Eastern Kingbird

Tyrannus tyrannus



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Figure 2. Annual cycle of breeding and migration of Eastern Kingbird in New York.

Molt schedules assumed from data given in Dwight 1900. Thick lines show peak activity; thin lines, off-peak.

Figure 7. Growth of nestling Eastern Kingbirds.

Kansas. Data from Murphy 1981 and 1988.

Figure 8. Adult Eastern Kingbird feeding a fledgling a dragonfly.

Example of large whole prey being fed to young. Credit: Peter Riley.

Eastern Kingbird nest with eggs.

Nests often highly exposed because of position on canopy edge or on dead snag. Evidence suggests preference for use of very low nests placed on horizontal limbs well out over water.

© Peter Dunwiddie, Washington, United States, 2 July 2017
Eastern Kingbird nest, Oregon.

Nest relatively large; often seems disheveled, but sturdy. Exterior composed principally of small twigs, coarse roots, dry weed stems, and sometimes strips of bark. Softer material (willow catkins, and cottonwood and cattail more common toward inside. Collected Harney Co., OR. 18 June. Ruler is in cm.; photographer Rene Corado.

Eastern Kingbird eggs in nest.

Egg color is whitish, and marked around blunt end with ring of brownish, irregular spots of varying size. Clutch size is variable; between 2-5 eggs.

© Kent McFarland, Ontario, Canada, 5 July 2004
Eastern Kingbird clutch, Pennsylvania.

Philadelphia Co. PA. 2 June. Ruler is in cm.; photographer Rene Corado.

Adult female Eastern Kingbird on nest.

Only females have brood patches and incubate.

© Cos van Wermeskerken, British Columbia, Canada, 9 July 2017
Adult female Eastern Kingbird on nest.
© Howard Patterson, Maryland, United States, 7 June 2017
Eastern Kingbird feeding nestlings.

Nestlings are fed by both sexes.

© Jerry Case, New York, United States, 25 June 2016
Eastern Kingbird feeding fledglings.

Young remain completely dependent on parents for food for at least 2 wk after fledging. Entire family unit normally remains together.

© Steve Kinsley, Ontario, Canada, 26 July 2016


Pair Formation

Timing varies geographically; as early as late April in Florida (52), but most pairs formed by late May to early June at northern latitudes and high elevations. Generally occurs rapidly after females arrive, but some late-arriving birds may not pair until 2 to 3 wk after first pairs form. Older birds with experience together may be paired by first week of May (MTM).


May begin soon after pair formation or be delayed 2–3 wk for pairs that form in early May. Reasons for delay probably energy-related as arthropod populations are still low in May in most locations and threat of poor weather high (16).

First/Only Brood per Season

Laying dates for first clutches vary across geographic range. In Florida, as early as first or second week of May (101). In Kansas (9), New York (9), and Ontario (6, 7), laying generally peaks by first week of June. In Manitoba, most first clutches by about second week of June (152), while at high elevation sites in eastern Oregon laying of first clutches peak between second and third weeks of June (MTM, unpublished data).

Within populations, average date for first clutches varies among years by up to 2 wk: cool and/or wet weather delays laying (11; MTM, unpublished data). Within populations, individuals differ in egg-laying dates often by 3 wk. Evidence from a single breeding period in Kansas suggested that small females breed first (12), possibly because of energy advantages of small size (see 159 for theory). Laying date of first clutches becomes progressively earlier with female age (160), and despite age-related changes, laying date of different females is repeatable (sensu 161) across years (160).

Second Brood per Season

No evidence of second broods if first nest fledges young. Blancher and Robertson's (162) report of a second brood was most likely related to loss of fledglings by the pair immediately after fledging. Female may lay up to 4 clutches in a single season if successive replacement nests fail (MTM). Limit to a single brood/season is presumably related to the long period over which young are fed by parents after leaving nest (see Parental Care).

Nest Site

Selection Process

No data, but female primarily responsible for selection of nest site. However, males have been observed leading females within trees and positioning his body in potential nest sites that were later used by females (MTM). Moreover, same nest site (i.e., exact group of branches) often used in successive years when same male but different female is present (MTM), suggesting males probably sometimes influence choice of nest site.

