Aves (Birds): Ciconiiformes, Accipitridae

Aves (Birds): Ciconiiformes, Accipitridae White-tailed kite (Elanus leucurus) Potential Occurrence: Nesting Likely to Occur

Status: (nesting)

Federal: none

State: Fully Protected

Other: G5 S3

Species Description: Photo: B.L. Sullivan Medium-small hawk, total length 32–38 cm with long white tail. Sexes similar in size but females have darker backs than males (Hawbecker 1942, JRD). Conspicuous in good light are large, black scapulars and marginal coverts on an otherwise gray back, and black under wing coverts near bend in wing. Adults white underneath and gray on back from crown to upper tail coverts, with red eyes. Juveniles have buffy streaks on breast and head, and gray with white-tipped (scalloped) feathers on back, with yellow eyes. Short yellow legs. Wings long, somewhat pointed, and relatively thin. Long tail extends well beyond primaries when perched, unlike closely related Black-shouldered Kite (Elanus caeruleus) (Clark and Banks 1992). In flight, can be confused with adult male Northern Harrier (Circus cyaneus), but latter has large black patch on underside of primaries and a markedly different hunting style. Kites hunt by hovering 5–25 m above ground, whereas harriers course lower to the ground and rarely hover at heights typical for kites. While hunting, kites are easily identified by their size, bright white color, and hovering. (From Dunk 1995)

Distribution:

Present distribution is largest in species’ known history and may still be expanding. Breeding range stronghold in North America is California, with nearly all areas up to w. Sierra Nevada foothills and southeast deserts occupied…In California observed sporadically throughout most of state in winter (Small 1994). (From Dunk 1995)

[In California] Common to uncommon, yearlong resident in coastal and valley lowlands…(From Zeiner 1990)

Life History & Threats:

Yearlong diurnal, and crepuscular activity. Apparently not migratory, but Binford (1979) found some movements in coastal California. May become nomadic in response to prey abundance (Dunk and Cooper 1994). Forages from a central perch over areas as large as 3 sq km (1.9 sq mi) Warner and Rudd 1975). Seldom hunts more than 0.8 km (0.5 mi) from nest when breeding (Hawbecker 1942). Henry (1983) found mean breeding home range to be 0.57 sq km (0.2 mi). Generally not territorial, but nest site may be defended against crows, other hawks, and eagles (Pickwell 1930, Dixon et al. 1957). Defended foraging territories of about 0.10 sq km (.04 sq mi) in winter from red-tailed hawks and northern harriers (Bammann 1975). Communal roost used in nonbreeding seasons (Waian and Stendell 1970). Territory size a function of prey and competitor abundance (Dunk and Cooper 1994). Monogamous; breeds from February to October, with peak from May to August. Average clutch 4-5 eggs, range 3-6. Female only incubates, for about 28 days. Young fledge in 35-40 days. During incubation and nestling period, male feeds female, and supplies her with food to feed the young. Usually single brooded; occasionally 2 broods. Preys on rodents that may be harmful to agricultural crops. Nest may be robbed by jays, crows yellow- billed magpies, raccoons, and opossums. Great horned owls may prey on adults and young. (From Zeiner et al 1990)

[Degradation of habitat is] A significant threat to populations, especially loss of nest trees and foraging habitat…egg collectors surely reduced populations in early 1900s, at least locally. Communal roost disturbance has also caused local abandonment (JRD). Degree of sensitivity to disturbance at nests is unknown. (From Dunk 1995)

Habitat & Habitat Associations:

General Habitat

Generally occurs in low elevation grassland, agricultural, wetland, oak-woodland, or savannah habitats. Riparian areas adjacent to open areas also used. Specific plant associations seem unimportant… Topography flat to steep. Lightly grazed or ungrazed fields generally support larger prey populations and are thus more suitable. Intensively cultivated areas also used. (From Dunk 1995)

… rarely found away from agricultural areas. Inhabits herbaceous and open stages of most habitats mostly in cismontane California…Uses herbaceous lowlands with variable tree growth and dense population of voles (Waian and Stendell 1970). (From Zeiner et al 1990)

