Cooper's Hawks Research Articles

Experimental Study of Feeding Rates of Nesting Cooper's Hawks

Journal Article Experimental Study of Feeding Rates of Nesting Cooper's Hawks Get access Noel F. R. Snyder, Noel F. R. Snyder Box 21 Palmer, Puerto Rico 00721 Search for other works by this author on: Oxford Academic Google Scholar Helen A. Snyder Helen A. Snyder Box 21 Palmer, Puerto Rico 00721 Search for other works by this author on: Oxford Academic Google Scholar The Condor, Volume 75, Issue 4, 1 October 1973, Pages 461–463, https://doi.org/10.2307/1366569 Published: 01 October 1973 Article history Accepted: 15 February 1973 Published: 01 October 1973

Adaptive Mechanisms of the Raptor Pelvic Limb

THIS study presents some adaptations in the pelvic limb of six North American raptorial species. Bock and von Wahlert (1965) point out the term adaptation needs to be defined when used. I studied evolutionary adaptations as I am interested in those structural features that enable raptors to sustain a predatory role within a given environment. I am not concerned with evolutionary pathways. In this regard, I studied closely related and diverse species having similar habits. I investigated the raptorial species from both orders and four of the five families in North America (the nonpredaceous New World vultures, the Cathartidae, were omitted). The species studied were the Cooper's Hawk (Accipiter cooperii), Red-tailed Hawk (Buteo jamaicensis), Prairie Falcon (Falco mexicanus), Sparrow Hawk (Falco sparverius), Screech Owl (Otus asio), Burrowing Owl (Speotyto canicularia), and the Barn Owl (Tyto alba). I compared the raptors to one another, as well as to a nonraptorial species. A generalized species is difficult to define, but one that does not use its legs and feet for any particular activity other than walking or standing seems appropriate. I selected the domestic pigeon (Columba livia). The functional aspects of the anatomy of the birds of prey have been little studied. Garrod (1875) described the vinculum connecting the tendons of the flexor digitorum longus and flexor hallicus longus for several genera of Falconiformes. Subsequent workers (Shufeldt, 1887; Hudson, 1937; Ruggeberg, 1960) further discussed the fusion of these tendons. Shufeldt (1909) presented a very general account of the osteology of several species including A. cooperii, B. jamaicensis, and F. mexicanus. Peczely (1964) compared the thoracic vertebrae of several genera of raptors including Buteo, Accipiter, and Falco. Where possible, he related anatomical differences to the habits of the birds. Studies of the pelvic region of various genera of Falconiformes and Strigiformes were made by Hudson (1937, 1948) and Berlin (1963). Accurate determination of muscle forces has long presented a problem to morphologists. Present knowledge of muscle structure and physiology limit severely the traditional techniques of comparing muscle volumes and weights (for a review, see Gans and Bock, 1965). Eccles and Sherrington (1930) demonstrated the dangers of using the weight (and thus volume) of muscles as an indication of tension. They showed that though the medial gastrocnemius of the cat weighs 21/2 to 3 times as much as the soleus, it develops about 6 times as much tetanic tension

Nesting by a Yearling Canada Goose

A free-flying Canada goose (Branta canadensis interior), known to be just under a year old, laid a clutch of four eggs at the Patuxent Wildlife Research Center. At least half of the 2-year-old females nest at Patuxent, and almost all of the 3-year-olds nest. As far as we know, this is the first record of nesting by a yearling Canada goose. N EST1NG CANADA GOOSE * Hall and McGilvrey 835 shouldered hawks ( Buteo lineatus ), 42 Cooper's hawks, 10 marsh hawks (Circus cyaneus ), 8 sparrow hawks ( Falco sparverius), 36 great horned owls, 15 ringnecked pheasants ( Phasianus colchicus ), and 7 miscellaneous small birds. Also, a total of seven Cooper's hawks and five redtailed hawks were shot during this same period ( Meng 1951 ) . This gives an 8-year total of 123 raptors caught in pole traps. Few of these birds could be banded and released. For the 8 years, an average of 10 traps were in operation each season from mid-August through March. The Swedish goshawk trap is efficient in capturing raptors that have been lured to game farms by ovlerpopulations of birds. The data indicate that ffiis tap is more effective than pole-trapping or shoofing. Even if it were not, its use should be encouraged, for many people feel that the pole trap should be outlawed.

