Showing papers in "Journal of Wildlife Management in 1989"

Survival analysis in telemetry studies: the staggered entry design

Abstract: The estimation of survival distributions for radio-tagged animals is important to wildlife ecologists. Allowance must be made for animals being lost (or censored) due to radio failure, radio loss, or emigration of the animal from the study area. The Kaplan-Meier procedure (Kaplan and Meier 1958), widely used in medical studies subject to censoring, can be applied to this problem. We developed a simple modification of the Kaplan-Meier procedure that allows for new animals to be added after the study has begun. We present 2 examples using telemetry data collected from northern bobwhite quail (Colinus virginianus) to show the simplicity and utility of the Kaplan-Meier procedure and its modifications. The log rank test used to compare 2 survival distributions can also be modified to allow for additions during the study. Simple computer programs that can be run on a personal computer are available from the authors. J. WILDL. MANAGE. 53(1):7-15 Radio-tagged animals are used to study survival. Present techniques for analyzing data from these studies assume that each survival event (typically an animal surviving a day) is independent and has a constant probability over all animals and all periods (Trent and Rongstad 1974, Bart and Robson 1982, Heisey and Fuller 1985). We believe these assumptions are often unrealistic and restrictive. White (1983) generalized discrete approaches using the same framework as that of band return models (Brownie et al. 1985) and he developed a flexible computer program (SURVIV) for use with his approach. Heisey and Fuller (1985) generalized the Trent and Rongstad (1974) approach to allow mortality from different causes (e.g., predation, starvation) and developed a microcomputer program called MICROMORT. Typically an animal's exact survival time (at least to within 1-2 days) is known unless that survival time is right censored (i.e., only known to be greater than some value). Pollock (1984) and Pollock et al. (1989) suggested a useful approach based on continuous survival models allowing right censoring that is widely used in medicine and engineering (Kalbfleisch and Prentice 1980, Cox and Oakes 1984) and provided examples of the Kaplan-Meier procedure. The Kaplan-Meier procedure does not require specification of a particular parametric continuous distribution; e.g., the exponential or Weibull. Related ecological papers using survival methods include Muenchow (1986), Pyke and Thompson (1986), Kurzejeski et al. (1987), and White et al. (1987). We present a simple description of the Kaplan-Meier procedure with an example using northern bobwhite quail survival data collected by PDC. We then generalize the Kaplan-Meier procedure to allow gradual (or staggered) entry of animals into the study. The calculations are illustrated with an example from the quail data. Finally, we present the log-rank test for comparison of survival distributions (modified for staggered entry of animals) with an example. We also present a discussion of model assumptions and directions for future research. We thank J. D. Nichols and W. L. Link for helpful comments on an earlier draft of this paper. We acknowledge G. C. White and D. M. Heisey for their helpful reviews that improved the final version. THE KAPLAN-MEIER OR PRODUCT LIMIT PROCEDURE The Kaplan-Meier or product limit estimator was developed by Kaplan and Meier (1958) and is d scussed by Cox and Oakes (1984:48) and Kalbfleisch and Prentice (1980:13). The survival function (S[t]) is the probability of an arbitrary animal in a population surviving t units of time from the beginning of the study. A nonparametric estimator of the survival function can be obtained by restricting ourselves to the discrete time points when deaths occur a1, a2, ..., ag. We define r, . . . , rg to be the numbers of an-

