Philip S. Gipson

Accuracy and precision of estimating age of gray wolves by tooth wear

We evaluated the accuracy and precision of tooth wear for aging gray wolves (Canis lupus) from Alaska, Minnesota, and Ontario based on 47 known-age or known-minimum-age skulls. Estimates of age using tooth wear and a commercial cementum annuli-aging service were useful for wolves up to 14 years old. The precision of estimates from cementum annuli was greater than estimates from tooth wear, but tooth wear estimates are more applicable in the field. We tended to overestimate age by 1-2 years and occasionally by 3 or 4 years. The commercial service aged young wolves with cementum annuli to within ±1 year of actual age, but under estimated ages of wolves ≥9 years old by 1-3 years. No differences were detected in tooth wear patterns for wild wolves from Alaska, Minnesota, and Ontario, nor between captive and wild wolves. Tooth wear was not appropriate for aging wolves with an underbite that prevented normal wear or severely broken and missing teeth.

DO MELANIN- OR CAROTENOID-PIGMENTED PLUMAGE ORNAMENTS SIGNAL CONDITION AND PREDICT PAIRING SUCCESS IN THE KENTUCKY WARBLER?

Abstract Yellow and red feathers pigmented by carotenoids can signal a birds condition and are important to both female choice and male-male competition. Melanin-based ornaments are thought to be less effective than carotenoid ornaments as indicators of condition, though their signal function is still relatively unstudied. We examined both carotenoid and melanin-pigmented feather ornaments in a single species, the Kentucky Warbler (Oporornis formosus). Both males and females of this species have melanin-pigmented ornamentation (black crown, black face) and carotenoid-pigmented ornamentation (lemon-yellow undersides). Melanin-pigmented plumage patches were larger in males than females, and males had brighter breast plumage, with a larger ultraviolet component, than females. Among males in the wild, individuals in better condition had more extensive black caps and faces, but not brighter-yellow breasts. Males with larger black caps were more likely to attract mates. This work demonstrates that, in a species with both melanin- and carotenoid-pigmented plumage, melanin-pigmented ornaments can signal condition, and that a melanin-based signal can explain variance in mating success. ¿Funcionan Como Indicadores de la Condición Física y Predicen del Éxito de Apareamiento los Ornamentos del Plumaje Pigmentados con Melanina o Carotenoides en Oporornis formosus? Resumen. Las plumas amarillas y rojas pigmentadas por carotenoides pueden indicar la condición de un ave y son importantes tanto para la elección de machos por parte de las hembras como para la competencia entre machos. Se cree que los ornamentos a base de melanina son menos efectivos como indicadores de condición que los ornamentos carotenoides, aunque su función como señal ha sido menos estudiada. Examinamos plumas ornamentales pigmentadas con carotenoides y melanina en la especie Oporornis formosus. Tanto el macho como la hembra presentan ornamentación pigmentada con melanina (corona negra, rostro negro) y ornamentación pigmentada con carotenoides (flancos inferiores amarillo-limón). Los parches de plumaje pigmentados con melanina fueron mayores en los machos que en las hembras y el plumaje del pecho de los machos fue más brillante y con un componente ultravioleta mayor que el de las hembras. Entre los machos en ambiente natural, los individuos con mejor condición tuvieron coronas y rostros negros más extensos, pero no tuvieron pechos amarillos más brillantes. Los machos con coronas negras más extensas tuvieron una mayor probabilidad de atraer parejas. Este trabajo demuestra que en una especie con plumaje pigmentado con melanina y carotenoides, los ornamentos pigmentados con melanina pueden señalar la condición de los individuos, y que una señal con base en melanina puede explicar la varianza en el éxito reproductivo.