Microhabitat; Site Characteristics

Away from aquatic environments, nests in trees in open habitats. Commonly used trees include hawthorn (Cratageus spp.), apple (Malus), elm (Ulmus), mulberry, Osage Orange (Maclura pomifera), and Norway Spruce (Picea abies) (29, 10). Prefers to nest in hawthorns in New York State (111). Preference for hawthorn, and heavy use of apple, mulberry, and Osage Orange probably based on similarity of branch structure; main branches have abundance of secondary and tertiary branches within which nests can be secured at safe distance from trunk. Numerous thorns of hawthorn and Osage Orange may deter climbing predators. Elsewhere, and less commonly, uses cottonwood and aspen (Populus spp.), oak (Quercus spp.), willow (Salix spp.), maple (Acer spp.), and Honey Locust (Gleditsia triacanthos) (152; M. Funk, personal communication; MTM). When nesting over water commonly uses American Hornbeam (Carpinus caroliniana; MTM), Northern White-cedar (Thuja occidentalis; 6), American Sycamore (Platanus occidentalis) (K. Russell, personal communication; MTM), or dead snags (M. Funk, personal communication), and in eastern Oregon, willows (15). Uncommonly but regularly uses Big Sagebrush (Artemisia tridentata) in Great Basin Desert of eastern Oregon (MTM). In British Columbia, often uses artificial structures, primarily utility poles (23% of 335 nests) (M. Funk, personal communication).

Nests are often highly exposed because of position on canopy edge or on dead snag. Nests are usually placed between 60 and 70% of actual tree height, and on horizontal limb about 0.5–2.0 m from edge of canopy (152, 10, 116). Nests in snags are placed at top (sometimes in depression such that nest is almost in a cavity (29, 114) or in a crotch adjacent to trunk. Nest height varies from near ground level to > 20 m above ground, but most nests are 2–8 m high (152, 10, 6, 111); a nest in eastern Oregon was placed on branch of willow only 1 cm above ground (MTM). Typically nests about 2 m above surrounding vegetation (163). Lakeshore nests generally placed 2.5 m above water (6) while riparian nests often placed under 2 m above water in willow dominated riparian zones (116). Choice experiments conducted with artificial nests indicate a strong preference for use of very low nests placed on horizontal limbs well out over water (116).


Construction Process

Nest is constructed by female only (17, MTM), contra C. E. Bendire in Bent (29). Most construction occurs before 1200 h, but at all times of day (MTM). Nest building requires at least 1 wk, but may extend over a 2 wk period; poor weather increases construction time (MTM). Laying of eggs in replacement clutches after failure of an initial nest took ca. 8 d in both Ontario (7.7 d ± 1.7 SE, n = 15) (162) and Oregon (8.3 d ± 0.6 SE, n = 14) (164), suggesting that replacement nests required less time to build. Use of artificial nests required marginally less time to produce a replacement clutch (6.5 d ± 0.8 SE, n = 7; t = 1.84, P = 0.082) (164). The absence of any difference in reproduction (laying date, clutch size, egg mass, length of incubation, brood size, number of young to fledge) between females that built a complete nest and those that only lined an artificial nest suggests that nest construction is not overly costly (164).

Structure and Composition Matter

Nest relatively large; often seems disheveled, but sturdy. Most nests withstand buffeting by strong winds and rain. Interior always neat and nearly circular. Exterior composed principally of small twigs, coarse roots, dry weed stems, and sometimes strips of bark. Softer material (willow catkins, and cottonwood and cattail [Typhus spp.] down) more common toward inside. Coarsest lining material is fine rootlets; other materials used to line nest include cattail, horsehair, and sometimes feathers. Twine, plastic, cigarette butts, and monofilament fishing line occasionally appear in nest. One female died when she caught her head in a loop of monofilament line that hung from nest (MTM).


