Robert G. Anthony

Comparison of rumen and fecal analysis to describe deer diets

Rumen and fecal samples were collected simultaneously from mule deer (Odocoileus hemionus) and white-tailed deer (0. virginianus) in southeastern Arizona. Rumen samples were analyzed volumetrically and fecal samples microscopically to compare results obtained by the two techniques. Comparisons of the data acquired by these techniques show that results from microscopic fecal analysis are quite similar to those from volumetric rumen analysis. Fecal analysis appears to be a useful technique for studying deer diets in the arid Southwest. The utility of this technique for other areas and species is discussed as are sampling rates and suggestions for successful use of fecal analysis. J. WILDL. MANAGE. 38(3):535-540 The most commonly used procedure for studying food preferences of ungulates has been rumen analysis by volumetric (Dirschl 1962, Martinka 1968) or point analysis (Chamrad and Box 1964) methods. These methods of rumen analysis have been compared and evaluated on the basis of accuracy and time requirements by Robel and Watt (1970). When rumen samples must be collected from secretive and/or endangered species of ungulates, rumen analysis is not always a feasible technique. Consequently, biologists have often analyzed fecal samples microscopically for the remains of identifiable plant cuticles. Since every plant species has unique cuticle characteristics, and most plant cuticles are not digested in ruminant digestive processes, forage plants can be identified microscopically in fecal samples of grazing or browsing herbivores (Stewart 1965, 1967; Stewart and Stewart 1970; Adams 1957; Hercus 1960; Martin 1955). This technique has been used to study food habits of cottontail rabbits (Dusi 1949), waterbuck in Africa (Kiley 1966), pocket gophers (Myers and Vaughn 1964), many African game species (Stewart 1967, Stewart and Stewart 1970), and deer (Zyznar and Urness 1969). While using fecal analysis one must assume that the epidermis of each plant species survives digestion sufficiently to be identifiable in the feces (Stewart 1970). The validity of this assumption is questionable, and results from fecal analysis have not been compared with those of other techniques. The purpose of this research was to compare the results from rumen and fecal analysis when these samples are secured from individual deer simultaneously. Our results provide information on the usefulness of fecal analysis for studying deer diets in the Southwest. METHODS AND MATERIALS Simultaneous collections of rumen and fecal samples were obtained from 13 mule deer killed by hunters in the Dos Cabezas Mountains and from 9 white-tailed deer by special collections in the Santa Rita Mountains, southeastern Arizona. Samples from male mule deer were acquired in November during the 1970 and 1971 regular hunting seasons, and samples from female whitetailed deer were taken during the summer of 1970. Rumen samples were washed and preserved in a 10 percent formalin solution, 1 Present address: School of Forest Resources, Pennsylvania State University, University Park 16802. J. Wildl. Manage. 38 (3):1974 535 This content downloaded from 157.55.39.92 on Tue, 21 Jun 2016 05:28:25 UTC All use subject to http://about.jstor.org/terms 536 RUMEN AND FECAL ANALYSIS Anthony and Smith and fecal samples were preserved in formal acetic acid (85 parts-70 percent alcohol, 10 parts-40 percent formaldehyde, and 5 parts-glacial acetic acid) until they could be analyzed.