Generalized procedures for testing hypotheses about survival or recovery rates

Abstract: Comparisons of survival or recovery rates from different time periods or geographic regions may be difficult to accomplish using the Z-tests suggested by Brownie et al (1985) We propose a general Chisquare statistic that addresses an unambiguous null hypothesis of homogeneity among several survival or recovery rates With this statistic, specific hypotheses of differences in rates can be simultaneously tested using contrasts If necessary, a posteriori multiple comparisons can also be conducted that incorporate an adjustment for Type I error J WILDL MANAGE 53(1):137-142 Recent advances in analytical techniques (Seber 1965, Brownie et al 1985) have enabled biologists to estimate survival and recovery rates and the standard errors of these estimates for animal populations As band-recovery (or markrecapture) data accumulate for many populations, increasing interest has focused on temporal and geographic variation in survival and recovery rates We briefly review methods of testing hypotheses about homogeneity in these rates, and describe a Chi-square test that can be of general use in their analyses This statistical method supplements a full banding analysis, and can be of value when the hypotheses of interest cannot be tested using the models available, when survival or recovery rate estimates (and associat d variances and covariances) are already av ilable from previous analyses, or when the band recovery analysis procedures are unavailable or inconvenient to use We discuss applications to multiple comparisons of survival rates derived from band-recovery models (Brownie et al 1985) However, the methods are applicable to any rate estimates that have associated variances and covariances We thank R E Trost for suggesting that we prepare this manuscript J D Nichols, G W Pendleton, E A Rexstad, R L Kasul, and R E Trost critically reviewed the manuscript METHODS OF COMPARING SURVIVAL RATE ESTIMATES Several methods have been proposed as statistical tests for homogeneity of survival or recovery rates These methods can be divided into those using original data, and those using rate estimates derived from data, with associated I Present address: US Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, MD 20708 This content downloaded from 2074613101 on Sat, 08 Oct 2016 05:29:35 UTC All use subject to http://aboutjstororg/terms 138 SURVIVAL RATE COMPARISONS * Sauer and Williams J Wildl Manage 53(1):1989 variances and covariances Methods using banding and recovery data have been described by Brownie et al (1985), who developed a series of band recovery models that incorporate different assumptions about timeand age-specificity of survival and recovery rates These models have been generalized to include a greater variety of patterns of variation in recovery and survival rates by White (1983) and Conroy and Williams (1984) As part of the model selection procedure, these authors provided likelihood-ratio tests to determine which model best fits the data However, their procedures were limited in the nature of the hypotheses that are testable Once the proper band-recovery model from Brownie et al (1985) is selected, it often is useful to examine differences in survival rates for subsets of the time periods used in the original data For example, Rogers et al (1979) assessed the effect of hunting regulations on mallard (Anas platyrhynchos) populations by identifying years in which regulations were liberal or restrictive Using survival rate estimates from Brownie et al (1985), Rogers et al (1979) tested for differences between mean survival rates in the 2 sets of years In some instances it is practical to test such hypotheses by incorporating them directly in the band recovery procedures (White 1983, Conroy and Williams 1984) However, if the original data are not available, if the data fail to meet the requirements of the procedures (due to small sample sizes that require the merging of many cells), or if the hypotheses themselves are nonstandard (eg, comparisons are desired for survival rates across several populations), then another approach is necessary The use of analysis of variance (ANOVA) (Anderson 1975) is an inefficient alternative, because the variances of the survival or recovery rates are ignored An alternative method circumventing these problems would be of great value Brownie et al (1985:180-182) suggested a Z-statistic as a general method of comparing groups of survival rates As Brownie et al (1985) point out, this is actually a test of the null hypothesis that some contrast of the survival rates (s) is equal to zero, or: Ho: cs, + c2s, + + CNSN = 0, (1) where each c is a constant with the constraint

Factors affecting black bear reproductive success and cub survival

Abstract: Evaluation des relations entre la qualite nutritionnelle du regime alimentaire des femelles,leur condition physique,le succes reproducteur et la survie des oursons apres la naissance

