L o u i s i a n a RAPBRAP I R D S TORSTORS O F P R E Y Louisiana RAPTORS Birds of Prey Louisiana RAPTORS Birds of Prey L o u i s i a n a RAPB I R D S TORS O F P R E Y Written by Donna L. Dittmann Steven W. Cardiff Richard DeMay Designed and Illustrated by Diane K. Baker Photography by Darlene Boucher Charlie Hohorst Greg Lavaty The Estuary Program would like to thank the many members of the “Protection of Habitat for Migratory and Resident Bird” Action Plan Team for their tireless support and commitment to “making things happen”. It is that support and commitment that is the strength of the Estuary Program. Louisiana RAPTORS Birds of Prey 2 Louisiana RAPTORS Birds of Prey What is a raptor? any different kinds of birds prey on other animals. For ex- Mample, pelicans capture and eat fish, flycatchers take insects, and sand- pipers probe for aquatic invertebrates. But, one group of birds stands out as the ultimate aerial predator. These are the raptors or “birds of prey,” and they all share a specialized set of characteristics that better equip them for locating, pursuing, capturing, and killing prey. Perhaps the most prominent features of most raptor species are strong legs and feet, combined with toes that are equipped with sharp, curved, and strong claws or “talons”. Talons are used as the primary weapon for capturing, gripping, and dispatching prey. Most raptors have a sharp, hooked bill, which can also be used to kill prey swiftly. More often, however, the bill is used as an efficient means to tear flesh from a car- cass. Raptors include two unrelated orders of Perhaps the most prominent features of most raptor birds, most easily separated by their general species are strong legs and feet, combined with toes daily activities: the diurnal raptors or “day that are equipped with sharp, curved, and strong hunters” (order Falconiformes, which include claws or “talons” ... vultures, hawks, eagles, and falcons) and the nocturnal raptors or “night hunters” (order Strigiformes, which include owls). In general, this distinction defines the two groups. But, of course, there are exceptions, especially among the owls, with some species actively foraging in broad daylight. This document focuses on diurnal “birds of prey” that frequent Louisiana. Charlie Hohorst Greg Lavaty 3 Louisiana RAPTORS Birds of Prey Louisiana’s diurnal raptors wenty-five species of Falconiformes have occurred in Louisi- Tana. An amazing 16 species breed, or have bred, in our state. Twelve species are regular breeders- Black and Turkey vultures, Mississippi and Swallow-tailed kites, Cooper’s, Red-shouldered, Broad-winged, and Red-tailed hawks, Bald Eagle, Osprey, Crested Caracara, and American Kestrel. Swainson’s Hawk can probably be placed in this group, but regular breeding needs further confirmation. There are a few modern nesting records for White-tailed Kite and Sharp-shinned Hawk, and there is one old nesting record of Peregrine Falcon. those species considered “resident” may not in fact spend the entire year in one place: local birds may move out and be replaced by individuals that have bred elsewhere. Move- ments are generally driven by availability of food resources. Species which rely heavily on insects and reptiles are essentially forced to Nine species, including some breeding relocate to warmer southern regions because species, are much more regular in winter or their prey becomes unavailable during the as migrants: White-tailed Kite, Northern colder northern winter months. Many raptors Harrier, Sharp-shinned Hawk, Cooper’s that depend on small rodents cannot find prey Hawk, Red-tailed Hawk, Swainson’s Hawk, in regions where snow can accumulate on the American Kestrel, Merlin, and Peregrine Fal- ground. The Northern Harrier represents con. Seven additional species are considered one extreme, because it is relatively nomadic vagrants: Northern Goshawk (one record), and shows year-to-year flexibility in finding Harris’s Hawk (a few records), Zone-tailed Hawk (one record), White-tailed Hawk (a few Red-tailed Hawk records), Ferruginous Hawk (a few records), Rough-legged Hawk (a few records), and Golden Eagle (rare fall migrant and winter visitor). Vagrants represent strays outside a species’ normal geographic distribution and, therefore, are unexpected in Louisiana; these species may occur from less than annually up to a few times per year. Only a few of the hawk species that occur in Louisiana are year-round residents. Even Greg Lavaty 4 Louisiana RAPTORS Birds of Prey Charlie Hohorst wintering and breeding sites with high prey southern portions of the breeding distribution densities. Most species, however, show much but not much beyond, and potentially winter stronger “site fidelity,” returning to the same ing side-by-side with more sedentary southern general breeding and wintering territories, breeders. In general, individuals that breed at sometimes even to the same nest, year after year. the northern extreme of a species’ range move Migrant species