Killing Predators Research Articles

Biologically active compounds from natural and marine natural organisms with antituberculosis, antimalarial, leishmaniasis, trypanosomiasis, anthelmintic, antibacterial, antifungal, antiprotozoal, and antiviral activities

The biologically active compounds derived from different natural organisms such as animals, plants, and microorganisms like algae, fungi, bacteria and merine organisms. These natural compounds possess diverse biological activities like anthelmintic, antibacterial, antifungal, antimalarial, antiprotozoal, antituberculosis, and antiviral activities. These biological active compounds were acted by variety of molecular targets and thus may potentially contribute to several pharmacological classes. The synthesis of natural products and their analogues provides effect of structural modifications on the parent compounds which may be useful in the discovery of potential new drug molecules with different biological activities. Natural organisms have developed complex chemical defense systems by repelling or killing predators, such as insects, microorganisms, animals etc. These defense systems have the ability to produce large numbers of diverse compounds which can be used as new drugs. Thus, research on natural products for novel therapeutic agents with broad spectrum activities and will continue to provide important new drug molecules.

Protecting Small Livestock and Predators Alike: Early Successes

Wildlife-livestock conflict is an ongoing challenge for both livestock production and conservation efforts. Predator kills of livestock are a serious economic concern for most ranching operations. In particular, small livestock such as sheep and goats are vulnerable to native predators including mountain lions and coyotes. Despite this challenge, livestock can be a powerful tool for habitat restoration and biodiversity conservation in disturbance-adapted landscapes such as coastal California. In 2014 and 2015 we used 1,400 goats to graze habitat in the Santa Lucia Mountains, California. To prevent wildlife-livestock conflict, we tested a livestock protection strategy that combines several methods: night penning goats within a double, portable electric mesh fence; using two guarding dogs inside the pen with the goats; monitoring predators with wildlife camera-traps placed on the fence’s periphery; and placement of the pen near the herders’ camp. Despite a predator-rich environment, no goats were lost to predators, and the only predator captured on the wildlife camera-traps over 161 nights was a single coyote. Often, when lions or other predators depredate livestock, the animal is lethally removed to prevent further depredation events. Preventing predators from killing livestock protects both livestock and predators.

More bark than bite? The role of livestock guarding dogs in predator control on Namibian farmlands

AbstractThe conflict between predators and livestock farmers is a threat to carnivore conservation. Livestock guarding dogs are promoted as a non-lethal, environmentally friendly method to mitigate this conflict. As part of a farmer–carnivore conflict mitigation programme, the Cheetah Conservation Fund breeds Anatolian shepherd (also known as Kangal) dogs to protect livestock from predators. During 2009–2010 we interviewed 53 commercial and 20 subsistence Namibian farmers that are using 83 such dogs. Fewer commercial and subsistence farmers reported livestock losses to predators during the most recent year of guarding-dog use compared to the year before dogs were introduced. All subsistence farmers, but not all commercial farmers, ceased killing predators during the most recent year of guarding-dog use. All farmers ceased killing cheetah Acinonyx jubatus and leopard Panthera pardus during this year, and one dog killed a single cheetah. Conversely, dogs and farmers killed more black-backed jackals Canis mesomelas between them in the survey year than the farmers reported killing in the year before acquiring dogs. Two of the dogs reportedly killed non-target carnivore species, and 15 killed prey species. Thus our results challenge the categorization of livestock guarding dogs as a non-lethal conflict mitigation method. We suggest that the conservation status and body size of wild carnivores relative to the size of the guarding dogs be considered before introducing dogs to protect livestock. Additionally, corrective training for dogs that chase or kill non-target species should be implemented, especially where farmers value these species or where non-target species are threatened.

