Western Kingbird  Tyrannus verticalis  This information was scanned from The Birds of British Columbia (Campbell et al.), Volume III, pages 96-101. Volumes I, II and III of The Birds of British Columbia, can be ordered electronically at: orders@ubcpress.ubc.ca from UBC Press in Vancouver, British Columbia.

 

Range Western Kingbird breeds from the southern interior of British Columbia to southern Manitoba, south throughout the western half of the United States to northern Baja California, southern Texas, and northwestern Mexico; occasionally east to southern Ontario, Arkansas, and Louisiana. Winters mainly from central coastal Mexico south to Costa Rica, with small numbers in the states bordering the Gulf of Mexico.

Status On the coast, a rare migrant and summer visitant to the upper Fraser River delta of the Georgia Depression Ecoprovince; uncommon spring transient and very rare autumn transient elsewhere in the ecoprovince, including southeastern Vancouver Island; accidental in winter. Very rare migrant and summer visitant to the southern Coast and Mountains Ecoprovince; very rare transient to Western Vancouver Island; accidental in the northern Coast and Mountains.  In the interior, a fairly common migrant and summer visitant to the Southern Interior Ecoprovince; uncommon to locally fairly common in the Southern Interior Mountains Ecoprovince; uncommon in the Central Interior Ecoprovince; rare in the southern Sub-Boreal Interior Ecoprovince; accidental in the Boreal Plains and Northern Boreal Mountains ecoprovinces.

Status Change In North America, the breeding range of the Western Kingbird, formerly known as the Arkansas Kingbird, has expanded since 1900 (Taverner 1927; Bent 1942). Planted trees, buildings, and networks of utility poles probably allowed its spread across the plains (Nice 1924). The increase in abundance and distribution in British Columbia since the mid-1940s (Munro and Cowan 1947) is best documented in the Okanagan basin. There the Western Kingbird found suitable habitat in the residential and orchard areas that replaced much of the original sagebrush and antelope-brush. It also followed highway corridors and farm clearings into higher elevations that were once dense forests (Cannings et al. 1987).  By the 1950s, the Western Kingbird was slowly expanding its range eastward across southern British Columbia (Munro 1950; Butler et al. 1986) into the east Kootenay, where it was considered a "scarce summer visitant" (Johnstone 1949). Over the next several decades it expanded its range northward along clearings and corridors into the Columbia River valley as far north as Golden. It now occurs there regularly but locally, in agricultural areas and around settlements.  Although some northward range expansion has taken place into the Central Interior and southern Sub-Boreal Interior, the species still remains an uncommon to rare summer visitant there (Munro 1945a, 1946, 1947a; Erskine and Stein 1964; Roberts and Gebauer 1992).  On the south coast, the Western Kingbird has increased its status over the past 25 years from being of irregular occurrence to one that occurs annually but in small numbers (Campbell 1969b, 1972; Weber et al. 1990).

Nonbreeding The Western Kingbird is widely distributed across southern British Columbia, including Vancouver Island. It is fairly widespread in open valley bottoms in the Okanagan, Thompson, and Kootenay regions, but is scarcer in northern portions of the west Kootenay. It is more sparsely distributed in the Cariboo and Chilcotin areas, reaching its usual northern limit south of Prince George. On the coast, transients occur infrequently along the west and east coasts of Vancouver Island, and on the southwestern mainland from the lower Fraser River valley along the Sunshine Coast north to Powell River. The species now occurs regularly in the eastern lower Fraser River valley, near Chilliwack and Agassiz.  The Western Kingbird frequents relatively low elevations, from near sea level to 200 m on the coast and up to 1,300 m in the interior. In the interior it occurs in open, hot, and dry habitats, including grasslands, sagebrush flats, open rangelands, and farmlands within the Ponderosa Pine and Interior Douglas-fir zones. It is most abundant along forest edges in the Ponderosa Pine and Bunchgrass biogeoclimatic zones. In grassland areas, it requires a few large trees or human-made structures for perch sites. It is particularly numerous along highway and road corridors, where it typically perches on fences, utility poles, or telephone lines, often in the vicinity of farm buildings. It also inhabits treed suburbs and villages. On the coast, it frequents the edges of pastures, airports, farmlands, sewage lagoons, beaches, parks, and other open areas.  Spring arrival of the Western Kingbird is two to three weeks earlier than that of the Eastern Kingbird. Migration patterns are similar for both the interior and the coast. The first migrants may arrive as early as the second week of April, but birds do not normally arrive in numbers until the end of April or the first week of May. Over 55 years, the mean and median date of first arrival in the Okanagan valley has been 29 April (Cannings et al. 1987). Peak numbers are reached by the second or third week of May.  The Western Kingbird is an early autumn migrant, with the southward movement beginning in early August and reaching a peak from mid to late August. Most birds have left the province by late August, with only a few stragglers remaining into September or later. Most migrants travel as individuals or in family groups. There is 1 winter record (see Christmas Bird Counts and REMARKS).  In the interior, the Western Kingbird has been recorded from 9 April to 4 October; on the coast, it has been recorded regularly from 15 April to 27 December.