STATUS AND TRENDS IN DEMOGRAPHY OF NORTHERN SPOTTED OWLS, 1985-2003

Abstract We analyzed demographic data from northern spotted owls (Strix occidentalis caurina) from 14 study areas in Washington, Oregon, and California for 1985–2003. The purpose of our analyses was to provide an assessment of the status and trends of northern spotted owl populations throughout most of their geographic range. The 14 study areas made up approximately 12% of the range of the subspecies and included federal, tribal, private, and mixed federal and private lands. The study areas also included all the major forest types that the subspecies inhabits. The analyses followed rigorous protocols that were developed a priori and were the result of extensive discussions and consensus among the authors. Our primary objectives were to estimate fecundity, apparent survival (φ), and annual rate of population change (λ) and to determine if there were any temporal trends in these population parameters. In addition to analyses of data from individual study areas, we conducted 2 meta-analyses on each demographic parameter. One meta-analysis was conducted on all 14 areas, and the other was restricted to the 8 areas that constituted the Effectiveness Monitoring Plan for northern spotted owls under the Northwest Forest Plan. The average number of years of reproductive data per study area was 14 (range = 5–19), and the average number of recapture occasions per study area was 13 (range = 4–18). Only 1 study area had <12 years of data. Our results were based on 32,054 captures and resightings of 11,432 banded individuals for estimation of survival and 10,902 instances in which we documented the number of young produced by territorial females. The number of young fledged (NYF) per territorial female was analyzed by testing a suite of a priori models that included (1) effects of age, (2) linear or quadratic time trends, (3) presence of barred owls (Strix varia) in spotted owl territories, and (4) an even-odd year effect. The NYF varied among years on most study areas with a biennial cycle of high reproduction in even-numbered years and low reproduction in odd-numbered years. These cyclic fluctuations did not occur on all study areas, and the even–odd year effect waned during the last 5 years of the study. Fecundity was highest for adults (x̄ = 0.372, SE = 0.029), lower for 2-year-olds (x̄ = 0.208, SE = 0.032), and very low for 1-year-olds (x̄ = 0.074, SE = 0.029). Fecundity was stable over time for 6 areas (Rainier, Olympic, Warm Springs, H. J. Andrews, Klamath, and Marin), declining for 6 areas (Wenatchee, Cle Elum, Oregon Coast Range, Southern Oregon Cascades, Northwest California, and Simpson), and slightly increasing for 2 areas (Tyee, Hoopa). We found little association between NYF and the proportion of northern spotted owl territories where barred owls were detected, although results were suggestive of a negative effect of barred owls on the Wenatchee and Olympic study areas. The meta-analysis on fecundity indicated substantial annual variability with no increasing or decreasing trends. Fecundity was highest in the mixed-conifer region of eastern Washington (x̄ = 0.560, SE = 0.041) and lowest in the Douglas-fir (Pseudotsuga menziesii) region of the Oregon coast (x̄ = 0.306, SE = 0.039). We used Cormack–Jolly–Seber open population models and Program MARK to estimate apparent survival rates of owls >1 year old. We found no differences in apparent survival rates between sexes except for 1 area (Marin), which had only 6 years of data. Estimates of apparent survival from individual study areas indicated that there were differences among age classes with adults generally having higher survival than 1- and 2-year-olds. Apparent survival rates ranged from 0.750 (SE = 0.026) to 0.886 (SE = 0.010) for adults, 0.626 (SE = 0.073) to 0.886 (SE = 0.010) for 2-year-olds, and 0.415 (SE = 0.111) to 0.860 (SE = 0.017) for 1-year-olds. These estimates were comparable to survival rates from previous studies on the subspecies. We found evidence for negative time trends in survival rates on 5 study areas (Wenatchee, Cle Elum, Rainier, Olympic, and Northwest California) and no trends in survival on the remaining areas. There was evidence for negative effects of barred owls on apparent survival on 3 study areas (Wenatchee, Cle Elum, and Olympic). Survival rates of adult owls on the 8 Monitoring Areas generally were high, ranging from 0.85 (SE = 0.009) to 0.89 (SE = 0.010), but were declining on the Cle Elum, Olympic, and Northwestern California study areas. The meta-analysis of apparent survival indicated differences among regions and changes over time with a downward trend in the mixed-conifer and Douglas-fir regions of Washington. The meta-analysis of apparent survival also indicated that there was a negative association between fecundity and survival the following year, suggesting a cost of reproduction on survival. This effect was limited to the Douglas-fir and mixed-conifer regions of Washington and the Douglas-fir region of the Oregon Cascade Mountains. We used the reparameterized Jolly–Seber method (λRJS) to estimate annual rate of population change of territorial owls in the study areas. This estimate answers the question, Are these territorial owls being replaced in this geographically open population? Point estimates of λRJS were <1.0 for 12 of 13 study areas. The analyses provided strong evidence that populations on the Wenatchee, Cle Elum, Rainier, Olympic, Warm Springs, H. J. Andrews, Oregon Coast Ranges, and Simpson study areas were declining during the study. The mean λ̂RJS for the 13 study areas was 0.963 (SE = 0.009), suggesting that populations over all the areas were declining about 3.7% per year during the study. The mean λ̂RJS for the 8 monitoring areas for the Northwest Forest Plan was 0.976 (SE = 0.007) compared to a mean of 0.942 (SE = 0.016) for the other study areas, a 2.4-versus-5.8% decline per year. This suggested that owl populations on federal lands had higher demographic rates than elsewhere; thus, the Northwest Forest Plan appeared to have a positive effect on demography of northern spotted owls. Populations were doing poorest in Washington, where apparent survival rates and populations were declining on all 4 study areas. Our estimates of λRJS were generally lower than those reported in a previous analysis (λ̂RJS = 0.997, SE = 0.003) for many of the same areas at an earlier date. The possible causes of population declines include but are not limited to habitat loss from timber harvest and fires, competition with barred owls, and weather patterns.

