.027–0.090, 1.2–1.6, and 10.0–30.0, respectively, in the 8 populations surveyed. Significant allelic frequency differentiation was detected among the 4 source populations and among the 4 reintroduced populations, but a significant proportion of the genetic variance was partitioned only among the 4 reintroduced populations. Pairwise comparisons between each source and its associated reintroduced population indicated that only older reintroductions have attained significant differentiation of allelic frequency from their sources. Significant heterozygotic deficiencies were detected for statewide populations and regional populations within states, suggesting that breeding biology of the fisher, presumably among females, is creating levels of fine-scale genetic structure within populations.

Assessing Hybridization in Wildlife Populations Using Molecular Markers: A Case Study in Wild Turkeys

Abstract Extensive translocation of wildlife throughout North America has led to concerns regarding taxonomic integrity for a number of species. Often, multiple subspecies or variants were translocated into a common habitat or region, creating the opportunity for hybridization to occur. This issue is of particular concern to managers of wild turkeys (Meleagris gallopavo), a species in which considerable mixing of subspecies has occurred. We aim to quantify the subspecific status and degree of hybridization of individuals within an introduced population of Merriams turkeys (M. g. merriami) in the Davis Mountains of Texas, USA, and within nearby Rio Grande turkey populations (M. g. intermedia). We used data from the Merriams source population in New Mexico, USA, as a baseline reference for the genetic characteristics of the Merriams subspecies. Nineteen years following the introduction event, microsatellite data indicate that the genetic integrity of the introduced population of Merriams turkeys in the Davis Mountains Preserve has been eroded by both immigration from and hybridization with nearby Rio Grande populations. Data from the mitochondrial control region allow for further characterization of hybrid individuals and indicate that most hybrids were the result of immigrant Rio Grande males mating with resident Merriams females. Our results attribute to the potential importance of hybridization in wildlife species and suggest that hybridization can be a rapid process capable of drastically altering the evolutionary integrity of animals in a region.

FLIGHT BEHAVIOR OF BLACK AND TURKEY VULTURES: IMPLICATIONS FOR REDUCING BIRD–AIRCRAFT COLLISIONS

Abstract Mid-air collisions with black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) regularly cause substantial damage to military and civilian aircraft. Information concerning the flight behavior of black and turkey vultures potentially could improve predictive models designed to reduce bird strikes by aircraft. We examined the flight behavior of black and turkey vultures at the Savannah River Site (SRS) in South Carolina, USA, and determined whether flight characteristics were predictable with respect to weather and time variables. We captured birds at their primary roost and subsequently relocated them via aerial telemetry from 11 February 2002 through 29 January 2003. One hundred eighty of 326 locations (55%) for 8 black vultures and 129 of 206 locations (63%) for 5 turkey vultures were of flying birds. Black vultures flew at an average altitude of 169 ± 115 (SD) m above ground level, whereas turkey vulture flight altitude averaged 163 ± 92 m. Our results contrast with those of previous studies that reported less frequent and lower altitude flights. The flight behavior of both species appeared to be influenced minimally by weather and time variables. However, we were unable to construct useful models predicting aspects of flight behavior using the variables we measured (all models had R2 or pseudo R2 values <0.10). We suggest that other factors, such as food availability, inter- and intra-specific interactions, and physiological demands play a larger role in vulture flight behavior than the variables we measured. Our results suggest that the development of bird avoidance strategies by aircraft operators should consider the variability of flight behaviors of black and turkey vultures across their ranges. Future research emphases should shift from examinations of the effects of local conditions on flight behavior to the elucidation of factors contributing to differences in flight behavior among regions.

HOME RANGES OF SYMPATRIC BLACK AND TURKEY VULTURES IN SOUTH CAROLINA

Abstract We examined home-range characteristics of seven Black Vultures (Coragyps atratus) and four Turkey Vultures (Cathartes aura) at the Savannah River Site, South Carolina. Birds were captured at their primary roost and tracked via aerial telemetry from 11 February 2002 through 29 January 2003. Mean annual home-range sizes (95% fixed kernel) for Black and Turkey Vultures were 12 399 ± 5199 ha [SE] and 34 053 ± 8567 ha, respectively. Black Vultures concentrated their movements around the primary roost, whereas Turkey Vultures demonstrated less site fidelity. Home-range sizes and time spent soaring for both species were much greater than reported for vultures residing in an agricultural landscape. We suggest that food resources at the heavily forested Savannah River Site were fewer and less predictable than in agricultural landscapes, requiring larger home ranges and increased time spent foraging. Rangos de Hogar de los Buitres Simpátricos Coragyps atratus y Cathartes aura en Carolina del Sur Resumen. Examinamos las características de los rangos de hogar de siete Coragyps atratus y cuatro Cathartes aura en Savannah River, Carolina del Sur. Las aves fueron capturadas en sus sitios de descanso principales y fueron rastreadas mediante telemetría aé rea desde el 11 de febrero de 2002 hasta el 29 de enero de 2003. Los tamaños medios de rango de hogar (kernel fijo del 95%) fueron de 12 399 ± 5199 ha [EE] para C. atratus y de 34 053 ± 8567 ha para C. aura. Cathartes atratus concentró sus movimientos alrededor de sus sitios de descanso principales, mientras que C. aura demostró menor fidelidad al sitio. Para las dos especies, los tamaños del rango de hogar y el tiempo que permanecieron planeando fueron mucho mayores que los reportados para buitres que habitan paisajes agrícolas. Sugerimos que en Savannah River, un sitio con alta cobertura forestal, los recursos alimenticios eran más escasos y menos predecibles que en paisajes agrícolas, requiriendo rangos de hogar mayores y un incremento en el tiempo de forrajeo.

