Pup-rearing Period Research Articles

Pup rearing: The role of mothers and allomothers in free-ranging domestic dogs

Allomaternal care (AMC) is provided to the offspring by individuals other than the genetic mother, including several seemingly altruistic behaviors such as babysitting, carrying, nursing, crèching, or huddling for thermoregulation. To determine whether there is any allomaternal care among free-ranging domestic dogs, from March 2015 to May 2019 a total of eight dog groups consisting of 19 adult females (range 2–3 females per group) that were matrilineal relatives, i.e., maternal grandmothers, aunts, daughters, sisters were observed during pup-rearing period (1st to 13 weeks of pups’ life). During the first two weeks, lactating bitches were observed to spend the most time with their own pups and suckled for almost the entire observation period (30 min). Lactating mothers started to venture out of their dens for short foraging trips when the pups were 1 week old, but it was more frequent at 3 weeks of age. From the 3rd week of kin-related pups’ life the lactating mothers were observed to wean, with a parallel shift of nursing and regurgitation for the pups done by other kin-related females showing the evidence of allonursing. The occurrence of all types of nursing activities i.e., duration of contact, nursing, feeding by regurgitation, and protection of pups was higher among the mothers than among the allomothers. In the case of biological mothers, the frequency and duration of contact, nursing and feeding by regurgitation decreased as the puppies aged, meanwhile in the case of allomothers, the frequency and duration of contact, nursing and feeding by regurgitation increased until 6 weeks of age, before switching to a decreasing trend. Allonursing in free-ranging domestic dogs was more common among older bitches i.e., maternal grandmothers. We propose four possible reasons of allonursing in the case of free-ranging dogs- 1) having excess milk perhaps due to high pup mortality allonursing may evolve as low cost behavior in free-ranging dogs, 2) allonursing may provide substantial benefits to pups regarding growth, survival, and the transfer of immune compounds, 3) insufficiency of own mother’s milk may be one of the causes of allonursing, and 4) free-ranging domestic dogs nurse each other’s pups perhaps to promote a set of affiliating and permissive relationships among the group members. As the studied groups contained matrilineal related female dogs that helped each other with allonursing, this study strongly suggests the kin selection theory especially as allonursing is highly prevalent in other, closely related, gregarious wild canids (gray wolves, golden jackals).

Coping with climate change: limited behavioral responses to hot weather in a tropical carnivore

Climate change is widely accepted to be one of the greatest threats to species globally. Identifying the species most at risk is, therefore, a conservation priority. Some species have the capacity to adapt to rising temperatures through changing their phenology, behavior, distribution, or physiology, and, therefore, may be more likely to persist under rising temperatures. Recent findings suggest that the African wild dog Lycaon pictus may be impacted by climate change, since reproductive success is consistently lower when pup-rearing coincides with periods of high ambient temperature. We used GPS collars, combined with generalized linear mixed-effects models, to assess wild dogs’ potential to adapt to high ambient temperatures through flexible timing of hunting behavior. On days with higher maximum temperatures, wild dogs showed lower daytime activity and greater nocturnal activity, although nocturnal activity did not fully balance the decrease in daytime activity, particularly during the denning period. Increases in nocturnal activity were confined mainly to moonlit nights, and were seldom observed when packs were raising pups. Our findings suggest that nocturnal activity helps this cursorial hunter to cope with high daytime temperatures. However, wild dogs appear not to use this coping strategy when they are raising pups, suggesting that their resource needs may not be fulfilled during the pup-rearing period. Given that moonlight availability—which will not change as the climate changes—constrains wild dogs’ nocturnal activity, the species may have insufficient behavioral plasticity to mitigate increasing diurnal temperatures. These findings raise concerns about climate change impacts on this endangered species, and highlight the need for behavior to be considered when assessing species’ vulnerability to climate change.

Hot dogs: High ambient temperatures impact reproductive success in a tropical carnivore.

