Sexual competition and aggression by adult females have been hypothesized to prompt dispersal by male white-tailed deer (Odocoileus virginianus). We observed behavioral interactions of 21 yearling males (14 dispersers and 7 nondispersers) at Chesapeake Farms during the early part of the breeding season prior to actual breeding. Interactions with adult males and females constituted a small portion of all interactions and yearling males were similarly subordinate to adults. Dispersers participated in breeding-season behaviors with yearling males more often than nondispersers did (P = 0.005), and tended to be more subordinate than nondispersers (P = 0.095). Behavioral differences related to sexual competition with other yearlings appeared to be correlated with dispersal by yearling males at Chesapeake Farms. We recommend that both sexual competition and aggression by adult females be considered in future attempts to understand the dispersal behavior of white-tailed deer.

Dispersal is difficult to measure and is often ignored in population analyses, despite its potential effect on population demographics. We studied population effects of dispersal by estimating natal dispersal, survival, emigration, and immigration of yearling, male while-tailed deer (Odocoileus virginianus) at Chesapeake Farms, Maryland. We radiomarked males to determine natal dispersal and survival and used mark-resight population estimates and telemetry data to estimate emigration and immigration. Most yearling males (70%) dispersed from their natal ranges a median distance of 6 km. Overall survival from 8 to 18 months of age was 0.44+/-0.07. Hunting accounted for most disperser (22 of 26) and philopatric male (4 of 7) mortalities. We estimated emigration as 39+/-8 yearling males and immigration as 31+/-11 yearling males. The postdispersal population consisted of a mix of immigrants and philopatric males. Movements of yearling males across management unit boundaries represented an exchange of individuals that required a landscape-level perspective when making management decisions. This is particularly true on small areas where the postdispersal population May contain a mix of immigrant and philopatric males.

To effectively manage a white-tailed deer (Odocoileus virginianus) population in an agricultural area, information regarding habitat use and selection is needed to aid in reducing crop damage. We gathered data on deer use of clover (Trifolium repens) and soybean (Glycine max IL.]) fields at Chesapeake Farms, Maryland. We surveyed soybean and clover fields to test the hypothesis that deer distribute themselves proportionally to availability of soybeans and clover fields. Clover patch height and mass were also measured to quantify the amount of use by deer. Deer density in clover fields was always higher than in soybean fields in both years of the study (1997 and 1998). Browsing by deer significantly reduced clover patch height and mass. Our data suggested that active selection of crops by deer did not occur.

We demonstrate practical field application of catch-per-unit-effort (CPUE) models, based on a new conceptual framework for CPUE developed by Bishir and Lancia (1996), to estimate (1) the antlered buck population of white-tailed deer (Odocoileus virginianus) on Chesapeake Farms (formerly Remington Farms), Maryland, from harvest data collected by deer hunters and (2) the high-elevation population of wild pigs (Sus scrofa) in Great Smoky Mountains National Park (GSMNP) from pig removals by Park employees. An advantage of CPUE estimates is that the required data can be collected by hunters. Compared to the reconstructed buck population, CPUE estimates were negatively biased but correctly revealed major increasing or decreasing trends; similar validation data were not available for the pig population. in cases of sustained-yield harvesting, CPUE estimates are probably sufficiently accurate because underestimates would lead to conservative management decisions.

We describe a harvest strategy that integrates a population dynamics model, a rationale for choosing a harvest rate, a means of implementing harvesting, and a change-in-ratio (CIR) population estimation technique. The size of the harvest is determined by selecting a proportion of the postharvest (residual) population (#) chosen between about zero and the intrinsic rate of increase in a given environment (rm), with a maximum sustained yield (MSY) at about 0 = r,/2 based on logistic growth, or about i = 0.5 based on McCullough's (1979:118, 1984) studies of the George Reserve white-tailed deer (Odocoileus virginianus) herd. The advantages of proportional harvesting are that the population stabilizes for all proportions, the location of the population along the sustained yield (SY) curve is unambiguous, and proportions are naturally self-correcting because harvests are tied to population size. Taking 2 separate single-type (sex) harvests provides a means for achieving the harvest quota and also yields a CIR population estimate based on observations of the proportion of antlered deer in the population at 3 times. The 2-stage CIR technique is robust to unequal observability, a major weakness of the traditional CIR methods. Our harvest strategy is most applicable where harvests can be controlled closely, and hunting seasons are relatively short. Field experiments are required to establish the efficacy of our harvest paradigm. J. WILDL. MANAGE. 52(4):589-595 Several components are needed to provide a framework for managing harvests of white-tailed deer to attain harvest and population goals. Among these are an underlying model of population dynamics that incorporates removals due to hunting, a rationale for choosing a harvest level, a means of implementing and controlling the removals, and a procedure to evaluate the success of the harvest strategy. Our objective is to integrate these requirements into a management paradigm based on a stock-recruitment model of population responses to harvesting (McCullough 1979:123-127, 1984), on 2 separate single-type (sex) removals during the hunting season, and on a 2-stage CIR population estimation technique (Pollock et al. 1985). We present a management paradigm, based on logic and theory that incorporates the concept of proportional harvesting. The 2-stage CIR is used to estimate population size, but any suitable estimation technique could be applied. We caution that our paradigm requires testing under field conditions. Our analysis begins with a deterministic model and then expands to consider briefly stochastic variability. Our strategy is most appropriate for herds closely controlled by managers. To support our rationale, we draw upon published literature and our experiences studying the deer herd on Remington Farms, Chestertown, Maryland. O r paradigm differs from the strategy developed by Hayne and Gwynn (1977), which uses the proportion of females in the harvest as a management objective. They reasoned that if th adult male harvest is inherently limited because hunter effort declines as males become scarce, then the female harvest could also be limited at a lower level by relating it to the male harvest. Their approach does not estimate population size or incorporate a measure of productivity, yet it has apparently been misinterpreted by some deer managers to reflect recruitment or changes in herd size (Downing 1981). Furthermore, Downing (1981) showed tha , alone, the proportion of females in the kill reveals little about the status of the herd. Our paradigm differs from Hayne and Gwynn's (1977) in that ours incorporates an estimate of the population and a measure of productivity. We thank Remington Farms and especially E. C. Soutiere and E. H. Galbreath for their encouragement and support. D. A. Adams, G. Caughley, P. D. Doerr, E. C. Franklin, and D. R. McCullough reviewed earlier drafts and provided helpful comments. This is paper 11498 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh. IPresent address: Florida Game and Fresh Water Fish Commission, Route 7, P.O. Box 440, Lake City, FL 32055.