A robust set of black walnut microsatellites for parentage and clonal identification

We describe the development of a robust and powerful suite of 12 microsatellite marker loci for use in genetic investigations of black walnut and related species. These 12 loci were chosen from a set of 17 candidate loci used to genotype 222 trees sampled from a 38-year-old black walnut progeny test. The 222 genotypes represent a sampling from the broad geographic distribution of the species. Analysis of the samples using the 12 loci revealed an average expected heterozygosity of 0.83, a combined probability of identity of 3×10−19, and a combined probability of exclusion for paternity analysis of >0.999. The 222 genotyped trees from the progeny test comprised 39 open-pollinated families, 29 of which (having at least five sampled progeny) were used to estimate the outcrossing rate for the progeny trial. The same 29 families were used to construct a Neighbor-Joining dendrogram based upon allele sharing between individuals. The multilocus estimate of the outcrossing rate was 100% (standard error of zero), higher than the 90% level found in previous studies at the embryo stage, suggesting that both artificial and natural selection against selfs may have occurred over the 38-year lifespan of the progeny trial. In the Neighbor-Joining dendrogram, the majority of the putative siblings grouped together in 21 out of the 29 families, showing that the microsatellites were able to discern most of the family structure in the dataset. Our results indicate that errors were sometimes committed during the establishment of the progeny test. This set of microsatellite loci clearly provides a powerful tool for future applications in black walnut.

GENETIC CONSEQUENCES OF REINTRODUCTIONS: AN EXAMPLE FROM OREGON PRONGHORN ANTELOPE (ANTILOCAPRA AMERICANA)

Abstract In 1969, 17 pronghorn were reintroduced onto Umatilla Army Base in Oregon with no subsequent translocations or immigration into this fully enclosed area. We explored the genetic signature this event left on the population using a combination of microsatellite genotypes and mitochondrial DNA (mtDNA) sequencing data of this population. We compared the present day Umatilla herd to its source population and to a southeastern Oregon population. We found the reintroduced population had sharply lower genetic diversity compared to its source despite its rapid increase in population size following the initial founding event. It is likely the observed loss of diversity and the significant differentiation observed between the Umatilla herd and its source was a function of the low number of founders and stochastic losses of diversity in subsequent generations. We observed significant haplotypic and genotypic differentiation between the reintroduced population and its source (GST = 0.063, FST = 0.078, p < 0.001) that was approximately 3.5 times that found between the source and the southeastern population (GST = 0.018, FST = 0.021, p < 0.001). Moreover, 2 rare alleles in the source population were found in high frequency in the translocated population. The founding effect, stochastic shifts in allele frequencies each generation, restricted gene flow, and variance in the segregation of alleles related to a polygamous mating system have contributed to the significant differentiation observed between the Umatilla herd and its source. The results of this study can be applied directly to the management of ongoing translocation activities within Oregon.

Genetic Evaluation of the Lake Sturgeon Reintroduction Program in the Mississippi and Missouri Rivers

Abstract Over the past 20 years, there has been a growing awareness of the impact of genetic factors on the success of reintroduction programs for fish and other species. One primary genetic criterion to be considered in the design and implementation of reintroduction programs is the maximization of genetic diversity within reintroduced populations. Reintroduction has become an important management tool for the imperiled lake sturgeon Acipenser fulvescens. However, little published work has evaluated current lake sturgeon reintroduction programs in terms of their ability to transfer genetic diversity from source populations to reintroduced populations. We evaluated the success of an ongoing lake sturgeon reintroduction program based upon its ability to adequately transmit the genetic diversity of the Lake Winnebago source population into reintroduced populations in the Mississippi and Missouri rivers. Additionally, a nonreintroduced single year-class from a hatchery population established from the Lake Wi...

Hybrid swarm between divergent lineages of mule deer (Odocoileus hemionus)

Studies of hybrid zones have revealed an array of evolutionary outcomes, yet the underlying structure is typically characterized as one of three types: a hybrid zone, a hybrid swarm or a hybrid taxon. Our primary objective was to determine which of these three structures best characterizes a zone of hybridization between two divergent lineages of mule deer (Odocoileus hemionus), mule deer and black‐tailed deer. These lineages are morphologically, ecologically and genetically distinct, yet hybridize readily along a zone of secondary contact between the east and west slopes of the Cascade Mountains (Washington and Oregon, USA). Using microsatellite and mitochondrial DNA, we found clear evidence for extensive hybridization and introgression between lineages, with varying degrees of admixture across the zone of contact. The pattern of hybridization in this region closely resembles a hybrid swarm; based on data from 10 microsatellite loci, we detected hybrids that extend well beyond the F1 generation, did not detect linkage disequilibrium at the centre of the zone and found that genotypes were associated randomly within the zone of contact. Introgression was characterized as bidirectional and symmetric, which is surprising given that the zone of contact occurs along a sharp ecotone and that lineages are characterized by large differences in body size (a key component of mating success). Regardless of the underlying mechanisms promoting hybrid swarm maintenance, it is clear that the persistence of a hybrid swarm presents unique challenges for management in this region.