Climate change imposes an urgent need to recognise and conserve the species likely to be worst affected. However, while ecologists have mostly explored indirect effects of rising ambient temperatures on temperate and polar species, physiologists have predicted direct impacts on tropical species. The African wild dog (Lycaon pictus), a tropical species, exhibits few of the traits typically used to predict climate change vulnerability. Nevertheless, we predicted that wild dog populations might be sensitive to weather conditions, because the species shows strongly seasonal reproduction across most of its geographical range. We explored associations between weather conditions, reproductive costs, and reproductive success, drawing on long-term wild dog monitoring data from sites in Botswana (20°S, 24years), Kenya (0°N, 12years), and Zimbabwe (20°S, 6years). High ambient temperatures were associated with reduced foraging time, especially during the energetically costly pup-rearing period. Across all three sites, packs which reared pups at high ambient temperatures produced fewer recruits than did those rearing pups in cooler weather; at the non-seasonal Kenya site such packs also had longer inter-birth intervals. Over time, rising ambient temperatures at the (longest-monitored) Botswana site coincided with falling wild dog recruitment. Our findings suggest a direct impact of high ambient temperatures on African wild dog demography, indicating that this species, which is already globally endangered, may be highly vulnerable to climate change. This vulnerability would have been missed by simplistic trait-based assessments, highlighting the limitations of such assessments. Seasonal reproduction, which is less common at low latitudes than at higher latitudes, might be a useful indicator of climate change vulnerability among tropical species.

Specialization for aggression in sexually dimorphic skeletal morphology in grey wolves (Canis lupus).

Aggressive behaviour is important in the life history of many animals. In grey wolves (Canis lupus), territory defence through direct competition with conspecifics is severe and often lethal. Thus, performance in aggressive encounters may be under strong selection. Additionally, grey wolves frequently kill large dangerous prey species. Because both sexes actively participate in aggressive activities and prey capture, wolves are expected to exhibit a low level of musculoskeletal sexual dimorphism. However, male wolves more often lead in agonistic encounters with conspecifics and must provision the nursing female during the pup-rearing period of the breeding season. These behaviours may select for males that exhibit a higher degree of morphological adaptation associated with aggression and prey capture performance. To test this prediction, we assessed skeletal sexual dimorphism in three subspecies of grey wolves using functional indices reflecting morphological specialization for aggression. As expected, sexual dimorphism in skeletal shape was limited. However, in two of three subspecies, we found sexually dimorphic traits in the skull, forelimbs and hindlimbs that are consistent with the hypothesis that males are more specialized for aggression. These characters may also be associated with selection for improved prey capture performance by males. Thus, the sexually dimorphic functional traits identified by our analysis may be adaptive in the contexts of both natural and sexual selection. Several of these traits may conflict with locomotor economy, indicating the importance of aggression in the life history of male grey wolves. The presence of functional specialization for aggression in a generally monogamous species indicates that sexual dimorphism in specific musculoskeletal traits may be widespread among mammals.

Intensity of Territorial Marking Predicts Wolf Reproduction: Implications for Wolf Monitoring

BackgroundThe implementation of intensive and complex approaches to monitor large carnivores is resource demanding, restricted to endangered species, small populations, or small distribution ranges. Wolf monitoring over large spatial scales is difficult, but the management of such contentious species requires regular estimations of abundance to guide decision-makers. The integration of wolf marking behaviour with simple sign counts may offer a cost-effective alternative to monitor the status of wolf populations over large spatial scales.Methodology/Principal FindingsWe used a multi-sampling approach, based on the collection of visual and scent wolf marks (faeces and ground scratching) and the assessment of wolf reproduction using howling and observation points, to test whether the intensity of marking behaviour around the pup-rearing period (summer-autumn) could reflect wolf reproduction. Between 1994 and 2007 we collected 1,964 wolf marks in a total of 1,877 km surveyed and we searched for the pups' presence (1,497 howling and 307 observations points) in 42 sampling sites with a regular presence of wolves (120 sampling sites/year). The number of wolf marks was ca. 3 times higher in sites with a confirmed presence of pups (20.3 vs. 7.2 marks). We found a significant relationship between the number of wolf marks (mean and maximum relative abundance index) and the probability of wolf reproduction.Conclusions/SignificanceThis research establishes a real-time relationship between the intensity of wolf marking behaviour and wolf reproduction. We suggest a conservative cutting point of 0.60 for the probability of wolf reproduction to monitor wolves on a regional scale combined with the use of the mean relative abundance index of wolf marks in a given area. We show how the integration of wolf behaviour with simple sampling procedures permit rapid, real-time, and cost-effective assessments of the breeding status of wolf packs with substantial implications to monitor wolves at large spatial scales.