Impaired reproduction of mallards fed an organic form of selenium

Abstract: We fed mallards (Anas platyrhynchos) diets supplemented with 0-, 1-, 2-, 4-, 8-, or 16-ppm selenium in the form of selenomethionine. We fed another group of mallards a diet containing 16-ppm selenium as selenocystine. Females fed the control diet produced a mean of 8.1 ducklings that survived to 6 days of age, which was significantly greater than the 4.6 young produced by females fed 8-ppm selenium as selenomethionine and the zero surviving young of females fed 16-ppm selenium as selenomethionine. Selenocystine did not impair reproduction. Diets containing 8and 16-ppm selenium as selenomethionine caused malformations in 6.8 and 67.9%, respectively, of unhatched eggs compared with 0.6% for controls. The most common malformations were of eyes, bill, legs, and feet. Selenium did not affect the onset or frequency of egg laying, egg size, shell thickness, fertility of eggs, or sex ratio of ducklings. Reduced survival and growth occurred in ducklings hatched from groups whose parents had received 8or 16-ppm selenium as selenomethionine, even though all ducklings were fed a control diet. Concentrations of selenium in eggs and liver of adults could be predicted from dietary concentrations. We conclude that the dietary threshold of selenium as selenomethionine necessary to impair reproduction is between 4 and 8 ppm. It is difficult to identify 1 level of selenium in eggs that will be diagnostic of reproductive impairment in the field because different chemical forms of selenium appear to have different toxicities in eggs. However, when eggs from a wild population contain > 1-ppm selenium on a wet-weight basis, reproductive impairment may be possible and should be evaluated in that population. At 5-ppm selenium in eggs, reproductive impairment is much more likely to occur. J. WILDL. MANAGE. 53(2):418-428 Selenium is a trace element in the earth's crust and, in small amounts, is essential to good health in animals. Too much selenium, however, is toxic to animals. Reproductive failure of chickens caused by selenium poisoning was noted in South Dakota as early as the 1930's (Poley and Moxon 1938). Grains grown on seleniferous soils proved to be the source of the toxic concentrations of

Effects of Habitat Characteristics on Gadwall Nest Predation and Nest-Site Selection

Abstract: We compared characteristics of successful gadwall (Anas strepera) nests and those destroyed by mammalian predators (i.e., striped skunks [Mephitis mephitis]). Lateral cover density, understory cover height, species richness, vegetative penetrability, and patch size were significant determinants of the fate of a nest. Nest success was also influenced by 3 nonvegetative variables: minimum distance to water, dike width, and nest initiation date. Predation rates on nests differed (P 1.0 m), dense biennial and perennial weeds such as thistle (Cirsium arvense), stinging nettle (Urtica dioica), and teasel (Dipsacus spp.), and lacked well-developed understory (ground vegetation). The proportional occurrences of habitats A, B, and C were 33, 42, and 25%, respectively. Beginning in late May, we located nests by flushing females with a slow moving truck and occasional bursts of the truck's horn. This procedure was effective because all nests occurred within 10 m of the dike road. Density of waterfowl nests on the study area was determined by a complete enumeration verified by intensive ground searches in each area. Data recorded for each nest included species, number of eggs, stage of development (Weller 1956), and habitat. Pin flags were placed perpendicular to each nest at the edge of the road. One hundred seventy artificial nests were placed at random distances perpendicular to the dike road at regular intervals along the dike. They consisted of 2 chicken eggs the size of gadwall eggs placed in a shallow, excavated bowl. The same procedures employed for natural nests were used for artificial nests. Because predation rates for natural nests This content downloaded from 157.55.39.186 on Tue, 12 Apr 2016 09:03:55 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 53(1):1989 HABITAT NEST PREDATION * Crabtree et al. 131