Human–tiger Panthera tigris conflict and its perception in Bardia National Park, Nepal

AbstractHuman–wildlife conflict is a significant problem that often results in retaliatory killing of predators. Such conflict is particularly pronounced between humans and tigers Panthera tigris because of fatal attacks by tigers on humans. We investigated the incidence and perception of human–tiger conflict in the buffer zone of Bardia National Park, Nepal, by interviewing 273 local householders and 27 key persons (e.g. representatives of local communities, Park officials). Further information was compiled from the Park's archives. The annual loss of livestock attributable to tigers was 0.26 animals per household, amounting to an annual loss of 2% of livestock. Livestock predation rates were particularly high in areas with low abundance of natural prey. During 1994–2007 12 people were killed and a further four injured in tiger attacks. Nevertheless, local people generally had a positive attitude towards tiger conservation and were willing to tolerate some loss of livestock but not human casualties. This positive attitude indicates the potential for implementation of appropriate conservation measures and we propose mitigation strategies such as education, monetary compensation and monitoring of tigers.

Buying time for colony mates: the anti-predatory function of soldiers in the eusocial aphid Ceratovacuna japonica (Homoptera, Hormaphidinae)

Eusocial aphids produce sterile individuals (soldiers) that specialize in colony protection. Killing predators is often considered the main function of soldiers. In this study, we tested the effect of harassment by soldiers of a eusocial aphid, Ceratovacuna japonica (Homoptera, Hormaphidinae), on predation by this species’ natural enemy, the larvae of Atkinsonia ignipicta (Lepidoptera, Stathmopodidae). We experimentally introduced some aphids and a predator to petri dishes and compared the survivorship of first-instar reproductives in the presence and absence of soldiers. We showed that soldiers can reduce the rate of predation on their colony mates without killing the predators. When predators encountered soldiers, they did not attempt to prey on them. Instead, they evaded them and often started to make a nest by spinning silken threads. The soldiers, in contrast, waved their forelegs and attacked the predator, and they sometimes succeeded in grasping the predator’s body. Because the predator used its mandibles to remove any soldier that succeeded in grasping its body, the soldier did not kill the predator. The reduction of predation was apparently caused by the delay of predation resulting from the harassment behavior of the soldiers. In eusocial aphids, a defensive strategy that delays predation may buy the soldiers’ colony mates time to reproduce or to escape from the predator.

Prey preference of snow leopard (Panthera uncia) in South Gobi, Mongolia.

Accurate information about the diet of large carnivores that are elusive and inhabit inaccessible terrain, is required to properly design conservation strategies. Predation on livestock and retaliatory killing of predators have become serious issues throughout the range of the snow leopard. Several feeding ecology studies of snow leopards have been conducted using classical approaches. These techniques have inherent limitations in their ability to properly identify both snow leopard feces and prey taxa. To examine the frequency of livestock prey and nearly-threatened argali in the diet of the snow leopard, we employed the recently developed DNA-based diet approach to study a snow leopard population located in the Tost Mountains, South Gobi, Mongolia. After DNA was extracted from the feces, a region of ∼100 bp long from mitochondrial 12S rRNA gene was amplified, making use of universal primers for vertebrates and a blocking oligonucleotide specific to snow leopard DNA. The amplicons were then sequenced using a next-generation sequencing platform. We observed a total of five different prey items from 81 fecal samples. Siberian ibex predominated the diet (in 70.4% of the feces), followed by domestic goat (17.3%) and argali sheep (8.6%). The major part of the diet was comprised of large ungulates (in 98.8% of the feces) including wild ungulates (79%) and domestic livestock (19.7%). The findings of the present study will help to understand the feeding ecology of the snow leopard, as well as to address the conservation and management issues pertaining to this wild cat.