Changes in subantarctic fur seal pups' activity budget and diving behaviours throughout the rearing period

Time spent in the water and diving behaviour of subantarctic fur seals (Arctocephalus tropicalis (Gray, 1872)) at Amsterdam Island in the southern Indian Ocean were investigated using time–depth recorders throughout the pup-rearing period. The main finding of this study, contrary to the findings of previous studies conducted on other fur seal species, was the decrease in the mean daily amount of time spent in the water throughout the pup-rearing period. The decrease in the amount of time spent in the water by older individuals compared with younger ones is likely to be related to the reduction of the pups' energy expenditure with a decreasing provisioning rate by their mothers. No change in the number of dives or the amount of time dedicated to diving relative to the time spent in the water could be detected throughout the pup-rearing period. The mean maximum dive depth increased with pup age and decreased with pup mass, and maximum dive duration was also found to increase with pup age. The positive effect of pup size on dive rates was the only relationship suggesting that pups' growth performance may act positively on the ontogeny of their diving capabilities. The large interindividual variation in the amount of time spent in the water and in dive rates, and the absence of any clear relationship with pup mass and pup growth performance, suggest the existence of alternative strategies: either pups invest more energy in developing their swimming and diving abilities, to the detriment of the body fat stores, or reduce their activity level to enhance body fat stores to increase their postweaning survival rate.

Foraging ecology of subantarctic fur seals Arctocephalus tropicalis breeding on Amsterdam Island: seasonal changes in relation to maternal characteristics and pup growth

The distribution and availability of marine resources are directly affected by seasonal spatial changes in physical and oceanographic features. They are thus likely to influence maternal for- aging provisioning patterns, efficiency, and subsequent pup growth rate of central place foragers such as otariid seals. While previous studies have documented foraging locations and diving activity of female otariids in relation to oceanographic features, few have focused on species characterised by a long pup-rearing period. The present study investigated seasonal changes in foraging parameters in relation to the following oceanographic features and maternal characteristics: foraging grounds (using satellite tags, geolocation, GIS and kernel estimation techniques), at-sea activity budget (using time-depth recorders), and the foraging success and diet of female subantarctic fur seals Arcto- cephalus tropicalis breeding on Amsterdam Island (southern Indian Ocean). The seals mainly ex- ploited the subtropical front, but also exhibited large differences in seasonal distribution, from short trips in restricted foraging areas during summer to widely distributed foraging grounds during the winter. This is consistent with a seasonal shift in diet and an increasing proportion of time being dedi- cated to diving and resting. This increase in foraging trip duration throughout the season paralleled decreasing rates in maternal mass gain and pup growth, suggesting a decrease in food availability. During the summer, maternal mass gain rate and pup growth were related to foraging tactics (percent of time spent diving and in the core foraging area), whereas maternal characteristics such as body length were more important during the latter months of the pup-rearing period. However, no influence of age and thus no apparent advantage of female experience was detected in this study.

Swift fox (Vulpes velox) home-range dispersion patterns in southeastern Wyoming

We monitored dispersion patterns of swift foxes (Vulpes velox) for 3 years in shrub-grassland habitats on the margin of the species' geographic range near Medicine Bow, Wyoming. Annual home-range size was 18.6 ± 1.6 km2 (mean ± SE, n = 13) and was similar to home-range estimates reported in other studies conducted within grassland habitats in other portions of the species' geographic range. Male home ranges were larger than those of their mates during pup-rearing periods (P < 0.04) but were similar in size during the dispersal period. The home ranges of both sexes were smallest during the pup-rearing period. The degree of home-range overlap for mates (biological periods combined) was high (range = 27.4–100%, mean ± SE = 70.8 ± 0.03%, n = 26 pairs) but was minimal between adjacent pairs (range = 0.2–36%, mean ± SE = 11.9 ± 2.4%, n = 10 pairs), suggesting territorial behavior. Occupied home ranges were distributed similarly each year despite one or both pair members often being new. Swift fox home-range size varied seasonally, and home-range dispersion patterns appeared to be influenced by the presence of other fox pairs and the recent use of an area by other swift foxes.

Milking strategy in subantarctic fur seals Arctocephalus tropicalis breeding on Amsterdam Island: evidence from changes in milk composition.