Nest-Robbing by Cooper's Hawks

Nest-Robbing by Cooper's Hawks

Sexual Dimorphism and Food Habits in Three North American Accipiters

THE three widespread North American bird hawks, the Sharp-shinned Hawk (Accipiter striatus velox), Cooper's Hawk (A. cooperii), and the Goshawk (A. gentilis atricapillus) differ greatly in size. In the course of studies on weight, wing area, and skeletal proportions of these three species (Storer, 1955), it became apparent that although the females of all three species average larger than the males, the sexual difference in size was greatest in the smallest species, the Sharp-shinned Hawk, and least in the largest species, the Goshawk. To determine more precisely the degree of sexual dimorphism in these three species, I measured the wing length (arc) of study skins in the collection of The University of Michigan Museum of Zoology. The series used were large enough to provide both a good estimate of variation within the species and an accurate mean. All birds measured were in adult plumage and were collected in the region between Grafton, in extreme eastern North Dakota, and Point Pelee, Ontario, Canada. The sample of the Sharp-shinned Hawk consisted entirely of birds taken in Michigan; those of the other species included birds from most of the broader area. Mis-sexed accipiters, especially Goshawks, appear to be not infrequent in collections, and I strongly suspect that a few mis-sexed specimens have led Friedmann (1950: 150-152) and possibly others to describe the variation both in measurements and plumage as overlapping more than actually will be found to be the case. Much of the mis-sexing probably results from the collectors' mistaking the paired ovaries (usual in birds of this genus) for testes. In our collections, four Goshawks sexed as males by the collectors measure 348, 357, 360, and 361 mm in wing length. All were taken in the winter months (December to February) when the gonads are small, and all have the heavy black streaking on the under parts, which is usually found in adult females. A fifth Goshawk, sexed as a female, measures 324 mm in wing length, has the fine barring characteristic of adult males, and lacks heavy black streaking. These five birds were omitted from the samples, and even so the coefficient of variation is over 10 per cent larger for both sex groups of the Goshawk thlan for those of the other species (Table 1). A Cooper's Hawk sexed as a male but measuring 261 mm in wing length and having the brownish plumage of the upper parts characteristic of adult females was also omitted from the data. The measurement data are summarized in Tables 1 and 2. Judging froim the difference between the means for males and for females and from

Survival of Ring-Necked Pheasants Released on a Wisconsin Shooting Preserve

Of 2,386 banded ring-necked pheasants (Phasianus colchicus) released under the gun and shot on a private, 1,942-acre shooting preserve in southeastern Wisconsin, 84 percent were bagged less than 1/4 mile and 95 percent less than 1 mile from their release sites. Preserve hunters harvested 50 percent of 5,441 pheasants stocked during 3 years. Each spring, about 6 percent of the releases appar- ently survived on the preserve, and 2 percent off the area, within 2 miles of the release sites. Of 93 birds bagged by outside hunters within 1.5 miles of the release area, 20 percent were preserve releases. In 3 years, 702 dead pheasants were found on the preserve. Length of time between release and death was fixed for 220 remains; 65 percent had died within 1 week of release. A calculated disappearance rate showed a total hunting loss, plus nonhunting losses of the first 2 weeks after release, of 83 percent. The rate of loss to nonhunting factors declined after 12 weeks to a stable biweekly rate which, if projected, resulted in a total annual loss of 54 percent. Of 226 known-cause deaths, release shock was blamed for 28 percent, shot wounds and predation for 29 and 42 percent, respectively. Feral cats (Felis domestica), Cooper's hawks (Accipiter cooperii), and foxes (Vulpes fulva and Urocyon cinereoargenteus) were major predators. Concentrations of newly released, pen-reared birds probably aggravated predation. Total nonhunting mortality was not fixed, but apparently was responsible, rather than egress, for the postrelease disappearance of most pheasants.