Multi‐behavioral strategies in a predator–prey game: an evolutionary algorithm analysis

Behavioral games between predators and prey often involve two sub‐games: ‘pre‐encounter’ games affecting the rate of encounter between predators and prey (e.g. predator–prey space games,Sih 2005), and ‘post‐encounter’ games that influence the outcome of encounters (e.g. waiting games at prey refugia,Hugie 2003, and games of vigilance,Brown et al. 1999). Most models, however, focus on only one or the other of these two sub‐games.I investigated a multi‐behavioral game between predators and prey that integrated both pre‐encounter and post‐encounter behaviors. These behaviors included landscape‐scale movements by predators and prey, a type of prey vigilance that increases immediately after an encounter and then decays over time (‘ratcheting vigilance’), and predator management of prey vigilance. I analyzed the game using a computer‐based evolutionary algorithm. This algorithm embedded an individual‐based model of ecological interactions within a dynamic adaptive process of mutation and selection. I investigated how evolutionarily stable strategies (ESS) varied with the predators’ learning ability, killing efficiency, density and rate of movement. I found that when predators learn prey location, random prey movement can be an ESS. Increased predator killing efficiency reduced prey movement, but only if the rate of predator movement was low. Predators countered ratcheting vigilance by delaying their follow‐up attacks; however, this delay was reduced in the presence of additional predators. The interdependence of pre‐and post‐encounter behaviors revealed by the evolutionary algorithm suggests an intricate co‐evolution of multi‐behavioral predator–prey behavioral strategies.

Assessing age in the desert tortoise Gopherus agassizii: testing skeletochronology with individuals of known age

Eight desert tortoises Gopherus agassizii from a long-term mark–recapture study in the Mojave Desert, Nevada, USA, afforded an opportunity to examine the accuracy of skeletochronological age estimation on tortoises from a seasonal, yet environmentally erratic environment. These 8 tortoises were marked as hatchlings or within the first 2 yr of life, and their carcasses were salvaged from predator kills. Using a blind protocol, 2 skeletochronological protocols (correction-factor and ranking) provided age estimates for a set of 4 bony elements (humerus, scapula, femur, ilium) from these tortoises of known age. The age at death of the tortoises ranged from 15 to 50 yr. The most accurate protocol — ranking using the growth layers within each of the 4 elements — provided estimates from 21 to 47 yr, with the highest accuracy from the ilia. The results indicate that skeletochronological age estimation provides a reasonably accurate method for assessing the age at death of desert tortoises and, if used with a large sample of individuals, will provide a valuable tool for examining agerelated mortality parameters in desert tortoise and likely in other gopher tortoises (Gopherus).

Dig Deeper

Conservation in PracticeVolume 7, Issue 4 p. 14-20 Us or Them William Stolzenburg, William Stolzenburg William Stolzenburg is a freelance journalist currently writing a book on the ecological consequences of our fellow predators' demise.Search for more papers by this author William Stolzenburg, William Stolzenburg William Stolzenburg is a freelance journalist currently writing a book on the ecological consequences of our fellow predators' demise.Search for more papers by this author First published: 31 October 2006 https://doi.org/10.1111/j.1552-5228.2006.00014.xCitations: 3 KILLING PREDATORS STANDS as one of the most age-old and enduring forms of wildlife management. Even now, myth and politics trump ecology. Is there a way out? AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume7, Issue4October 2006Pages 14-20 RelatedInformation

Us or Them

Conservation in PracticeVolume 7, Issue 4 p. 14-20 Us or Them William Stolzenburg, William Stolzenburg William Stolzenburg is a freelance journalist currently writing a book on the ecological consequences of our fellow predators' demise.Search for more papers by this author William Stolzenburg, William Stolzenburg William Stolzenburg is a freelance journalist currently writing a book on the ecological consequences of our fellow predators' demise.Search for more papers by this author First published: 31 October 2006 https://doi.org/10.1111/j.1552-5228.2006.00014.xCitations: 3 KILLING PREDATORS STANDS as one of the most age-old and enduring forms of wildlife management. Even now, myth and politics trump ecology. Is there a way out? AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume7, Issue4October 2006Pages 14-20 RelatedInformation