Nesting Success and Habitat Relationships of Burrowing Owls in the Columbia Basin, Oregon

Etude de la reproduction chez Athene cunicularia et plus particulierement du succes de la couvaison en fonction du site de nidification. De plus, les influences de la disponibilite en nourriture et de la pression de predation sont examinees

Effects of road management on movement and survival of Roosevelt elk

Road closures frequently are used to manage for Rocky Mountain elk (Cervus elaphus nelsoni), but no studies have evaluated the effects of limited vehicle access on movements and survival of Roosevelt elk (C. elaphus roosevelti). We studied movements and survival of female Roosevelt elk before Road Management Areas (RMA) were designated, and during limited vehicular access from 1991 to 1995. The Bureau of Land Management (BLM) instituted a limited-vehicle access program on 35% of the study area in 1992. We found a reduction in core area size (P = 0.002) and home range size (P = 0.077) during limited vehicle access. There was also a reduction in daily movement of elk (P = 0.0001), and there was a negative correlation between daily movements and percent association of elk home ranges with RMA. There was an increase in survival rate (P = 0.03) during the limited-vehicular access period compared to the pre-RMA period, and survival rate declined following the removal of the gates (P = 0.05). Our data suggest that limited-vehicular access reduces human disturbance that results in reduced movements and poaching (increased survival) of Roosevelt elk. Such methods should be considered for other elk populations.

Foraging Strategies of Glaucous-Winged Gulls in a Rocky Intertidal Community

Foraging strategies of Glaucous-winged Gulls (Larus glaucescens) were studied in rocky intertidal habitats of the western Aleutian Islands, Alaska. Daily foraging activity was most intense at maximum low tide, and was concentrated in the lowest intertidal zones available to the birds. Barnacles (Balanus glandula) and mussels (Mytilus edulis) comprised most of the gulls diet during neap low tides, but these species were almost entirely abandoned during spring low tides in favor of sea urchins (Strongylocentrotus polyacanthus), chitons (Katharina tunicata), and limpets (Collisella pelta and Notoacmaea scutum). Sea urchins, chitons, and limpets, which had positive prey selection indices, were most abundant in the lower intertidal zones; barnacles and mussels, which had negative prey selection indices, were most abundant in the upper zones. Gulls also generally selected the larger individuals from each prey species, although sea urchins larger than the commissural bill width were avoided and limpets were selected in proportion to availability. Variation in prey availability also occurred among study areas with varying densities of sea otters (Enhydra lutris). With increasing depression of invertebrate prey by sea otter predation, gulls fed on a more diverse prey resource, and they switched to neritic fishes under intense sea otter predation. Preference experiments were conducted in the field, in which the common species and sizes of prey were made equally available to foraging gulls, thus eliminating search and capture times. In comparison with natural food choice, where sea urchins were most preferred, chitons became most preferred. We suggest that chitons are infrequent in natural diets because they adhere more strongly to the substratum than do sea urchins. Benefits of selective foraging were determined by comparing the net rate of energy gain of simulated random foragers with energy gained by selection of intertidal zones, prey species, and prey sizes. Observed selection patterns provided increased energy as gulls became more selective, and averaged 155% more than that obtained by the simulated random foragers. Results of the study support the two main predictions of optimal foraging theory in that (1) foraging patches (intertidal zones) and diets were selected such that net rates of energy gain were maximized, and (2) gulls became more selective foragers when energetically more profitable prey were more available.