Milk composition was investigated throughout the 10-mo pup-rearing period in subantarctic fur seals (Arctocephalus tropicalis) breeding on Amsterdam Island. The mean milk composition was 42.8% +/- 5.7% lipid, 12.1% +/- 1.5% protein, and 42.6% +/- 7.3% water. Subantarctic fur seals breeding on Amsterdam Island produced one of the richest milks ever reported in otariids (20.4 +/- 2.9 kJ/g), with lipid content contributing 85% of total gross energy. The high lipid levels measured in the milk of subantarctic fur seals breeding on Amsterdam Island is consistent (i) with the relatively long time lactating females spend at sea, due to the relatively poor local trophic conditions near the colony that necessitate that they travel long distances to reach the foraging grounds, and (ii) with the consequently short time mothers spend with their pups ashore. Milk composition changed according to the time mothers were fasting ashore: milk produced during the first 2 d spent ashore, when more than 80% of milk transfer occurred, had higher levels of lipids, proteins, and gross energy than milk produced later during the visit ashore, suggesting that the pups were fed with two types of milk during a suckling period. Throughout the year, mothers in good condition produced milk of higher lipid content than others, suggesting that individual foraging skills contribute to enhance milk quality. Milk lipid and gross energy content varied with pup age, according to quadratic relationships, increasing during the earlier stages of lactation before reaching asymptotic values when pups were 180 d old. The stage of lactation appears to be a better predictor of milk lipid content than the duration of the preceding foraging trip, suggesting that either changes in the nutritional requirements of the pup and/or seasonal changes in trophic conditions act on milk composition. These changes in milk quality may also be related to changes in maternal care; lactating subantarctic fur seals apparently reallocate their body reserves toward gestation rather than lactation at the end of the pup-rearing period.

MATERNAL CARE IN THE SUBANTARCTIC FUR SEALS ON AMSTERDAM ISLAND

This paper reports the first study of maternal input and care from birth to weaning in a fur seal with a long pup-rearing period: the subantarctic fur seal Arctocephalus tropicalis breeding on the temperate Amsterdam Island, Indian Ocean. The protracted weaning period provided the opportunity for examination of maternal care in relation to seasonal changes in the requirements of the mother–pup pair and environmental conditions. During the reproductive season 1995–1996, maternal care was investigated in terms of provisioning (maternal attendance) pattern while diving effort was investigated using time depth recorders in summer and winter. Maternal input was calculated in terms of the absolute rate of pup mass gain and, ultimately, pup growth rate and pup body mass at weaning. Lactating subantarctic fur seals perform one of the longest attendance cycles described in fur seals, spending on average 11–23 d at sea from summer to winter. The time mothers spend ashore suckling their pup is also long (∼4 d) but remains constant throughout the year. Throughout the year, maternal input should be described as follows: mothers spending a long time at sea store a large amount of body reserves that provide them a good body condition. Consequently, they spend a long time ashore to transfer their body reserves to their pups. However, mothers spending short attendance periods increase the mass transfer efficiency, probably by decreasing their metabolic overhead. In summer, maternal care was mostly controlled by pup traits: maternal absences appeared to be controlled by pup fasting ability, while maternal input was controlled by pup ingestion ability, i.e., pup body size and the time the pup was suckling. In fall, pups were no longer limited in milk ingestion, and maternal input was mostly controlled by maternal traits (e.g., body length and experience). In winter, maternal input decreased as the pup became older despite an increase in maternal diving effort. We propose that, in winter, maternal requirements increase, probably in response to increasing costs of gestation and because of a decrease in food resource availability. Pups whose mother performed short and regular foraging trips grew faster and were heavier at weaning than other pups. This is discussed in term of pup fasting endurance and maternal experience. Finally, we found a window of foraging trip durations that maximizes the net rate of energy acquisition of the pup, suggesting that in subantarctic fur seals there may not exist one optimal maternal attendance pattern, but a range of patterns promoting the same maternal fitness.

The diet of Antarctic fur sealsArctocephalus gazella during the breeding season at South Georgia

The diet of lactating female Antarctic fur sealsArctocephalus gazella at South Georgia was investigated during the pup-rearing period (January/March) of 1991–1994. Antarctic krillEuphausia superba was the main prey item, occurring in 88% of all scats (n=497), whereas fish occurred in 47% and squid in 5% of all scats. There was considerable intra- and inter-annual variation in the characteristics of krill taken by fur seals. The distribution of krill sizes taken suggests that fur seals are not actively selecting particular sizes of krill and, therefore, that the krill in the diet reflects the krill available around South Georgia. The absence of group 3 krill (44–48 mm in length) in the South Georgia area, as indicated by their absence in the diet of seals, is suggested as a possible reason for low availability of krill and the subsequent reproductive failure among krill predators. The frequency of occurrence of fish was much higher than in previous studies; the pattern of fish consumption showed a consistent seasonal pattern in 3 of the 4 years studied. Of the total number of the myctophidProtomyctophum choriodon, the most numerous fish taxon, 98% were taken between early February and the middle of March.Champsocephalus gunnari andLepidonotothen larseni agg., which both feed on krill, dominated the fish component of the diet outside this period and together constituted 94% of the total estimated biomass of fish consumed. The intra- and inter-annual variability in the diet of Antarctic fur seals emphasise the need for diet studies to be conducted during the entire pup-rearing periods of several years.