The Manner and Efficiency of Raptor Depredations on Bats

Large bat colonies such as those in the Carlsbad Caverns, New Mexico, attract many species of predators. The most significant are birds of prey, for they commonly feed on bats and are capable of taking them in flight (Bailey, 1928; Stager, 1941, 1948; Constantine, 1948; Eads, Wiseman and Menzies, 1957; Medway, 1958; Baker, 1961; Downing and Baldwin, 1961). Reptiles and carnivores, that might prey heavily on bats were they not terrestrial, are limited by the virtual inaccessibility of bats in their daytime roosts and by their flight habits. Only in a few congested bat caves are carnivores known to consume large numbers of bats. There are isolated cases of bat depredations by fish (Baker, 1961), amphibians (Kinsey, 1961; Elwell, 1962), birds other than raptores (Clay, 1959; Herreid, 1960; Wilks and Laughlin, 1961) and by rodents (Martin, 1961). Allen (1940) summarizes numerous references to fish, reptiles, birds, and mammals preying on bats and also lists spiders and ants as bat predators. Of all these, avian raptores are likely the most effective predators because when locally abundant, bats can constitute major proportions of raptor diets. Owl pellets from the Carlsbad Caverns are composed almost entirely of bat bones and fur. The number of bats captured, however, is relatively insignificant, and birds of prey are but minor threats to colonies as a whole. The lateness of the hour at which bats emerge almost eliminates them from the diets of diurnal birds, and nocturnal birds are incapable of pursuing and capturing individual bats. Therefore, raptores are a threat only for the relatively short time that bats exit en masse from a cavern entrance in the early evening. During that short time bats are extremely vulnerable. They emerge in dense streams for hours and by hundreds of thousands. In flight, bats are slow, compared to birds, and can be overtaken quickly. Yet, it is surprising that some birds are inefficient at catching bats and the number of captures versus the number of attacks varies greatly among the different species. For example, Red-tailed Hawks (Buteo jamnaicensis) and Great Horned Owls (Bubo virginianus) have difficulty at times in catching bats, and they may miss repeatedly. Accipiters and falcons, however, seldom miss and the reasons lie in the manner of attack and the nature of the bird. At Carlsbad Caverns National Park, park naturalists have had the opportunity for many years to witness bird depredations on the large colonies of Mexican freetail bats (Tadarida brasiliensis mexicana) that exit each evening from the caverns. Through the years, six species of hawks, one falcon, and one owl have been observed. They are: the Cooper Hawk (Accipiter cooperii), Sharp-shinned Hawk (Accipiter striatus), Swainson Hawk (Buteo swainsoni), Red-tailed Hawk, Ferruginous Hawk (Buteo regalis), Marsh Hawk (Circus cyaneus), Sparrow Hawk (Falco sparverius), and Great Horned Owl.

Saskatchewan Nesting Records of Cooper's Hawk

Saskatchewan Nesting Records of Cooper's Hawk

A Breeding Record of Cooper's Hawk in Alberta

A Breeding Record of Cooper's Hawk in Alberta

Additional Observations of Birds and Mammals in the Vanderhoof Region, British Columbia

Aquild chrysaetos (Linnaeus). Golden Eagle.-Recorded earlier on the basis of sight observations by local residents in winter. On June 13, 1952, a golden eagle was flushed from the ground beside the Lake District-Vanderhoof road. It was in the plumage of the second year. The eagle rose only high enough to clear the tree tops and alighted near the top of a spruce close to the road. A moment after it landed an adult female Cooper hawk, flying fast over the aspen tops, swooped down to it olice, then passed quickly out of view.

Wintering Bobwhite in Boone County, Missouri

NEW SALEM: The area contains 2,260 acres, and its nearest boundary is one mile north of Ashland. The topography is undulating and erosion has been moderate. It is considered Class III land. On the whole relatively high standards of agriculture have been maintained, though land improvements have been made solely through the farmers' initiative and have not been extensive in any year. There is a fair interspersion of crops and cover, and winter food and cover conditions are better than on adjoining lands. Evidence of predation has been negligible. There are a few Cooper's hawks (Accipiter cooperi), great horned owls (Bubo virginianus), red foxes (Vulpes fulva), minks (Mustela vison), and dogs and cats, but also there is a high buffer population of rodents and rabbits. Hunting pressure is average for this region. Unfortunately, it was impossible with available manpower to measure the hunter's kill. WEST ASHLAND: The area contains

From Field and Study

Journal Article Horned Owl Preys on Cooper Hawk Get access Gordon W. Gullion Gordon W. Gullion Eugene, Oregon Search for other works by this author on: Oxford Academic Google Scholar The Condor, Volume 49, Issue 6, 1 November 1947, Page 244, https://doi.org/10.2307/1364184 Published: 01 November 1947