Winter survival of female American black ducks on the Atlantic coast

Abstract: We used radio telemetry to monitor the winter survival and cause-specific mortality of 227 female American black ducks (Anas rubripes) captured in New Jersey and Virginia, 1983-85. Mean survival rate for 19 December-15 February was 0.65. Survival from hunting and nonhunting risk was 0.84 and 0.78, respectively. Causes of nonhunting mortality included predation and emaciation (winter stress). After-hatchyear (AHY) ducks had a higher probability of survival than hatch-year (HY) ducks (0.73 vs. 0.60); most of this difference was related to survival from nonhunting risk. After-hatch-year ducks with body masses > median had a higher survival probability (0.85) than AHY ducks with < median body masses (0.61) because of differential survival from hunting risk. Hatch-year ducks had lower body mass than AHY ducks, but among HY ducks body mass was not related to survival. There were no consistent patterns in survivorship in relation to mean daily temperature, although the timing of the onset of low temperatures and storms may have influenced movement patterns. Our estimated survival rates are consistent with estimates from other studies of seasonal and annual survival. It may be possible to manage habitats for population segments at high risk (HY and low body mass birds), and increase black duck survivorship. J. WILDL. MANAGE. 53(1):99-109 Populations of American black ducks have declined from the 1950's to present (Barske 1968, Grandy 1983, Feierabend 1984). Reasons for the decline are unknown but may be related to specific causes of mortality such as hunting (Blandin 1982, Krementz et al. 1988), predation (Ringelman and Longcore 1983), competition from and hybridization with mallards (Anas platyrhynchos) (Johnsgard 1961, 1967), and habitat losses (Barske 1968). Winter is a critical time for black ducks, because of high energetic demands (Albright 1981, Reinecke et al. 1982). Reinecke et al. (1982) demonstrated that immature females achieved adult structural size, but were lighter in weight and had smaller nutrient reserves than did adults during their first winter. Other studies have corroborated a link between age, body condition, and probability of survival. Hepp et al. (1986) reported that the probability of being shot by hunters for mallards in poor condition was higher than for those in better condition. Haramis et al. (1986) reported a direct relationship between the body mass of canvasbacks (Aythya valisineria) in early winter and probability of surviving the winter. Although immature black ducks are more vulnerable to hunting (Schierbaum and Foley 1957, Krementz et al. 1988), and have lower annual survival rates than do adults (Blandin 1982, Krementz et al. 1987), whether age-specific mortality persists through winter, or occurs primarily during the postfledging period and early hunting season is unknown. Managers need estimates of winter survival rates and identification of mortality sources to understand black duck population dynamics and assist in the management of black duck populations. Our objectives were to estimate survival rates of black ducks during winter, examine specific components of mortality, specifically hunting versus nonhunting mortality, and examine variation in survival rates during winter in relation to age, body condition, time, geographic location, and weather conditions. We appreciate the assistance of E. L. Derleth, N. Dietz, B. Dirks, B. L. Estel, S. Holzman, A. G. Larochelle, J. M. Morton, H. H. Obrecht III, S. R. Perin, N. Phelps, H. G. Russell, M. A. Spoden, J. M. Walsh, and G. Wright in the collection of field data. We also thank F. Ferrigno, New Jersey Fish and Game, G. L. Inman and D. L. Beall of Forsythe National Wildlife Refuge, and D. Holland of Chincoteague National 'Present address: Georgia Cooperative Fish and Wildlife Research Unit, School of Forest Resources, University of Georgia, Athens, GA 30602.

Anthranilate repellency to starlings: chemical correlates and sensory perception

Abstract: We investigated the physicochemical and sensory bases of anthranilate repellency to European starlings (Sturnus vulgaris). Physicochemical parameters that control volatility were positively correlated with avoidance. Nasal trigeminal chemoreception and olfaction were important for sensory detection. Methyl, isobutyl, ethyl, and isobutyl methyl anthranilate are as aversive as dimethyl anthranilate (methyl-N-methyl anthranilate) (DMA). J. WILDL. MANAGE. 53(1):55-64 Bird depredations to agricultural commodities are common and can be economically severe; e.g., livestock feed losses through consumption and spillage (Feare and Wadsworth 1981); disease transmission to livestock (Bickford et al. 1966); and damage to crops, such as sunflowers (Avery and DeHaven 1982), grains (Holler et al. 1982, Bollinger and Caslick 1985, Bullard and York 1985), and fruits (Bollinger et al. 1973, Tobin 1985). Birds also accidentally ingest agricultural chemicals such as carbofuran, fensulfothion, and parathion (Balcomb 1983) as nontarget species; their use of these chemicals may restrict man's use of pesticides in some situations. Efforts to control problem birds include trapping and the use of frightening or lethal chemical agents (Besser et al. 1967, Levingston 1967, West et al. 1967, Feare et al. 1981). These approaches are expensive (Cunningham et al. 1979, Glahn 1981) and fail to create a suboptimal environment for avian feeding activity. Birds often return when control measures are relaxed (Twedt and Glahn 1982). An alternative or supplement to existing control strategies may be the use of flavor chemicals that are selectively repellent to birds. These flavors could be sprayed on crops, or added to livestock feeds or granulated pesticides to prevent or reduce ingestion. One candidate compound is DMA, a human food flavoring that is palatable to livestock (R. Fisher, U.S. Dep. Agric. and J. R. Mason, unpubl. data), but aversive to starlings (Mason et al. 1983, 1985), red-winged blackbirds (Agelaius phoeniceus), Japanese quail (Coturnix japonica), pigeons (Columba livia), jungle fowl (Gallus gallus), herring gulls (Larus argentatus) (Kare and Mason 1985), ring-necked 1 Present address: Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104-3308. This content downloaded from 168.68.1.127 on Sun, 5 Oct 2014 03:05:18 AM All use subject to JSTOR Terms and Conditions 56 ANTHRANILATE R PELLENCY * Mason et al. J. Wildl. Manage. 53(1):1989 Table 1. Available physicochemical parameters of 9 anthranilate derivatives examined as repellents of European starlings in experiments 1 and 2. Experiment and derivative MWa BP No. C % O % N % NAC Experiment 1 Methyl (CsHNO2) 151.2 256 8 21.1 9.3 15.9 Methyl-N-methyl (C,H1,NO2) 165.1 255 9 19.4 8.5 21.8 Ethyl (CgHINO2) 165.2 268 9 19.0 8.5 21.8 Isobutyl (C,,H,5NO2) 193.2 270 11 16.5 7.3 31.1 Isobutyl methyl (C12H17NO2) 207.0 200 12 15.5 6.8 34.8