Protecting egg prey from Carrion Crows: the potential of aversive conditioning

Carrion Crows, Corvus corone, are held responsible for taking the eggs and chicks of many bird species. In areas of conservation significance, intervention may be required. Traditionally, managers have attempted to control predation by killing predators, but this may not be the most effective or desirable approach. A non-lethal alternative, which might protect vulnerable eggs from damage by corvids, is conditioned taste aversion (CTA), a process in which animals learn to avoid certain foods following consumption of a toxin. CTA evolved to reduce the likelihood of poisoning but may be induced deliberately using an emetic. In this study, we attempted to train wild-caught Carrion Crows to avoid eggs of a preferred colour, using three different doses of the emetic Carbachol. During pre-conditioning, we established each crow’s preferred egg colour (subsequently known as ‘toxic’). During conditioning, each bird was allowed access to a single Carbachol-treated ‘toxic’ egg for 4 h per day. We compared pre- and post-conditioning responses to untreated eggs of ‘toxic’ and ‘non-toxic’ colour. Crows took longer to attack untreated eggs after conditioning with Carbachol (all doses combined). This was the result of a reduction in attacks on ‘toxic’ eggs after 2 h, while there was no change in attacks on ‘non-toxic’ eggs. The total number of eggs attacked after 4 h did not change following conditioning, however the amount of egg consumed increased. This resulted from an increase in the number of ‘non-toxic’ eggs attacked and consumed. There was no change in the attack or consumption of ‘toxic’ eggs. The highest Carbachol dose tested (381 mg kg −1 body weight) created aversions as described above for the combined results. We have shown that Carbachol can be used to manipulate crow predation on eggs in captivity. Future work should focus on captive and field trials based on a dose of 381 mg kg −1 body weight. CTA could provide a more effective and more desirable alternative to culling for controlling predation by corvids on eggs of conservation significance. Such techniques might have widespread application to predation situations across a range of animal species worldwide.

Mites on birds: Comment from Harper & Randall

Mites on birds: Comment from Harper & Randall

Secondary poisoning of stoats (Mustela erminea) in a South Island podocarp forest, New Zealand: implications for conservation

This study tested the efficacy of secondary poisoning using Talon 20 P™ (20 ppm brodifacoum) in bait stations for killing predators in a New Zealand podocarp forest. Nine of 10 resident radio-tagged stoats (Mustela erminea) were killed after poisoning operations that killed mice (Mus musculus), ship rats (Rattus rattus) and brushtail possums (Trichosurus vulpecula). Possums were an important source of the poison, with six stoats dying 1–2 weeks after scavenging on poisoned carcasses. New male stoats rapidly invaded the poisoned areas, but few were killed because poisoned carcasses were scarce. Most resident stoats died before possums were poisoned in other New Zealand trials when Talon 20 P was hand-broadcast. Prey abundance is potentially an important determinant of efficacy of the method, so pulse baiting is likely to be more successful than press (sustained) baiting operations for controlling stoats. Use of bait stations delayed indirect poisoning of stoats, but reduced risks to non-target native species compared with hand-broadcast operations. Talon 20 P poisoning operations using bait stations could be an especially useful way of restoring New Zealand’s mainland communities of native biota because several species of predators are killed in the same operation, but potential risks to non-target native wildlife and humans should be intensively researched before the method is routinely used. This research also demonstrates the potential hazards of the new anticoagulant poisons like brodifacoum to conservation of small native predators elsewhere.