Food Habits of Coyotes in Arkansas

Stomach contents from 168 coyotes (Canis latrans) collected in Arkansas from July 1969 through January 1974 were analyzed. The 11 most common food items and percent occurrence, shown in parentheses, were: poultry (34), persimmons (23), insects (11), rodents (9), songbirds (8), cattle (7), rabbits (7), deer (5), woodchucks (4), goats (4), and watermelons (4). J. WILDL. MANAGE. 38(4):848-853 Coyote food habits have been extensively studied over their original western range. These studies considered annual food habits over broad geographical areas encompassing one or more states (Sperry 1941, Ferrel et al. 1953, Fichter et al. 1955, Korschgen 1957, Gier 1968) and regional ones relating to smaller areas such as National Parks and portions of states (Murie 1935 and 1940, Murie 1951, Bond 1939, Ellis 1959, Knowlton 1964, Hawthorne 1972). Other studies concerned specific seasons (Ozoga and Harger 1966) or pegleg coyotes (Sperry 1939). Only three food habit studies have been made in areas recently invaded by coyotes (Fooks 1961, Ozoga and Harger 1966, Wilson 1967) and they include only small numbers of specimens or material from a single

Evaluation of a reproductive index to estimate dickcissel reproductive success

Intensive monitoring of bird nests to measure reproductive success is time-consuming and may influence the fate of nests. Reproductive indices that do not require searching for and visiting nests may be reasonable alternatives to nest monitoring if they provide results similar to nest-searching efforts. We evaluated the reproductive index of Vickery et al. (1992) for estimating reproductive success of the dickcissel (Spiza americana) in northeast Kansas, USA. We used nest searching and Vickery et al.s (1992) reproductive index to compare reproductive success on 20 plots (200 x 200 m). Daily nest survival (DNS) rates averaged 0.911 (SE = 0.011, n = 72 nests), and brown-headed cowbirds (Molothrus ater) accounted for 21% of all nest failures. Surveyors underestimated reproductive index ranks when compared to nest-searching efforts and were inaccurate in their assignment of reproductive success. In particular, surveyors reported successful nests on 3 study plots that fledged no young, probably because young dickcissels moved onto plots after fledging from their natal territories. Our results indicate that the reproductive index of Vickery et al. (1992) may be inappropriate for wary species or those heavily parasitized by brood parasites. We suggest that before relying on the index alone, investigators should use pilot trials to determine whether results from this index are concordant with results from intensive nest-searching efforts for species of interest.

Factors affecting detectability of river otters during sign surveys

ABSTRACT Sign surveys are commonly used to study and monitor wildlife species but may be flawed when surveys are conducted only once and cover short distances, which can lead to a lack of accountability for false absences. Multiple observers surveyed for river otter (Lontra canadensis) scat and tracks along stream and reservoir shorelines at 110 randomly selected sites in eastern Kansas from January to April 2008 and 2009 to determine if detection probability differed among substrates, sign types, observers, survey lengths, and near access points. We estimated detection probabilities (p) of river otters using occupancy models in Program PRESENCE. Mean detection probability for a 400-m survey was highest in mud substrates (p = 0.60) and lowest in snow (p = 0.18) and leaf litter substrates (p = 0.27). Scat had a higher detection probability (p = 0.53) than tracks (p = 0.18), and experienced observers had higher detection probabilities (p > 0.71) than novice observers (p < 0.55). Detection probabilities increased almost 3-fold as survey length increased from 200 m to 1,000 m, and otter sign was not concentrated near access points. After accounting for imperfect detection, our estimates of otter site occupancy based on a 400-m survey increased >3-fold, providing further evidence of the potential negative bias that can occur in estimates from sign surveys when imperfect detection is not addressed. Our study identifies areas for improvement in sign survey methodologies and results are applicable for sign surveys commonly used for many species across a range of habitats.