Nesting Habitat

Nest trees range from single isolated trees to trees within relatively large stands (>100 ha). Nest tree/shrub species extremely variable, from shrubs <3 m tall (e.g., Atriplex and Baccharis) (Stendell 1972) to large trees >50 m tall (e.g., Sequoia sempervirens and Picea sitchensis) (JRD) …Nest trees from 3 m to 50 m tall. Trees may be isolated or parts of contiguous forested areas. Most nests are on habitat edges and are placed in upper third of trees. Nest tree species variable; more than 20 species used (see Pickwell 1930, Dixon et al. 1957, Wright 1978)…(From Dunk 1995)

Nest placed near top of dense oak, willow, or other tree stand; usually 6-20 m (20-100 ft) above ground (Dixon et al. 1957). Nest located near open foraging area…Substantial groves of dense, broad-leafed deciduous trees used for nesting and roosting. (From Zeiner et al 1990)

Roosting Habitat

Communal roosts in fall and winter are generally in small stands of trees (isolates) (Waian and Stendell 1970, JRD), but have been observed in open fields on the ground (Clark and Wheeler 1989) and in orchards (Dixon et al. 1957, Waian 1973, A. Erichsen pers. comm.). Again plant associations not important for roost sites; wide variety of associations used. Important features of roost-sites are unknown… Roosts generally in trees or tall shrubs, but recorded < 1 m from ground in sugar cane fields (Clark and Wheeler 1989). (From Dunk 1995)

Uses trees with dense canopies for cover…Substantial groves of dense, broad-leafed deciduous trees used for nesting and roosting. (From Zeiner et al 1990)

Foraging Habitat

Prefers ungrazed grasslands (Bammann 1975, JRD), wetlands dominated by grasses, and fence rows and irrigation ditches (with residual vegetation) adjacent to grazed lands (Bammann 1975). (From Dunk 1995) Forages in undisturbed, open grasslands, meadows, farmlands and emergent wetlands. (From Zeiner et al 1990)

Conceptual Basis for GIS Model Development: All habitats in the Study Area are potential habitat for this species. We mapped the following types of habitats:

Nesting Habitat: All areas with trees (i.e., coniferous forest, broadleaf upland forest, and cismontane woodland vegetation types).

Possible best nesting habitat was identified as dense, broad-leafed deciduous trees (i.e., broadleaf upland forest (mixed, mixed montane or single dominant deciduous hardwoods) with a canopy cover of >70 %).

Foraging Habitat: grasslands

Note that plant associations are not an indicator of roosting sites and were not mapped

Potential Occurrence in the Galbreath Wildlands Preserve: Protection status for this species applies to nesting individuals.

Habitat: White-Tailed Kites nest in dense forest, most often at the edge of open ungrazed grasslands, farms and wetlands. Nesting habitat quality is good in the Galbreath Wildlands Preserve but limited due to the low amount of foraging habitat (Figure 74). Grasslands are most abundant in areas north of the Preserve, making densely wooded areas of the northern Preserve the most likely to support nesting Kites.

Nearest Occurrence:

Documented Occurrences in the Galbreath Wildlands Preserve: This species has not been documented in the Study Area. To our knowledge, no surveys have been conducted.

Nearest Occurrence to the Galbreath Wildlands Preserve: The White-Tailed Kite has not been reported to occur in USGS quads adjacent to the Study Area.

Summary: We anticipate that nesting White-Tailed Kites are “Likely to Occur” in the Preserve because they are known to occur in nearly all areas between the coast and Sierra Nevada foothills, and good potential nesting habitat occurs in the Preserve.

References

Dunk JR. 1995. White-tailed Kite (Elanus leucurus), The Birds of North America Online . Accessed 2010 Jul 28.

Zeiner DC, Laudenslayer WF, Mayer JE Jr., and White M, eds. 1988-1990. California's Wildlife. Vol. I-III. Sacramento: California Depart. of Fish and Game.

Species Account Description: Linden Schneider & Emily Harvey