Are barred owls displacing spotted owls

Abstract Barred Owls (Strix varia) have expanded their range into the Pacific Northwest, and anecdotal evidence suggests that they may be displacing the federally threatened Northern Spotted Owl (Strix occidentalis caurina). Our objectives were to describe the current status of Barred Owls in Oregon and compare occupancy of Spotted Owls in historic Spotted Owl territories before and after Barred Owls were first detected in those territories. Between 1974 and 1998, we estimated that 706 different Barred Owl territories were located in Oregon. From 1989–1998 an average of 60 new Barred Owl territories were located in Oregon each year. In Spotted Owl demographic study areas in Oregon and Washington, Barred Owl detections increased at Spotted Owl territories from 1987–1999. Occupancy of Spotted Owl territories declined after Barred Owls were detected within 0.80 km of the territory center. When Barred Owls were detected 0.81–2.40 km from Spotted Owl territory centers, occupancy of Spotted Owls was only marginally less than at territories without Barred Owls. This suggests that the frequency and intensity of interactions between the two species is negatively associated with distance between them. Our results suggest that land managers and regulatory agencies should regard Barred Owls as a threat to Spotted Owls, particularly if Barred Owls continue to increase in number as they have during the past 25 years. ¿Está Strix varia Desplazando a Strix occidentalis caurina? Resumen. Desde su expansión hacia el Pacífico Noroeste, existe evidencia anecdótica de que Strix varia podría estar desplazando a S. occidentalis caurina. Nuestros objetivos fueron describir el estatus actual de S. varia en Oregon y comparar la ocurrencia de S. occidentalis caurina en sus territorios históricos antes y después de que S. varia se detectó por primera vez en dichos territorios. Entre 1974 y 1998, estimamos que se confirmaron 706 territorios diferentes de S. varia en Oregon. Entre 1989 y 1998, se localizaron en promedio 60 nuevos territorios de S. varia anualmente. En áreas con estudios demográficos de S. occidentalis caurina en Oregon y Washington, las detecciones de S. varia en territorios de S. occidentalis caurina se incrementaron entre 1987 y 1999. En comparación con territorios sin S. varia, la ocupación de territorios de S. occidentalis caurina disminuyó luego de que se detectaron individuos de S. varia a menos de 0.80 km del centro del territorio. Cuando se detectaron individuos de S. varia entre 0.81 y 2.40 km del centro de los territorios, la ocupación de éstos fue sólo marginalmente menor que en territorios sin S. varia. Esto sugiere que la frecuencia e intensidad de la interacción entre las dos especies está asociada con la distancia entre ellas. Nuestros resultados sugieren que las autoridades ambientales y de regulación deben considerar a S. varia como una amenaza para S. occidentalis caurina, particularmente si los números de S. varia se siguen incrementando como en los últimos 25 años.

THE RELATIONSHIP BETWEEN HABITAT CHARACTERISTICS AND DEMOGRAPHIC PERFORMANCE OF NORTHERN SPOTTED OWLS IN SOUTHERN OREGON

Abstract We used data from Northern Spotted Owl (Strix occidentalis caurina) territories to model the effects of habitat (particularly intermediate-aged forest stand types), climate, and nonhabitat covariates (i.e., age, sex) on owl reproductive rate and apparent survival in southwestern Oregon. Our best model for reproductive rate included an interaction between a cyclic, annual time trend and male breeding experience, with higher reproductive rates in even years compared to odd, particularly for males with previous breeding experience. Reproductive rate was also negatively related to the amount of winter precipitation and positively related to the proportion of old-growth forest near the owl territory center. Apparent survival was not associated with age, sex, climate or any of the intermediate-aged forest types, but was positively associated with the proportion of older forest near the territory center in a pseudothreshold pattern. The quadratic structure of the proportion of nonhabitat farther from the nest or primary roost site was also part of our best survival model. Survival decreased dramatically when the amount of nonhabitat exceeded ∼50%. Habitat fitness potential estimates (λ̂h) for 97 owl territories ranged from 0.29–1.09, with a mean of 0.86 ± 0.02. Owl territories with habitat fitness potentials <1.0 were generally characterized by <40%–50% old forest habitat near the territory center. Our results indicate that both apparent survival and reproductive rate are positively associated with older forest types close to the nest or primary roost site. We found no support for either a positive or negative direct effect of intermediate-aged forests on either survival or reproductive rate.