include some of our longest south in winter. The notable exception is the distance Neotropical migrants: Peregrine Falcon southern Bald Eagle, which breeds during the (Arctic tundra to temperate South America) winter and then moves north to spend the and Swallow-tailed Kite (southeastern United summer and fall. Some species, such as the States to Amazonia). Swallow-tailed Kite, along Broad-winged Hawk, migrate in large flocks, with Mississippi Kite and Broad-winged Hawk and circling “kettles” can number into the are referred to as “complete migrants,” mean- hundreds or thousands of individuals. These ing no individuals remain to winter in breeding birds can be observed during southbound areas. Northern populations of other species, flights following the first series of early fall such as Red-shouldered and Red-tailed hawks, cold fronts, their movement facilitated by are “partial migrants” shifting south in winter to strong tail winds. 5 Louisiana RAPTORS Birds of Prey 6 Louisiana RAPTORS Birds of Prey Charlie Hohorst In Louisiana, raptors In Louisiana, raptors are found in a year to year depending on local or larger-scale are found in a variety of variety of habitats, from dense forest to fluctuations of prey densities. For example, habitats, from dense for- open agricultural areas, coastal marshes, and species such as Red-tailed Hawk and North- est to open agricultural beaches. Peregrine Falcons even use offshore ern Harrier can be numerous one year and areas, coastal marshes, oil platforms during migration and winter then much scarcer the next on a local or and beaches. for roost and feeding sites. Distributions and regional scale depending on rodent abundance. population densities of breeding species tend In Louisiana, numbers can also be influenced to remain relatively stable from year to year by the relative mildness or harshness of the as they depend on appropriate habitat and a winter in areas to our north, which can either stable prey base. Densities of some winter- allow more birds to remain farther north or ing species can fluctuate substantially from drive more birds to the south. Greg Lavaty 7 Louisiana RAPTORS Birds of Prey Identifying Louisiana’s Diurnal Raptors ost raptors are fairly easy to pigeon-hole to general type (e.g., Mvulture, eagle, falcon, Buteo, or Accipiter) based on size, shape, and proportions. The use of genus name, as for the latter two italicized names, is frequently used to refer to more closely related and very similar-looking species in the same genus. For example, two species in the genus Accipiter, Sharp-shinned Hawk (Accipiter striatus) and Coo- per’s Hawk (Accipiter cooperi), are closely related and have very similar shapes, proportions, plumages, and behaviors. They are so similar that Raptors come in four basic body shapes... they can be positively identified to From these basics we can further refine shape species only by fairly experienced and add behaviors, such as flight style. observers who get a close look. However, they can more easily be classified into the more general category “Accipiter” type of hawk (in Louisiana “Sharp-shinned/Cooper’s hawk”) based on the combination of thin body shape, short rounded wings, long narrow tail, and long thin legs. Raptors come in four “basic body shapes”: ‘basics’ we can further refine shape and add long broad wings and broad tail (eagles, vul- behaviors, such as flight style, to narrow down tures, Buteo, Osprey), shorter rounded wings our choices and identify a raptor to species. and long tail (Accipiter), long rounded wings The size range of most raptor species and long tail (harrier, caracara), and long varies because of size differences between the pointed wings (kites and falcons). From these sexes (“reverse sexual size dimorphism”- fe- Four basic body shapes of raptors. Golden Eagle Cooper’s Hawk 8 Louisiana RAPTORS Birds of Prey Northern Harrier Mississippi Kite males are larger than males). However, in the may be several additional molts and inter- field such differences are not often appreci- mediate-looking plumages over a period of ated unless a male and female are perched several years prior to attaining adult plumage. together, such as a pair at a nest. Notable For example, the Bald Eagle has an extended exceptions are species in the genus Accipiter, plumage maturation period and does not which exhibit pronounced size dimorphism: attain adult plumage until the fifth year. In a the larger female Sharp-shinned is essentially few species (e.g., American Kestrel), plumage the same size as the smaller male Cooper’s. In of males and females is different. this case, size is a very important identification A Red-shouldered Hawk character. displaying adult plum- As would be expected for such highly age. specialized hunters, most raptor species are clad in relatively camouflaged plumage (black, browns, grays, and white) that helps them blend in with their surroundings; a few species are somewhat more colorful, with bluish or reddish patterning.