Prey diversity and selectivity of the African fish eagle: data from a roost in northern Kenya

A total of 1872 bones from a fish eagle roost at Lake Turkana, Kenya was identified and analysed to provide data on fish eagle prey and diet. The approach of this study complements field observation studies in that it provides a long‐term analysis and quantification of the diet, rather than short qualitative observations. The study found that, at least where fish is relatively abundant, fish eagles are both selective and opportunistic: selective in taking preferred fish in much greater proportions than natural availability, and also in avoiding unwanted fish regardless of abundance, but opportunistic in taking certain other species in proportion to their availability. They also show considerable selection in size and habitat preferences of prey. Non‐fish prey forms a considerable proportion of the diet, and probably represents both opportunistic hunting, possibly when conditions for fishing are poor, and killing of other predators robbing fish eagle nests.As well as describing and quantifying the fish eagle diet at Lake Turkana, data from this study suggest that further study is needed to quantify the impact of fish eagle predation on Clarias lazera, a rare, but valuable species to the Lake Turkana fishery. The study of bird roost prey remains also provides baseline data for studies of fossil microfaunal accumulations. Scatters of bones under fish eagle roosts are common in eastern Africa, and undoubtedly contribute to many of the fossil bone accumulations recovered. One of us (DM) has noted that the taxonomic and skeletal composition of the Koobi Fora roost bears a great resemblance to some of the clusters she is analysing from Olduvai Gorge. Further similar studies will provide additional data on bird roost accumulations.

Age and Condition of Deer Killed by Predators and Automobiles

We evaluated the condition of mule deer (Odocoileus hemionus) and white-tailed deer (0. virginianus) killed by mountain lions (Felis concolor), coyotes (Canis latrans), and automobiles from December through March, 1969-81 in western Montana. Predators killed prime-aged animals and automobiles killed (G = 41.4, P < 0.001) more fawns and old-aged animals. Fifty-three deer (90%) killed by automobiles were in poor condition, but only 2 (7%) deer killed by predators were in poor condition. Predator selectivity could not be inferred from the sample of deer killed by automobiles. J. WILDL. MANAGE. 52(2):316-320 The influence of predation on young and old animals and animals in poor condition is important in population dynamics. To assess selectivity, standing age structure or herd condition from a representative sample of the herd is needed. In studies that do not involve capturing and marking herbivores, hunter kills (Fritts and Mech 1981) and accidental kills (e.g., automobiles: Pimlott et al. [1969], Franzmann and Arneson [1976]) are commonly used to obtain data. Although the potential for bias in a sample of hunter-killed animals is often recognized (Frazer 1976, McCullough 1979, Downing 1980), less attention has been paid to possible biases in accidental kills. We present age structures and condition of deer killed by predators and by automobiles in western Montana, and examine possible biases in each sample. STUDY AREA Predator kills were found on mule deer winter ranges in the foothills of the Bitterroot Mountains and white-tailed deer ranges of the Swan and Clearwater valleys in western Montana. Automobile kills were collected from major highways around Missoula, Montana. Mule deer winter ranges were primarily on south-facing slopes. These areas support a foothills bunchgrass habitat interspersed with Douglas-fir (Pseudotsuga menziesii)-ninebark (Physocarpus malvaceus) and ponderosa pine (Pinus ponderosa)-savannah vegetation types (Pfister et al. 1977). White-tailed deer ranges were mostly in oldgrowth forests. The Clearwater and Swan rivers, interspersed with lakes, generally divide the This content downloaded from 157.55.39.223 on Wed, 24 Aug 2016 05:11:18 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 52(2):1988 CONDITION OF DEER * O'Gara and Harris 317 study area, and level lowlands extend to the east and west from them to meet an east-facing slope on the western edge and a west-facing slope on the eastern edge of the study area. Bunchgrass habitats of the ponderosa pine series are present in limited portions of the study area. All but 4 of the 15 habitats within the Douglas-fir series described by Pfister et al. (1977) are distributed in a mosaic pattern within the study area. The major highways where deer killed by automobiles were collected ran along rivers below mule deer winter ranges and through white-tailed deer ranges and agricultural lands.