Nests are slightly elliptical in shape; smaller (7.4 cm ± 0.50 SD, range 6.0–8.5) and larger (7.9 cm ± 0.44 SD, range 6.6–8.5) inner diameters are the least variable dimensions of nest (n = 20 nests from central New York). Smaller and larger outside diameters averaged 11.9 cm ± 1.26 SD (range 10.0–15.0) and 13.3 cm ± 1.36 SD (range 11.5–17.0), respectively. Inner depth (4.5 cm ± 0.68 SD, range 3.5–6.6) is roughly half that of outside depth (8.8 cm ± 2.04 SD, range 6.0–15.0). Average measurements reported by C. E. Bendire in Bent (29) for outside diameter (14.0 cm) and depth (8.25 cm) are similar, as are average inner diameter (7.6 cm) and depth (4.5 cm). The lack of information on geographic variation in nest composition, dimensions, or overall mass is worthy of further study.

Mass of nest in Oregon averaged 42.4 g ± 4.28 SE, n = 18, of which 28.6 g ± 3.96 SE was the coarse exterior material and 13.8 g ± 0.53 SE was the softer inner lining (164). No information on geographic variation in nest size.


No quantitative data. Most nests at least partially exposed to elements. Many lack overhead cover, and exposure to sun and rain can be severe (10, 165). Female essential for maintaining proper nest environment. In western New York and eastern Kansas, tend to use east side of tree (165), possibly to avoid late afternoon sun. Low placement over water may moderate temperature (6).

Maintenance or Reuse of Nest, Alternate Nests

Does not repair nests that are damaged while breeding. No alternative nests are maintained. Old Eastern Kingbird nests are rarely reused, but nest sites are often reused; has used old nests of Scissor-tailed Flycatcher (MTM) and of Baltimore Oriole (29, MTM) during same season in which they were built. At Malheur National Wildlife Refuge in eastern Oregon, ca. 10% of nests are built in the nests of other species, mainly American Robins (155). Will usurp active nests of orioles (Icterus spp.). Probable explanation for high nest reuse at Malheur National Wildlife Refuge is a limited supply of good nest sites (164).

Nonbreeding Nests

Not known.



Varying between long and pointed to very round, but most are ovate. Egg shape is consistent within a female (D. Rowe and MTM, unpublished data), and does not vary among years or clutch sizes (MTM, unpublished data).


Random samples of 1 egg from 2–3 clutches from 46 different provinces and states (n = 124 clutches) yielded following size estimates: length 24.1 mm ± 1.13 SD, range 21.7–26.8; breadth 17.9 mm ± 0.61 SD, range 16.5–19.6. Bent (29) lists average length and breadth as 24.2 mm (22.1–27.9) and 17.7 mm (16.2–19.8), respectively (n = 50 clutches). Intrapopulation variation in egg size is as large as that found at geographic scale: length and breadth in central New York ranged from 20.75–27.15 mm, and 16.20–19.25 mm, respectively (n = 267 clutches over 4 yr) (MTM). Repeatability (sensu 161) for among female differences in egg mass based on clutches of same female measured in different years in New York high (r = 0.746, P < 0.001) (160).


Eastern Kingbird has the largest relative mass (egg mass/adult mass) of all North American breeding Tyrannus (10.5%) (166). Fresh egg mass is predicted from length (L) and breadth (B) measurements in cm: mass = 0.54 (L x B2). Egg mass exhibits numerous interesting patterns of variation: (1) Egg mass may increase or decrease with laying order within clutches (9), most likely reflecting food availability. (2) Egg mass is directly correlated with total dry muscle mass of laying female, but independent of skeletal measurements (12). (3) Evidence for an inverse relationship between average egg mass and clutch size is contradictory: Data from 4 yr in Kansas (n = 173 first clutches) showed no tendency for egg mass to decline with clutch size (11), but average egg mass declined with clutch size over 5 yr in New York (n = 252 first clutches) (MTM). (4) Egg mass varies geographically; the largest eggs are produced in northwestern portion of the breeding range, but in general, is largest at high latitude locations (MTM, unpublished data). Geographic variation in body size (see 46) does not explain egg size variation among populations; large eggs may carry thermal benefits in cold environments.