Breeding Nests Eggs Nest Success The Western Kingbird breeds mainly in the southern interior of the province from Keremeos to Wardner, north to Spillimacheen in the east Kootenay and Castlegar in the west Kootenay, and through the Southern Interior, Central Interior, and southern Sub-Boreal Interior to Quesnel in the north and the vicinity of Riske Creek in the west. Local breeding populations occur on the coast in the Douglas-fir forests of the Pemberton valley, and in farmlands and sloughs of the upper Fraser River valley.  The Western Kingbird reaches its highest numbers in summer in the ponderosa pine forests of the Southern Interior, from Osoyoos north to Kamloops. An analysis of Breeding Bird Surveys for the period 1968 to 1993 could not detect a net change in numbers on interior routes; surveys on coastal routes for the same period contained insufficient data for analysis. Robbins et al. (1986) note that British Columbia populations showed the only persistent decrease between 1965 and 1979, although that appears to have since changed. From the western region of the Breeding Bird Surveys, population trends of the Western Kingbird show an increase in numbers between 1966 and 1988 at an average annual rate of 1.6% (Sauer and Droege 1992).  Few Western Kingbirds breed above 1,200 m elevation. In the Southern Interior, the open coniferous forests of the valley bottoms and adjacent benchlands are dominated by ponderosa pine. The dominant ground cover is bluebunch wheatgrass. In that environment, 50% of the Western Kingbird nests were in woodlands that had been altered by humans, while another 30% were in open forest situations (n = 922).  The adaptability of the Western Kingbird is revealed by its use of 40 habitat classes within the basic habitat types. The most frequently used classes were cultivated farmland (21%; n = 778), orchards or vineyards (14%), big sage shrubland (9%), arid rangeland (9%), and open ponderosa pine stands (8%), followed by rural and suburban sites (8%). In British Columbia, most nest sites were found in association with roadsides (31%; n = 407), gardens (13%), and open hillsides (10%).  In the interior, the Western Kingbird has been recorded breeding from 9 May (calculated) to 11 August; on the coast, it has been recorded from 11 May (calculated) to 11 July.

Nests:  Most nests (84%; n = 1,138) were situated on power poles. Nests were built behind transformers; on crossbars between brackets, wires, and insulators; or on other fixtures on the pole itself. Other sites included a wide variety of living and dead coniferous and deciduous trees and bushes; ledges in buildings, including houses, barns, sheds, garages, and cabins, as well as bridges; and cliff faces. Munro (1919, 1927) and Green (1928), referring to the Okanagan valley in British Columbia, state that the Western Kingbird used abandoned Northern Flicker nest holes (also Pinkowski 1982) and American Robin nests, the decayed top of fence posts and trembling aspens, and the eaves troughs of houses. The heights of 1,075 nests ranged from ground level to 45 m, with 73% recorded between 6 and 9 m. Nests were mainly bulky, untidy cups of grasses (93% of nests), string (15%), twigs (13%), plant fibres, and remains of rootless and fortes, along with at least 24 other natural and human-made materials.  Eggs: Dates for 659 clutches ranged from 9 May to 25 July, with 52% recorded between 4 and 26 June. Sizes of 107 clutches ranged from 1 to 5 eggs (1E-8, 2E-8, 3E-28, 4E-57, 5E-6), with 53% having 4 eggs. Bent (1942) reports occasional clutches of 6 or 7 eggs in the United States. The incubation period in British Columbia is 18 to 20 days.  Nest Success: Of 29 nests found with eggs and followed to a known fate, 21 produced at least 1 fledgling, for a nest success rate of 71%.  Young: Dates for 443 broods ranged from 1 June to 11 August, with 55% recorded between 25 June and 6 July. Sizes of 157 broods ranged from 1 to 5 young (1Y-8, 2Y-31, 3Y-63, 4Y-53, 5Y-2), with 74% having 3 or 4 young. The nestling period in British Columbia is 16 to 19 days. There is evidence of double-clutching. In the Okanagan valley, 1 brood fledged on 19 June and a second brood, in the same tree but in a different nest, fledged on 11 August (Cannings et al. 1987).  Brown-headed Cowbird Parasitism: Cowbird parasitism was not found in British Columbia in 259 nests recorded with eggs or young. Friedmann and Kiff (1985) and Smith (1972) note that the Western Kingbird is rarely recorded as a host. British Columbia data further support the tentative designation of the Western Kingbird as a rejector species (Rothstein 1975). As Friedmann et al. (1977) mention, the "paucity of observed cases of natural parasitism agrees well with this rejector behaviour of the Western Kingbird."

Remarks Anderson (1914) reported an early brood of three young Western Kingbirds in the Okanagan valley on 3 May 1913. It is likely this nest was a misidentified Say's Phoebe (Cannings et al. 1987).  The Western Kingbird and Eastern Kingbird occur sympatrically over much of the southern interior of British Columbia. However, the Eastern Kingbird tends to be found in thicker, wetter riparian forest and at higher elevations, while the Western Kingbird favours lower, drier, more open areas with larger and taller trees. In Manitoba, the Western Kingbird usually nests in sites having fewer but larger trees than the sites chosen by the Eastern Kingbird, and its nests are placed higher than those of the latter species (MacKenzie and Sealy 1981). The two species will nest close to each other in gardens, along road corridors (e.g., Richter Pass; Campbell and Meugens 1971), and around farmhouses where a mixture of favourable habitats occur.  Since the Western Kingbird also breeds in tall bushes and trees adjacent to transportation corridors, it is frequently a victim of highway mortality (Barkley 1966; Campbell 1984f).  In late autumn, especially October and November, Western Kingbirds should be carefully scrutinized because of the possibility of confusion with the Tropical Kingbird (q.v.), which occurs as a vagrant from the south at that time. We have not included the record of a single bird seen during the following Christmas Bird Count because convincing details were lacking: Victoria 21 December 1963-1 (Anderson 1976b).  For additional life-history and breeding habitat information, see Bent (1942), Blancher and Robertson (1984), and MacKenzie and Sealy (1981).