The Economics of Sheep Predation in Southwestern Utah

Ten sheep ranches in southwestern Utah were chosen for a verification study ot sheep losses during 1972- 1975. Using the ratio of verified predator kills to total lamb carcasses discovered, total lamb loss to predators was estimated. Predation accounted for 5.8% of total lambs docked or 62% of the total lamb loss. Coyotes made 94% of all predator kills. For the 10 herds (1 Y71- 1974) direct income loss due to lamb predation averaged $2,800 per herd: for a three-herd subsample (197l- 1975) direct income loss averaged \.3,500 per herd. Applying our study rate of predation to the entire Southwest region ot Utah gave an estimate of 14,900 lambs killed by predators and a direct income loss of ‘ii419,OOO. In addition, the region suffered indirect or multiplier losses of $1,166,000 to ‘4 i ,Xi6,000 during the -l years studied. Further data needs in predation economics could be achieved by integrating predation loss, predator population, and predator control data into a standard production function model. Recent profit reductions have resulted in 10% annual decrcascs in Utah’s sheep numbers (Statistical Reporting Service lOY:-,) and have increased the sheepman’s incentive to prevent IiLestock predation losses. Simultaneously, predatorcontrol has become increasingly complex. Early predator control research ~3.4 aimed primarily at discovering methods of eradicating co) otes. the most troublesome predator (Bailey I W-F, 190X). IMore recently. financial relief through economically efficient predator control has come into increased contlict with interests promoting esthetic. recreational, and ecolo#al values associated with a viable predator population. To det’ine the magnitude of the predation problem and to pro\‘ide a data base for an economic analysis, a verit’ication study ofsheep loss was initiated in March I972 in the Cedar-City ;II~‘;I of Utah (Bowns et al. 1973a, 1973b: Davenport et al. I ‘JY’_J ). A study requiring examination of each sheep carcass was \utli~~ 4r’e rc\cxch d~,soc131t‘. Ikpartn~ent ot Range Scwncc. Colorado St~tc U~I~CI

The role of griffon vultures Gyps africanus and Gyps ruppellii as scavengers

In the Serengeti, predator kills formed from 8 to 45 % of the carcasses that griffon vultures fed upon, the remaining carcasses coming from animals that had died from other causes. But since vultures obtained only very small amounts of food from predator kills, they had to rely for their food supply chiefly on the carcasses that were derived from other causes. In the Serengeti the large proportion of migratory ungulates prevent the mammalian predators from building up to a population size that can be responsible for a large proportion of ungulate mortality. It is estimated that the mammalian predators only take about one quarter of the potential food supply available for carnivores. The remaining ungulates die from various other causes, and so provide food for scavengers which varies in abundance and location with the seasons. This is a food supply which mammalian scavengers cannot easily use but griffon vultures, with their adaptations for gliding flight, are able to exploit it. These vultures therefore exploit a basically different food supply from predators and probably evolved as scavengers of migratory ungulate populations.

FUNCTIONAL RESPONSE OF THREE SPECIES OF PHYTOSEIIDAE (ACARINA) TO PREY DENSITY

AbstractExperiments were carried out on excised leaves to determine the form of the functional response curve of the phytoseiid predators Amblyseius largoensis (Muma), A. concordis (Chant), and Typhlodromus floridanus (Muma), to increases in density of the prey, Oligonychus punicae (Hirst). The curve for each species was curvilinear to a plateau from prey densities of 1 to 70/arena, the average number killed/24 hours at the plateau being 8.5/female for A. largoensis, 5.5/female for A. concordis, and 2.0/female for T. floridanus. From prey densities of 70–300/arena, there was an accelerated rise to another plateau, in which the average number of prey killed in a 24 hour period was double that of the first plateau.Detailed analysis of A. largoensis at a density of 200 prey/arena showed the effect to be due to a stimulation–interference component, which resulted in the predator killing several prey in close succession because of increased prey contact, and because total utilization of each was minimal. During a 1 hour period, A. largoensis captured an average of 1.25 prey/predator at a prey density of 35/arena, while at a prey density of 200/arena, 3.87 prey/predator were captured. More than four times longer was spent feeding on the first prey at a density of 35 than at a density of 200 prey/arena. During the time that the predator was hungry, it was stimulated to capture and kill interfering prey that bumped into it.The functional response curve of the three predators increased in magnitude when waterproofed paper arenas were used. Four possible reasons for this increase are discussed: reduced number of prey eggs for consumption by T. floridanus; lack of webbing, which interferes with searching; increased prey activity; and dehydration of prey, affecting their relative palatability to the predator.