Egg Composition

Shell (plus membrane), albumen, and yolk comprise 5.6%, 72.5%, and 21.9% of fresh egg mass (12). Shell (= 0.076mass0.783 [95% CI = 0.467–1.039]) and albumen (= 0.066mass1.073 [95% CI: 0.943–1.203]) scale isometrically with fresh egg mass, but yolk does not (= 0.139mass0.722 [95% CI: 0.551–0.893]); larger eggs have relatively less yolk and more albumen than smaller eggs.


Color and pattern striking. Ground color white (most common), beige, or even slightly pinkish. Marked, often rather heavily, around blunt end with ring of irregular spots of varying size. Spot size and density vary greatly among females, but in virtually all eggs spotting is much less dense at pointed end. Spot color varies from cinnamon and light brown to deep reddish browns. Color and spot patterns consistent within clutch (167). Furthermore, repeatability (sensu 161) of spot size and percent spotting in upper, middle, and lower third of eggs is highly repeatable (r = 0.716, 0.728, and 0.640, respectively; all P < 0.001) based on photographs of eggs in clutches of banded females in different years (D. Rowe and MTM, unpublished data). Freshly laid eggs are translucent and become opaque as incubation progresses. If eggs remain translucent beyond day 5 or day 6 of incubation, they are addled (MTM).

Surface Texture

All viable eggs have a smooth surface texture, and are not glossy. Eggs with grainy surface texture always prove to be inviable (MTM, unpublished data).

Eggshell Thickness

No data. Glooschcenko et al. (168) report egg shell thickness but without units. Eastern Kingbirds on acidified lakes lay eggs with thin shells (168).

Clutch Size

Based on 1,357 egg sets from across North America: 2 eggs (6.0%), 3 eggs (41.9%), 4 eggs (46.6%) and 5 eggs (5.5%) (MTM, unpublished data). Field studies generally indicate slightly smaller clutch sizes than recorded by egg sets, with average values of 3.1 ± 0.63 SD (n = 42) in western New York (9), 3.2 ± 0.58 SD (n = 903) in central New York (MTM, unpublished data), 3.7 ± 0.56 SD (n = 54) in southeastern Ontario (6), 3.3 ± 0.66 SD (n = 230) in eastern Kansas (MTM, unpublished data), 3.4 ± 0.50 SD (n = 30) from Montana (5), and 3.5 ± 0.61 SD (n = 573) in eastern Oregon (MTM, unpublished data). All aforementioned studies (except Ontario) include both initial and replacement nests. Field studies and analysis of museum egg sets indicate that clutch size increases from east to west across North America. Museum egg sets also indicate clutch size does not increase with latitude (MTM, unpublished data). The East–West difference in clutch size exists mainly because of fairly abrupt increase beginning at 100th Meridian, the traditional boundary between the more mesic eastern and the xeric western regions of North America (MTM, unpublished data). The increase in average clutch size from east to west across North America mirrors interspecific differences in genus Tyrannus (MTM, unpublished data). See also Demography and Populations: Measures of Breeding Activity.


Begins about 6 d after end of nest construction, but interval may be as short as 2 d or as long as 14 d (9) or even 21 d (169). Most eggs laid early in morning. One egg laid/d until clutch is complete, but occasionally a day is skipped between laying of penultimate and final egg in clutches of 3 and 4 (9). Electrophoretic evidence suggested intraspecific brood parasitism occurs (150), but detailed observations at over 1,000 nests in 4 other populations have never given evidence of > 1 egg/d (MTM). Eggs have appeared ≥ 2 d after completion of clutch (MTM).