Winter Resting Site Ecology of Marten in the Central Rocky Mountains

Abstract: We investigated the resting site ecology of American marten (Martes americana) in the central Rocky Mountains during 2 winters, 1985-86 and 1986-87. We found 8 marten used 57 resting sites on 141 occasions. Marten rested primarily in subnivean sites associated with coarse woody debris, including logs and stumps. Use of spruce (Picea spp.)-fir (Abies lasiocarpa) stands by adults was greater than expected and use of lodgepole pine (Pinus contorta) stands was less than expected on the basis of spatial availability. Juveniles used stand types in proportion to spatial availability. Fidelity to individual resting sites and to subnivean sites associated with coarse woody debris was highest among adults. Type of resting site used depended on air temperature at the time of resting; above-snow sites were used during the warmest weather, and subnivean sites associated with coarse woody debris were used during the coldest weather. Marten rested for longer periods where coarse woody debris formed all or part of the resting site than they did at other sites. Log densities were higher and mean log diameters greater in spruce-fir stands than in lodgepole pine stands. Resting sites associated with coarse woody debris occurred primarily in spruce-fir stands, whereas other resting sites occurred in other stand types. Resting sites were closer to streams and lakes than expected. The importance of resting where coarse woody debris is available to provide thermal cover may explain the apparent dependence of marten on old-growth forest in the central Rocky Mountains in winter. J. WILDL. MANAGE. 53(1):191-196 Resting sites used by American marten have been described for a wide range of geographic locations and include a variety of natural and man-made microhabitats (Campbell 1979, Steventon and Major 1982, Martin and Barrett 1983, Buskirk 1984). Locations of resting sites range from the forest canopy to beneath the soil surface. Winter resting sites are often associated with coarse woody debris (CWD), including logs, stumps, and snags (Steventon and Major 1982, Martin and Barrett 1983, Spencer 1987). In summer, marten generally rest in sites above the ground, often in the canopy layer (Masters 1980, Burnett 1981, Martin and Barrett 1983). Temporal differences in resting site preferences could be explained by thermoregulatory needs of marten, or by other factors such as vulnerability to predation. Marten live where above-snow air temperatures (Ta) in winter are lower than their lower critical temperature (T,c = the temp at which an animal must increase its metabolic rate above resting levels to offset thermal losses [16 C]) (Buskirk et al. 1988) by ?50 C. Thus they would appear to pay high energetic costs to rest at or near To in winter. Marten are associated with late successional stands of conifer-dominated forest over a wide geographic area (Francis and Stephenson 1972, Koehler and Hornocker 1977, Simon 1980, Bateman 1986) and have a close and seemingly obligatory association with old-growth stands in the Rocky Mountains in winter (Campbell 1979). However, a clear understanding of why marten are associated with old-growth is lacking. Patte ns of use of resting sites may provide a better understanding of the apparently obligatory nature of this association. We report on characteristics of resting sites used by marten in the Medicine Bow Mountains, Wyoming during 2 winter field seasons. We identify environmental and behavioral correlates of resting site use and draw inferences about the importance of resting site types for thermoregulation. We also discuss the importance of CWD as a resting site component in understanding the old-growth dependency of marten during winter. L. R. Forrest provided invaluable assistance during the winter field studies. We appreciate the cooperation of R. H. Abell, for allowing use of a portion of his trapline for field work. This research was supported by the Committee for Research and Exploration, National Geographic Society, the U.S. Forest Service (USFS), Rocky Mountain Forest and Range Experiment Station, and the Office of Research, University of Wyoming. We thank the Wyoming Game and