Spotted owl home-range and habitat use in young forests of Western Oregon

Abstract To assess spotted owl use of young forests, we studied home-range sizes and habitat-use patterns of 24 adult northern spotted owls (Strix occidentalis caurina) on 2 sites in the Oregon Coast Range: the Elliott State Forest (ESF) and state forest lands in the Northern Coast Range (NCR). Conifer forests at ESF were characterized by a mixture of old, mature, and pole-sized conifer, similar to other areas occupied by spotted owls in western Oregon, USA. In contrast, conifer forests at NCR were younger than most other sites occupied by spotted owls in western Oregon and consisted primarily of conifers <80 years old. Broadleaf forest also was abundant (approx 22%) at both ESF and NCR. We used an information–theoretic approach and Akaikes Information Criterion (AIC) to evaluate a priori hypotheses about spotted owl home-range sizes and habitat-use patterns on our study areas. Considering previous knowledge about habitat requirements of the species, we predicted that owls occupying sites with fewer old conifer stands would have larger home ranges and that owls would select the oldest and most structurally diverse forest available for foraging and roosting. Our top model for evaluating home-range sizes indicated that the proportion of older conifer forest within the home range best explained the variability in home-range sizes. Although we found considerable variation in home-range size among owls, home-range sizes at ESF generally were smaller than home-range sizes at NCR, and home ranges at both sites were smaller than those reported for other study areas in western Oregon. Habitat-use patterns also varied widely among owls both within and between sites. Models containing distance to the nest tree, proximity to nearest forest edge, and proximity to nearest broadleaf-forest edge were the most parsimonious models for distinguishing owl locations from random points. On average, owl locations at both study areas were closer to ecotones between broadleaf forest and other cover types and farther from forest–nonforest ecotones than random points. Overall, we did not observe strong selection or avoidance of any cover type, although owls at ESF showed greatest use of older conifer forest while owls at NCR showed greatest use of broadleaf forest. Use of these habitat configurations and cover types by spotted owls had not been well documented prior to our study. The predictive power of our models was not great, however, indicating that factors in addition to those we included in our analysis may have influenced owl habitat-use patterns at our study areas. Based on our results, we recommend that managers at these sites maintain existing old and mature conifer forest, broadleaf forest, broadleaf-forest edges, and forested riparian areas as owl habitat; avoid timber harvest in core use areas; and plan the size of areas managed for spotted owls to reflect actual home-range and core-area sizes for owls in those forests.

Estimation of animal abundance when capture probabilities are low and heterogeneous

Obtaining reliable estimates of abundance or relative abundance under conditions of low numbers of captures and recaptures is crucial to properly assess population status of species that are of management concern; however, these characteristics make estimation difficult. We applied the commonly used jackknife (Burnham and Overton 1978, 1979) and moment (Chao 1988) estimators of abundance to capture-recapture data from northern flying squirrel (Glaucomys sabrinus) populations that had low (p ≅ 0.10), heterogeneous, capture probabilities and low densities (approx 2 squirrels/ha). The jackknife estimator selection procedure, higher-order jackknife estimators, and moment estimator were sensitive to the number of trapping occasions. These estimators tended to have low precision. Comparisons of estimators suggested specific, lower-order jackknife estimators performed well. Monte Carlo simulations corroborated results from field data. The moment estimator tended to have low bias, but the high root mean square error made the estimator less reliable than lower-order jackknife estimators. First- and second-order jackknife estimators tended to be the most reliable (low bias and precise) estimators when the number of trapping occasions (t) was ≥ 12. However, confidence interval coverage (% replications in which the constructed confidence interval included true N) was low with the first-order jackknife estimator, reflecting the negative bias of the variance estimator. We improved confidence interval coverage by an ad hoc adjustment to the variance estimator; coverage with the adjusted estimator approached the nominal 90% level at t ≥ 12. Reliable estimates of abundance can be achieved under conditions often encountered in field studies (small N and low, heterogeneous, capture probabilities) with lower-order jackknife estimators, a modification of the variance estimator for the first-order jackknife estimator, and ≥ 12 trapping occasions

BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES

Because sea otters (Enhydra lutris) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles (Haliaeetus leucocephalus) in the Aleutian Islands, Alaska, USA. We studied the diets, productivity, and density of breeding Bald Eagles on four islands during 1993-1994 and 2000-2002, when sea otters were abundant and scarce, respectively. Bald Eagles depend on nearshore marine communities for most of their prey in this ecosystem, so we predicted that the recent decline in otter populations would have an indirect negative effect on diets and demography of Bald Eagles. Contrary to our predictions, we found no effects on density of breeding pairs on four islands from 1993-1994 to 2000-2002. In contrast, diets and diet diversity of Bald Eagles changed considerably between the two time periods, likely reflecting a change in prey availability resulting from the increase and subsequent decline in sea otter populations. The frequency of sea otter pups, rock greenling (Hexagammus lagocephalus), and smooth lumpsuckers (Aptocyclus ventricosus) in the eagles diet declined with corresponding increases in Rock Ptarmigan (Lagopus mutus), Glaucous-winged Gulls (Larus glaucescens), Atka mackerel (Pleurogrammus monopterygius), and various species of seabirds during the period of the recent otter population decline. Breeding success and productivity of Bald Eagles also increased during this time period, which may be due to the higher nutritional quality of avian prey consumed in later years. Our results provide further evidence of the wide-ranging indirect effects of sea otter predation on nearshore marine communities and another apex predator, the Bald Eagle. Although the indirect effects of sea otters are widely known, this example is unique because the food-web pathway transcended five species and several trophic levels in linking one apex predator to another.