Diets of free-ranging mexican gray wolves in arizona and New Mexico

Abstract Systematic diet studies of Mexican gray wolves (Canis lupus baileyi) were not conducted before wolves were extirpated by the late 1960s from the southwestern United States. We collected carnivore scats (n = 1,682) from the Apache and Gila national forests in Arizona and New Mexico, USA, from April 1998 through October 2001 and identified scats to species using traditional field methods, of which 251 were identified as Mexican wolf scats. We found the diet consisted of large-sized food items (92.8% percent frequency of occurrence [PFO]), primarily elk (Cervus elaphus) adults (36.6% PFO) and calves (36.2% PFO). Biomass calculations indicated that Mexican wolves consumed 414 kg of prey as represented by the scats, with elk representing 76.7% of the biomass. When comparing PFO with percent biomass, PFO calculations may have underrepresented larger food items and percent biomass may have overrepresented smaller food items. We compared the diet composition of Mexican wolf scats (n = 251) to the diets reported in previous North American gray wolf (C. lupus) studies (n = 7). The high proportion of elk in Mexican wolf diets in our study area may reflect the low-density, early colonizing stage of the wolf population and elk probably being the most numerous ungulate in our study area. Our results suggested that free-ranging Mexican wolves consumed a higher proportion of large-sized prey than other North American gray wolves. Our results provide baseline diet information for a newly reestablished wolf population.

Scat removal: a source of bias in feces-related studies

Abstract Consumption of feces (coprophagy) may alter findings of dietary studies and population estimates based on fecal analyses, but its magnitude is poorly understood. We investigated seasonal incidence of scat removal on Fort Riley, Kansas, from January through December 2000. We placed feces from captive bobcats (Lynx rufus), captive coyotes (Canis latrans), and free-ranging coyotes randomly on tracking stations in forest and prairie landscapes to determine rates of scat removal by local wildlife. Rates of removal of feces from captive bobcats, captive coyotes, and free-ranging coyotes varied from 7% during spring to 50% during summer. We identified opossums (Didelphis virginiana) as the most common species present at stations where scat removal occurred. Feces may be an important seasonal source of food for opossums and may provide seasonal dietary supplements for other species. Other factors responsible for disturbance of feces included a woodrat (Neotoma floridana) caching coyote feces, removal of captive coyote feces by free-ranging coyotes accompanied by deposition of fresh feces, a bobcat burying a captive bobcat sample and depositing fresh feces, and rain storms. Dietary studies based on fecal analyses could be biased by scat removal, assuming that contents in feces are representative of the proportion of foods consumed.

Survival and cause-specific mortality among furbearers in a protected area

Abstract Information is needed on protected furbearer communities to help understand the ecological impacts of trapping pressure on furbearer populations. We monitored coyotes (Canis latrans), bobcats (Lynx rufus), raccoons (Procyon lotor) and opossums (Didelphis virginiana) from October 1995 to March 2000 in northeastern Kansas to determine survival and cause-specific mortality of a furbearer community protected from trapping. Annual survival did not differ among years or between sexes for all species, but seasonal differences occurred for coyotes, raccoons and opossums. For coyotes, deaths from humans resulted in decreased survival in winter compared to summer. For raccoons and opossums, deaths from coyote predation resulted in decreased survival in winter compared to summer. Annual survival rates of coyotes (0.71), bobcats (0.77) and raccoons (0.71) were similar to those reported from lightly exploited populations. Annual survival of opossums (0.06) appeared to be extremely low although survival of opossums was not reported in previous studies. The wide-ranging movements of coyotes and bobcats took them off the protected area and made them susceptible to anthropogenic mortalities (80% and 83% of deaths, respectively). In contrast, coyote predation accounted for 40% and 76% of raccoon and opossum deaths, respectively. The high density of coyotes (0.8–0.9 coyotes km2) on the protected area likely contributed to the high predation rates on raccoons and opossums.