Unusual Behavior of a Cooper's Hawk

Unusual Behavior of a Cooper's Hawk

Cooper's Hawk Carrying a Nest of Young Goldfinches

Cooper's Hawk Carrying a Nest of Young Goldfinches

Observations on Cooper's Hawk

In the Osage Hills of Oklahoma (Osage County) May 13, 1936, the writer and Mr. Wallace Hughes while searching for a chat's nest discovered the nest of a Cooper's Hawk, Accipiter cooperi (Bonaparte), which contained four ?ggs. The structure was made of branches about the diameter of an ordinary lead pencil, contained a very shallow bowl whose floor was lined with bark, and was located about 30 feet high in the crotch of a post oak tree. No down was observed in the nest. A study of the habits of this bird was anticipated and a burlap blind was constructed on the ground about 20 feet from the tree containing the nest. In order to record accurate observations, a camera operated by ground controls, was placed in a green box situated approximately 6 feet above and to one side of the nest. The site was visited every 3 or 4 days during the study. The eggs hatched on the 30th and 32nd day after discovery. Two of them hatched on the earlier date and two on the latter date mentioned.

Sexual dimorphism in north American hawks I. Sex organs

AbstractThe development of the gonads of the marsh hawk, Circus hudsonius, Cooper's hawk, Accipiter cooperi, and the red‐tailed hawk, Buteo borealis borealis has been investigated. The occurrence and relatively long persistence of the cortex on both testes of the marsh hawk is evidence of bilateral amphisexuality in this form. The embryonic condition of the ovaries is related to the degree of asymmetry in the adult organs. Nearly symmetrical, paired ovaries were found in three species and varying amounts of reduction of the right ovary in all others.The disappearance of the right oviduct in the ontogeny of the female red‐tailed hawk and the occurrence of accessory gonad tissue in male embryos of the same species are described and figured. The extent of reduction of the right ovary of eleven species is described, figured and classified. The following species are listed in the above order of classification: Circus hudsonius, Accipiter cooperi, Accipiter velox velox, Accipiter atricapillus atricapillus, Falco sparverius sparverius, Aquila chrysaëtos canadensis, Buteo borealis borealis, Buteo lineatus lineatus, Buteo lagopus sancti‐johannis, Cathartes aura septentrionalis, Buteo platypterus platypterus.It is concluded that two ways by which organs may disappear are realized in the right ovary and oviduct of the hawks. (1) by failure of an embryonic inductor in the case of the ovary, and (2) in the right oviduct by secondary atrophy of an originally well‐developed embryonic structure.

Destruction of Hawks in the United States

IT is remarkable that tho many ornithological associations in the United States were unable for thirteen years to prevent the Stato-encouraged slaughter of hawks in Maryland. In a short article in the Condor (1932, p. 187), Prof. A. Brazier Howell gives some indication of what the bounty payment of 50 cents for each hawk (the law was intended to apply to tho sharp-shinned and Cooper's hawks only) meant to the hawk population and to tho public purse. From a total of 7 individuals killed in 1918, the year of the passing of tho anti-hawk legislation, tho annual slaughter reached 20,081 in 1923–24, and 22,283 in 1929–30, when the bounty was repealed. In all, during the thirteen years when tho bounty was in force, 62,543 dollars were paid for 125,086 hawks. Unfortunately, the effect spread far beyond the bounds for which the Maryland legislators were responsible, for the inducement of the bounty led individuals to make a profitable business of hawk-hunting, particularly during autumn, when thousands of migrating hawks remain for short periods on passage. In the five years 1926–1930, a well-known resting ground of such migrants furnished 40,003 hawks, or 55 per cent of the total kill during that period, and a single hawk-hunter was rewarded in 1930 to tho tune of 900 dollars. It was against much opposition that Mr. E. Le Compte, the State game warden, finally succeeded in inducing the legislature to withdraw the bounty.

Bilateral ovaries in Cooper's hawk, with notes on kidney structure

Bilateral ovaries in Cooper's hawk, with notes on kidney structure

Can the Cooper's Hawk Kill a Crow?

Can the Cooper's Hawk Kill a Crow?

Kingfisher and Cooper's Hawk

Kingfisher and Cooper's Hawk