Only females have brood patches and incubate (17, 21, MTM). Incubation requires 14–17 d, with modes of 15 d in New York (mean 15.4 d ± 0.75 SD, n = 21), and 14 d in Kansas (14.2 d ± 0.39 SD, n = 12) (9). Modal incubation length in Oregon is 15 d (MTM). Shorter incubation in Kansas is a product of warmer ambient temperatures in Kansas and inverse relationship between ambient air temperature and length of incubation (9). Females may begin sitting on nest before eggs appear (MTM), but incubation usually begins with laying of penultimate egg in clutches of 3–5. No quantitative information on incubation rhythms. Male does not feed female prior to or during incubation. Incubating female usually calls for male before leaving to feed. Male remains vigilant near nest until female returns (17, 24).


Young open shell from blunt end and may begin to vocalize 3–4 h before hatching. First nestling(s) often hatches late in day, followed by appearance of 2–3 more nestlings on following day. All nestlings may hatch within a few hours, but the typical pattern is for the first-hatched and last-hatched nestlings to appear about 24 apart, not uncommonly up to 48 h, and occasionally 72 h (8; MTM, unpublished data). Female either eats or disposes of shells at some distance from nest immediately after young hatch.

Hatching failure is sometimes high. In Michigan, 26% of eggs failed to hatch (37.5% of nests examined); pesticides were a possible factor (170). Entire clutch fail to hatch occasionally (Kansas: 2 of 101 clutches; New York: 11 of 681 clutches; Oregon: 2 of 369 clutches) (MTM). On average, 8% to 10% of eggs that survive to point of hatching fail to hatch (Kansas: 29 of 340 eggs; New York: 202 of 2,148 eggs; Oregon: 137 of 1,315 eggs) (MTM).

Young Birds

Condition at Hatching

Hatchlings highly altricial (blind and naked except for gray to white down). Skin color orange, and hatchlings weigh about 8% of adult body mass (mean 3.2 g ± 0.42 SD, n = 14) (43). Variability in hatching mass due to differences in egg mass (r = 0.843, P < 0.001; see Eggs). Tarsometatarsus length averages 6.4 mm ± 0.50 SD (n = 40). Respond to high-pitched sounds and gentle movement of nest by begging (MTM).

Growth and Development

Description of growth and development based on nestlings from Kansas (Figure 7; 43, 44). Orange body color of hatchlings begins to fade within a day of hatching to dark gray. The following age-specific changes occur (hatching = day 1): dotting of primaries on wings, day 2; spinal, humeral, and capital tracts darken, day 3; ninth primary (p9) emerges, day 4; eyes open, days 4–6; sheaths emerge along most feather tracts, day 5. Body mass, tarsus, and p9 grow logistically (Figure 7). Tarsae grow from 28% of adult length at hatching to adult size by day 14. Mass begins to level off at 80–90% of adult mass at about day 10 (the age when nestling activity increases and rate of primary growth peaks; Figure 7). Variation nonetheless exists and effects of size at hatching detectable throughout nestling period as small hatchlings (< 3.5 g at hatching) are lighter than large hatchlings (> 3.5 g at hatching) throughout most of growth period (165). Young often jump from nest if disturbed on day 14 when p9 is only 42% of adult size. Nest leaving occurs normally on day 16 or 17 when most young are capable of weak, but sustained flight (9). Variation in size at fledging substantial and in part related to negative influence of brood size on growth (8, 165, 44; but see 6). Variation in duration of nestling period inversely correlated with length of primaries at day 14 (9): Young in small broods often have longer primaries and fledge sooner.

Causes of Death

Almost all nestling deaths due to nest predators (8, 10, 6, 7, 141, 157, 13, 14). Adults can feed experimentally enlarged broods of 5 young (13); starvation common only when low temperatures and precipitation persist for several days (8, 141, 13). Other occasional sources of mortality include exposure to sun (165), and mites (MTM). Losses of entire nests to strong winds and thunderstorms common in Great Plains (9, 11).

Parental Care

Brooding and Shading

Brooding is done by female only (22, 27). Time spent brooding declines linearly between hatching (45–50 min/h) and day 10. Females were not observed to brood after day 10 (22), the age at which nestling body mass begins to level off and feather growth reaches maximum (Figure 7). Time spent brooding varies inversely with ambient air temperature (22), and as a consequence, declines over the course of the morning (26). Time spent shading young is independent of nestling age; females are forced to shade young on clear, sunny days when nest is exposed (22).