Persistence of carnivore scat in the Sonoran Desert

Abstract Estimates of population density and diets of predators are often based on detection and examination of feces (scats). Decomposition rates and manipulation or consumption of scats by animals could bias studies that use scat to investigate life-history parameters. We investigated the longevity (persistence), nutritional content, and fates of coyote (Canis latrans) and bobcat (Lynx rufus) scats near Tucson, Arizona from April 2000–July 2001. We established 42 stations containing scats along roads in the Sonoran Desert. We placed half of the scats in protective cages to estimate degradation rates apart from disturbance by other animals. Unprotected scats disappeared sooner than expected based on decomposition rate. When pooled over spring, summer, autumn, and winter, median survival of unprotected wild canid scats was 11 days, but decreased to 4 days in June–July 2001. Some scats were moved to white-throated woodrat (Neotoma albigula) dens. A 1-m increase in distance of scats to woodrat dens resulted in a 2.2% (Wald 95% CI: 0.9–3.4%) increase in persistence (days) of unprotected scats of all types over all seasons. In June and July 2001 a 1-m increase in distance of scats to woodrat dens resulted in a 4% (Wald 95% CI: 2.7–5.4%) increase in persistence (days) of unprotected scats of wild canids. Studies based on detection, counts, or collection of predator scats may be biased by scat persistence. Investigators can minimize bias through frequent sampling and by accounting for local scat-degradation rates.

Coyote Family Spatial Relationships with Reference to Poultry Losses

Spacing of 19 coyotes (Canis latrans), representing 8 families, and their proximity to 2 turkey production sites (TPS) were studied during summer and fall 1976 and 1977 near Waverly, Nebraska. Sixteen of the 19 coyotes were radio-tagged and toe-clipped; 3 were ear-tagged and toe-clipped. Related pups remained closer together (average distance apart during day = 0.42 km, during night = 0.37 km) than related adults and pups (average distance apart during day = 1.15 km, during night = 1.59 km), or mated adults (average distance apart during day = 1.63 km, during night = 1.85 km). Family groups occupied nonoverlapping, contiguous home ranges. Three of 9 coyotes tracked during 1976 and 5 of 13 coyotes tracked in 1977 survived and remained on the area until the next denning season. Mortality due to hunting and trapping during the winter was 9 of 11 coyotes. Although 8 families ranged within 5 km of the TPS, only 3 tagged coyotes from 2 different families were responsible for losses. Pups were not responsible for increased turkey losses observed during late summer and fall. J. WILDL. MANAGE. 45(3):641-649 Understanding coyote spatial relationships requires consideration of their social structure and hunting behavior. The social unit among coyotes is the family, and revolves primarily around a reproductive female (Gier 1975). Coyotes are considered efficient, solitary hunters of small prey, but are known to hunt in pairs or as a family unit (Young and Jackson 1951, Dobie 1961, Ryden 1975, Camenzind 1978). Little is known about the postdenning relationships of adult coyotes and their pups, especially among coyotes damaging poultry and livestock. Ryden (1975), Hallett (1977), and Camenzind (1978) presented limited observations of family interactions and movements during the pup-rearing period. Andelt and Gipson (1979) reported on domestic turkey losses to radio-collared coyotes, but did not determine the impact on turkeys of pups of adults known to cause turkey losses. Our objectives were to identify (1) coyote intraand interfamily spatial relationships during the postdenning period and (2) the relationships of movements of damaging adult coyotes and their pups to turkey losses at turkey production sites. We are indebted to L. I. Bevans, R. M. Bevans, B. L. Bevans, W. B. Bevans, and E. V. Sheary of the Bevans Turkey Farm for supplying information regarding poultry losses; D. A. Baker, J. G. Bruner, E. S. Jochum, S. A. Kilpatrick, D. G. Luce, and B. R. Mahan for field assistance; R. K. Allen and W. G. Sheehan for pilot services; J. M. Inguanzo and K. C. Nelson for computer consulting; W. F. Andelt, R. M. Case, H. T. Gier, H. L. Gunderson, and W. M. Tzilkowski for manuscript review; and J. L. Andelt for typing earlier drafts of the manuscript.