Utility of the change-in-ratio (CIR) technique for estimating abundance of deer (Odocoileus spp.) populations was investigated by calculating the sample size requirements (n, = prehunt and n2 = posthunt) for 3 levels of accuracy (e = 0.10, 0.25, and 0.50) and a = 0.05 and by applying the technique to the deer population at Remington Farms, Maryland. The calculations indicated that a sample size of n = 1,600 was required to estimate abundance of deer populations with a skewed sex ratio (prehunt proportion of antlered bucks [P,] = 0.10) with f = 0.25. If only antlerless deer were removed from a population with a similar sex ratio and a large change in the ratio (AP = 0.20) was achieved, N, could be estimated for E = 0.25 with n = 325. Application of the technique at Remington Farms indicated that the sample sizes could be achieved for relatively high density herds in open habitat. Biases associated with applying the CIR to deer populations are discussed. J. WILDL. MANAGE. 50(1):125-129 Population estimates are an important component of deer population management, particularly when establishing harvest quotas or evaluating the impacts of previous management practices. Numerous techniques are available to estimate deer abundance, including track counts (McCaffery 1976), pellet group counts (Stormer et al. 1977), aerial counts (Floyd et al. 1979), drives (McCullough 1979), line transects (Evans 1975), remote sensing (Wyatt et al. 1980), markreobservation (Downing et al. 1977), and change-in-ratio (Hess 1985). Because most of these techniques are expensive, biased, or unproven, they have limited utility for management agencies. The CIR technique is an attractive alternative for estimating or indexing populations of white-tailed deer (0. virginianus) because few data are required to execute the method, and the precision of the estimator can be high. Only prehunt and posthunt estimates of the proportions of the population that are antlered and antlerless and the number and sex of deer killed by hunting are required to apply the CIR. Precision of the CIR depends on the prehunt and posthunt ratios and kill removals. An added advantage is the usefulness of sex ratios for establishing harvest regulations, particularly for trophy-buck production, when adjusting the sex ratio is a management goal. Our study objectives were to: (1) evaluate the theoretical precision of the estimator and to calculate the sample size requirements for a range of proportions of antlered and antlerless deer and (2) address the assumptions of the technique relative to its application. We then applied the CIR in a field example to ascertain whether the sample sizes dictated by the theoretical calculations could be achieved. We thank Remington Farms personnel, especially E. C. Soutiere and E. H. Galbreath, for their support, ideas, and encouragement. J. W. Eldrett conducted the fieldwork. Remington Arms Co., Inc., and the Natl. Rifle Assoc. provided funding. C. Powell drafted the figures. DESCRIPTION OF THE TECHNIQUE A brief description of the CIR technique follows; for more detail see Seber (1982) or Paulik and Robson (1969). We consider a closed population with 2 classes of animals, x-type and y-type. For our example, x-type are antlered and y-type are antlerless deer. If the proportion of xand y-type animals in the population changes between 2 periods due to the removal of a known number of animals (in our example by hunting), we can estimate total population size before the removal (NI) as follows: N, = R P (1) N2 P 2 where R, = the number of x-types removed (known), R = Rx + RY = the total number of animals removed (known), P, = X,1N, = the proportion of x-type animals before the removal, and

The change-in-ratio technique is a useful practical procedure for the estimation of game animal population sizes. The major problem with this technique is failure of the assumption that both types of animals are captured or sighted with equal probabilities. Here we extend the change-in-ratio technique to the case where there are two removals with emphasis on the special situation where there are two consecutive single-type removals. The advantage of this extension is that it allows an estimation procedure which is robust to unequal capture or sighting probabilities. It is also possible to test the assumption of equal sighting probabilities. Some numerical results on mean squared error of the population size estimator for the new design and the traditional design are given. The procedure is illustrated on some juvenile grass carp data collected in a small pond where the population size is known. We believe this technique is potentially useful to wildlife and fisheries biologists and that more statistical research would be beneficial.