Relationships of Population Size and Recruitment of Pintails to Habitat Conditions and Harvest

Abstract: Analyse de la taille des populations de canards pilet et de leur succes reproducteur en relation avec les conditions de l'habitat au printemps (mares temporaires dans les prairies de nidification), en hiver (precipitations en Californie) et la chasse

Assessing the diet of dingoes from feces: a comparison of 3 methods

Abstract: I assessed diet of the dingo (Canis familiaris dingo) from 2,495 fecal samples using frequency of occurrence of prey types, relative weight of remains of prey types, and biomass of ingested prey types. There were no significant differences between methods in ranking prey types provided that _70 fecal samples/ month were analyzed. The widely used frequency method that is used to understand what and relatively how much is eaten is justified in diet studies of dingoes and other carnivores. Only the biomass ingested method allows an evaluation of the biomass or numbers of particular prey species that are eaten. For dingoes, and probably also for other carnivores, objective adjustments need to be applied to account for differences in size between juvenile and adult large prey species and for differences in the proportion of each age class

Investigating Observer Bias in Aerial Survey by Simultaneous Double-Counts

Abstract: Ajustement du comptage aerien de chevaux et d'anes sauvages dans les Territoires du Nord Australie par une methode de double comptes simultanes par 2 observateur comptant les groupes d'animaux le long du meme transect

Resource Partitioning between Sexes in White-Tailed Deer

Abstract: We tested resource partitioning between sexes of white-tailed deer (Odocoileus virginianus) by analyzing spatial and temporal distribution of each sex on the George Reserve, Michigan. Mean overlap of sexes by season was approximately 56%. Overlap was greatest during severe weather in January and least during fawning in May. Areas of concentration of each sex shifted between seasons. Females showed greater dispersion than males. There was differential use of habitats by the sexes at some seasons. Differential use of habitats was greatest when spatial overlap of sexes was highest, and vice versa. Differential use of space and habitats, in conjunction with differences in diets and diet quality, help explain the apparent lack of competition between sexes. J. WILDL. MANAGE. 53(2):277-283 An unexpected outcome of manipulations of the enclosed white-tailed deer population on the George Reserve, Michigan, was that recruitment rate was negatively correlated with number of females, but was independent of the number of males (McCullough 1979). Social factors could be ruled out because recruitment responded differently at the same population size before and after an overshoot of carrying capacity following the initial introduction (McCullough 1984:216-217), and this result was repeated in a recent overshoot experiment (D. R. McCullough, unpubl. data). Given that resources were the limiting variable, one would have expected that density per se, irrespective of sex, would be important because resources are depleted by the feeding of both sexes. Apparently, resource partitioning between sexes must exist on the George Reserve if competition for resources among females is more direct than competition between females and males. Studies of sexual segregation in ungulates have emphasized the hypothesis of reduction of competition for resources first put forward by Darwin (1871) and elaborated by Selander (1966, 1972) for birds. Spatial segregation of the sexes in the nonbreeding season is well known in ungulates (Darling 1937, Dasmann and Taber 1956, Welles and Welles 1961). Also, differences in diets between sexes have been reported by Takatsuki (1980) in sika deer (Cervus nippon), and Shank (1982) in bighorn sheep (Ovis canadensis). Jackes (1973), Watson and Staines (1978), and Bowyer (1984) reported that females occupied better habitat than males, and Staines and Crisp (1978) and Staines et al. (1982) reported that females selected more nutritious for-