Effect of Insecticides on the Green Peach Aphid, Myzus persicae (Sulzer), Infesting Burley Tobacco1

From 1958 through 1964, 24 compounds were tested in the field for control of the green peach aphid attacking burley tobacco in Kentucky. Because major aphid infestations on tobacco in Kentucky occur late in the growing season, it is often difficult to cover the plants thoroughly with insecticides when aphid control is needed. Single applications of the nonsystemic materials now recommended do not always give effective control. The systemic phosphate insecticides, dimethoate, phosphamidon, methyl demeton, and Bidrin® (3-hydroxy-N,N-dimethyl- cis -croton-amide dimethyl phosphate), give excellent control of the green peach aphid and appear particularly promising where good coverage is unobtainable. The use of carbaryl, especially in repeated applications, can result in a noticeable increase in the numbers of aphids compared with the numbers found on untreated plants. Whether this increase is caused by the killing of aphid parasites and predators or by some physiological effect of carbaryl on the plant is not known.

A Method for Sexing Blue Grouse

A method of sexing blue grouse (Dendragapus obscurus) in hand and in field has been found by the author, while studying this bird in Washington County, Idaho. With birds in hand, the method is simple, and of value where untrained personnel check the hunter's bag for sex. Sexes are differentiated by white feathers, tipped with bluish-black, around the cervical air sacs in the male, in contrast to barred grayish-brown feathers of that region in the female. The white feathers, inverted by the male in display, are found in about three rows on the upper side of the cervical air sacs and five to six prominent rows on the lower side. The feathers of the jugulum are whitish, also tipped with bluish-black, but are not as distinct as those on the sides of the neck. For Birds in Hand.-In stroking the side of the neck from the body toward the head, the feathers are artificially inverted and a male is indicated by a flash of white feathers. From inspection of thirty-two male blue grouse, in which white feathers around the cervical air sac were checked against gonads, only one was found which did not have white feathers. It was a juvenile male collected July 18, 1952. However, a smaller juvenile male collected July 10, 1952 had the sex-distinguishing white feathers, as did another juvenile male collected August 18, 1952. Sixteen of the males checked were taken by hunters during September, 1952; twelve were collected by the author and four were predator and road kills. In addition, forty-nine other males from hunters' bags showed white feathers. In these, gonads were not checked, but absence of barred feathers on head, nape, interscapulars (Ridgway and Friedmann (1946), and middle pair of rectrices were used to identify males (Pearson, 1936). Nineteen female blue grouse, whose sex was determined by inspection of gonads, failed to show white feathers when stroked along side of neck from body to head. Fifteen of these females were taken by hunters during September, 1952. Seventy-one additional female blue grouse, from the hunter kill of September, 1952, did not have white feathers in the cervical region. These females were not sexed by inspection of gonads, but by barred feathers on head, nape, interscapulars and central pair of rectrices. Since the only negative case was a juvenile male approximately six weeks old, the method is considered effective for sexing adult blue grouse in the hand during all months, and juveniles after the middle of August. For Birds in Field.-In life, the white feathers around the cervical air sac in the male frequently form a white streak along the side of the neck terminating in the shoulder region. At times the white streak is concealed. Its absence therefore is not indicative of a female. Many times, due to poor light and distance, the white streak is more easily distinguished than other sexual differences in plumage, especially when juveniles are present. In the current study, presence of the white streak has been used in the field as an aid to check sex of