Population Demography of Antarctic Fur Seals: The Costs of Reproduction and Implications for Life-Histories

1. This study examined the costs of reproduction in terms of future survival and reproduction in female Antarctic fur seals from Bird Island, South Georgia. It used mark-recapture data from 11 consecutive years, including 3 years when several indices showed that food availability was well below average. 2. Population age structures were used, in conjunction with the measured age-specific survival rates, to estimate the rate of increase of the population as 10.7% per annum. 3. The average annual survival rate was 0.83 (SD = 0.10) with a range from 0.65 to 0.93. Survival rate showed no trend through time but was weakly correlated with pup growth rate, suggesting that it may be influenced by availability of food. Survival rate was unrelated to any other environmental or demographic parameter including population size. 4. There was no evidence of senescence. Survival rate was not related to year of birth or age, after accounting for variation due to pregnancy and calendar year. Survival was reduced as a result of pregnancy which accounted for 40-50% of adult female mortality. This effect was greatest in the age classes with the highest reproductive output (ages 5-8 years). 5. Mean pregnancy rate was 0.70 (SD = 0.11) with an interannual range of 0.59-0.88. Although females normally produced their first pups at age 3-4 years, pregnancy rate peaked at age 8 years and declined thereafter. Otherwise pregnancy rate was unrelated to the environmental or demographic variables we tested. Food availability during the pup-rearing period had no effect on pregnancy rate. 40-50% of failures to become pregnant related to animals having been pregnant in the previous year. 6. Reproduction incurs costs to females, in terms of reduced survival and future fecundity, and consequently, on average, females which survive longest tend to do so because they have lower fecundity.

Home Range and Habitat Use of Coyotes in a Farm Region of Vermont

We studied home ranges, activities, and habitat use of 29 radio-collared coyotes (Canis latrans) representing 11 different social groups in the Champlain Valley of Vermont. Between July 1984 and December 1986, 1,870 radio locations were obtained. Home ranges averaged 18.7 ? 4.6 (SE) km2 and 17.1 ? 3.2 km2 for adult males and females, respectively. All members of individual family groups shared the same home range. Home ranges were smaller during the pup-rearing period (15 Apr-15 Jul) than at other times of the year. Home ranges of adjacent social groups showed limited overlap, but smaller core activity areas were mutually exclusive. Study animals preferred hardwood forests during winter and spring, and farmland during summer and fall. J. WILDL. MANAGE. 55(3):433-441 In the last 50 years, coyotes have expanded their range east into northern New England, Quebec, and the maritime provinces of Canada (Richens and Hugie 1974). The first sightings of coyotes in Vermont were recorded in the 1940's (Pringle 1960), and they are now common throughout the state. The rapid increase in the coyote population in the Northeast is of ecological and management interest because of the impact these animals may have on livestock, indigenous prey species, and competing predators (Todd 1985, Litvaitis and Harrison 1989). Previous studies of coyotes in the Northeast have been conducted primarily in heavily forested habitats (Messier and Barrette 1982, Harrison and Gilbert 1985, Major and Sherburne 1987). No comprehensive eastern coyote research has been reported from a farming region, This content downloaded on Wed, 12 Dec 2012 22:50:46 PM All use subject to JSTOR Terms and Conditions 434 COYOTES IN VERMONT * Person and Hirth J. Wildl. Manage. 55(3):1991 although most farming is livestock-oriented and has high potential for conflict with coyotes. Furthermore, little information exists concerning coyote ecology in semi-rural residential areas where potential for human conflict with coyotes is also high. The objectives of our study were to examine home ranges and habitat use of coyotes in an agricultural region of Vermont and to compare these results with studies of eastern coyotes in forested environments. Because portions of our study area included habitat in transition from rural to urban, we examined coyote activities in these areas as well. This descriptive study is intended to provide baseline information prior to hypothesis-testing research on the interaction of coyotes and white-tailed deer (Odocoileus virginianus) in both agricultural and forested habitat. Our research was funded by Vermont Department of Fish and Wildlife through Federal Aid in Wildlife Restoration Project W-45-R-5. We are grateful to B. W. Day, Jr. and J. J. DiStefano of that agency for their support and encouragement throughout our work. Woodstream Corporation donated Softcatch? traps. D. E. Capen and G. J. Badger provided valuable advice on data analysis. S. J. Williamson, E. B. Soper, K. G. Timothy, and especially R. Hoffman and M. A. Ingle assisted in trapping and radiotracking. We are grateful to D. E. Capen, S. DeStefano, J. J. DiStefano, D. J. Harrison, M. A. Ingle, and A. W. Todd for reviewing earlier versions of this manuscript. Finally, we thank the many farmers who gave us permission to trap on their land.