Survival Rates of Bobwhite Quail Based on Band Recovery Analyses

Abstract: We present the results of a long-term (1970-85) band recovery study of northern bobwhite quail (Colinus virginianus) at Tall Timbers Research Station, Leon County, Florida. The mean annual survival rate of male quail (18.7 ? 1.2 [SE] %) was significantly (P = 0.01) greater than that of females (14.3 ? 1.2%). The difference between survival of young (6-9 months old) and adults (>1 yr old) was 3 ? 2.2% and not significant. Survival rates varied significantly among years. The mean harvest was 23.3 ? 0.53%/year. Young male quail were harvested at a significantly higher rate than adult males (2% difference). There was no significant difference between harvest rates of young and adult females. Juvenile male and female harvest rates were not significantly different. However, adult females were harvested at a significantly higher rate than adult males (5% difference). Harvest varied among years. The mean annual kill (harvest rate + crippling loss) was approximately 30% for both sexes. Male and female natural mortality were approximately 52 and 56%, respectively. There was evidence of additivity of hunting and natural mortality for this population harvested in late winter. Our long-term study provides information on the survival processes for northern bobwhite quail that can be used to enhance management of the species. J. WILDL. MANAGE. 53(1):1-6 Although research on northern bobwhite quail began in the 1920's (Stoddard 1931, Errington 1933), studies of quail survival have been limited. Sound management requires good estimates of mortality rates. Mortality for hunted species can be estimated from band recovery data using models prepared by Brownie et al. (1985). These models also provide band recovery rate estimates. Harvest rate is easily obtained if the reporting rate of bands is known. Total kill estimates follow from harvest estimates if an estimate of crippling loss is available. With these data managers can partition hunting and natural (nonhunting) mortality. A recent series of papers questions whether hunting and natural mortality are additive (Anderson and Burnham 1976, Anderson et al. 1982, Nichols and Hines 1983, Burnham and Anderson 1984, Burnham et al. 1984, Nichols et al. 1984). Most of this work applies to waterfowl, particularly mallards (Anas platyrhynchos), for which the most band recovery data are available. We report the results of a long-term bandrecovery study of bobwhite quail at Tall Timbers Research Station, Leon County, Florida. We obtained survival estimates and test the additive and compensatory mortality hypotheses (Anderson et al. 1982). W. L. Cornelius assisted with computing and J. D. Nichols reviewed an earlier draft of the manuscript. We thank present and past coworkers and many biologists and volunteers, especially wildlife technician students at Abraham Baldwin Agricultural College, for their help. This study was supported in part by Tall Timbers Research Station, Tallahassee, Florida and by an appropriation from the Congress of the United States. Funds were administered and research coordinated under the Federal Aid in Wildlife Restoration Act and through the U.S. Fish and Wildlife Service.

Effects of edge contrast on depredation of artificial avian nests

Abstract: Etude des effets de lisiere sur la predation exercee sur des nids artificiels de Bonasa umbellus places dans l'interface entre une foret de peupliers de 12 ans d'age et une de 2 ans.L'auteur conclut que la fragmentation forestiere a un grand impact sur la productivite des oiseaux et particulierement sur ceux qui nichent a terre

Denning Ecology of Black Bears in a Southeastern Wetland

Abstract: We investigated den characteristics and denning chronology of black bears (Ursus americanus) in the Great Dismal Swamp (GDS), a forested wetland in Virginia and North Carolina. We monitored 35 bears (26 F, 9 M) throughout the winters of 1984-85, 1985-86, and 1986-87. Den types included 14 ground nests, 11 excavated ground cavities, 2 ground-level tree cavities, 1 above-ground-level tree cavity, and 1 stump den. Three dens were in areas of inundation. Pregnant females entered dens earlier (P < 0.02), emerged later (P < 0.001), and denned longer (119 ? 4 [SE] vs. 78 ? 4 days) than other age and sex groups. Denning periods were among the shortest reported for black bears. Although den site availability was not estimated, dry den sites did not seem to be limited. Large den trees may not be necessary for successful denning and reproduction in certain southeastern wetlands because bears can use dense cover and microelevational factors

Analysis of variability in home-range size of the American marten

Abstract: Analyse des causes possibles de la variation de la taille des aires de deplacement pour la marte americaine a partir de donnees de la litterature.On constate une variation entre les aires des mâles mais pas de celles des femelles ainsi qu'une variation en fonction du sexe.Les variations sont egalement etudiees en fonction de la methode et de la duree d'observation