Snake-directed mobbing by the Formosan squirrel Callosciurus erythraeus thaiwanensis

The Formosan squirrel Callosciurus erythraeus thaiwanensis was often observed mobbing the snake Elaphe climacophora. A total of 36 natural and 21 experimentally induced mobbings were observed and analyzed. The number of attending squirrels per mobbing event varied from one to seven, and 84% of observed mobbings were performed by more than one individual. The duration of a mobbing bout increased directly with the number of assembled mobbers. In 68% of cases, one adult female was one of the mobbers; there was never more than one female per mob. The number of assembled males per mob varied from 0 to 5; 40% of the mobbings involved two or more males. This difference is correlated to a difference in spacing patterns of both sexes; female home ranges were distributed exclusively, whereas male home ranges overlapped each other. Females mated with multiple males whose home ranges overlapped theirs. Female's reproductive status (conception, lactation, and weaning) affected their intensity of response to the playback of mobbing calls, females in pup-rearing period being the most sensitive. One function of the mobbing appears to be defense of the young against snake predation. Females mobbed more intensively and longer than males. Males that had resided at the study site for at least 1 year tended to mob more frequently than intruders.

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.

Red Fox Prey Demands and Implications to Prairie Duck Production

Experiments were conducted during spring and summer with 33 red foxes (Vulpes vulpes) to determine prey demands, feeding characteristics, and growth rates using natural foods. Pups began eating prey the 4th week after birth. Then, prey consumption averaged 1.38 and 1.90 kg/pup/week for weeks 58 and 9-12 of the denning season respectively, and 2.54 kg/pup/week for the postdenning period. Feeding by adults averaged 2.25 kg/adult/week. Free water was not needed by either pups or adults. About 90 percent of the prey offered to pups on simulated natural diets was consumed; remains varied with prey availability and prey type. Prey biomass required by a typical fox family was estimated at 18.5 kg/km2 for the 12-week denning season and 2.4 kg/km2/week for the postdenning period. Because of the large prey demands, ducks could represent a small part of the foxes' diet and yet be of consequence to the productivity of particular species. An example is provided for the mallard (Anas platyrhynchos). J. WILDL. MANAGE. 42(3):520-527 Many studies (e.g., Errington 1935, Scott 1943) show that red foxes are largely carnivorous, but few studies document the quantities of natural prey required. Knowledge of prey requirements is useful for assessing fox impact on prey populations. During summer and winter individual red foxes eat 0.38-0.57 kg of prey per day (Scott 1943, Lockie 1959, Vogtsberger 1972, Ryszkowski et al. 1973). Red foxes have high prey assimilation rates with 85-97 percent being digestible depending on food type (Vogtsberger and Barrett 1973, Litvaitis and Mautz 1976); 87 percent of the ingested energy is used for body maintenance (Vogtsberger and Barrett 1973). Red foxes are not noted for gorging or for carrying heavy fat loads; thus, survival seems to depend on regular feeding. Behavioral traits such as caching (Murie 1936, Macdonald 1976) insure the availability of food during periods of prey scarcity. The purpose of this paper is to provide quantitative estimates of prey demands (including nonconsumed prey parts) of adult and pup red foxes during the spring and summer pup-rearing period, and to relate these demands to predation on prairie nesting ducks during the nesting period. Emphasis is on the approximate 12-week red fox denning season which in the northern prairie region begins in early April and coincides with the duck nesting season (Sargeant 1972). This period is of particular consequence because adult foxes are caring for pups and because predation then can affect duck production in local areas. I appreciate the assistance of S. H. Allen and R. T. Eberhardt in capturing the foxes, of numerous individuals from the Northern Prairie Wildlife Research Center and the North Dakota Game and Fish Department in providing prey, of L. E. Eberhardt and T. J. Dwyer in conducting feeding tests, and of G. L. Pearson for diagnostic services. D. H. Johnson provided statistical advice and together with G. L. Krapu and R. J. Greenwood critically reviewed the manuscript; drafting was by C. W. Shaiffer. G. L. Krapu and C. W. Dane provided unpublished data on duck weights in spring.