By both sexes. In Michigan (21) and New York (24) females fed young more often than male, but in Oregon, female fed only slightly more than male. Young fed soon after hatching (21). In Oregon among pair differences in paternal feeding rate unrelated to whether a male lost paternity (27), and difference in male feeding rate between New York and Oregon not related to paternity because frequency of extra-pair paternity equal in New York (1) and Oregon (2). Parents continue feeding young for at least 3 wk and often 4 wk after fledging (21; MTM, unpublished data).

Unless otherwise stated, description based on Morehouse and Brewer (21) and Rosa and Murphy (22). Young fed primarily insects, but during periods of either cold and wet, or hot and dry weather, parents bring fruit (MTM). One nestling fed/trip to nest. No consistent diurnal pattern to feeding (26), but observations from single nests have shown low feeding rates early in morning and at midday (Finly 1917 in 98, 171). Size of insect prey increases as nestlings age, but in general, young fed large, whole insects, mainly Coleoptera, Orthoptera, Hymenoptera, and Odonota (Figure 8) and, rarely, small frogs (MTM). Parents kill prey and remove stingers (from bees and wasps) before feeding to young. When they are abundant, odonates important nestling food item.

Studies in Michigan and New York show that feeding rate increases with age, peaking when nestlings are about 10 d old at rate of 5–6 feeding trips/nestling/h. Feeding rate per chick is negatively influenced by brood size in New York (23) but not Oregon (27). Feeding rate per chick also depressed during periods of rain and with increases in time spent watching for predators (i.e., vigilance) and moderating nest microclimate (brooding and shading young) (22). Females paired to males breeding for the first time on a territory (most likely males in first breeding season) make a greater proportion of feeding trips than females breeding with males experienced with the territory (all at least in second breeding season) (24).

Vigilance behavior is performed by both sexes, but primarily males; males in New York spent 50% of each hour perched either in the nest tree or a neighboring tree watching the nest during the nestling period (24). A trade-off exists between feeding rate and vigilance (22) and probably partly explains lower feeding rate of males than females in New York. Nest depredation is major cause of nest failure (see above) and presumably favors high vigilance. In New York, combined male and female nest attendance (vigilance, nest watching, brooding) left nest unattended for only 11% of each hour (24).

Nest Sanitation

Nestlings defecate after being fed, and both parents remove fecal sacs. Fecal sacs either consumed or carried from nest. In Oregon, fecal sac consumption declines with nestling age (26) and is greater in females than males (27), while fecal sac transport increases with brood size (26). Young defecate over side of nest by day 14 (MTM).

Parental Carrying of Young

Not known.

Cooperative Breeding

Does not occur (17, MTM). Trios of adults occasionally form, but are rarely stable; a trio in New York remained together from early in nestling period to > 1 mo after young had fledged (MTM). The fate of the third bird in next year was determined in 2 of 3 cases in which the third bird was banded and sex determined. In one case, a female returned to breed on territory where she was seen in previous year (former male and female occupants of territory failed to return). In the other case, a male established residence on adjacent territory in following year. Third birds in trios probably represent birds prospecting for a breeding site in the next year. One case of incest is known: an experienced female (> 9 yr old) bred with a son raised in previous year (MTM).

Brood Parasitism

Identity of the Parasitic Species

Brown-headed Cowbird (Molothrus ater).

Frequency of Occurrence

Frequency of brood parasitism by the Brown-headed Cowbird is difficult to assess because kingbirds usually eject cowbird eggs (172). Friedmann et al. (173) reported only 24 Eastern Kingbird clutches with cowbird eggs. Records of clutches parasitized—3 of 339 (174) and 12 of 989 (169) in Ontario; 1 of 402 at Delta Marsh, Manitoba ( 134); 0 of 213 in British Columbia (M. Funk, personal communication); and 1 of > 700 in central New York (MTM)—also suggest that cowbirds rarely parasitize Eastern Kingbirds. In western New York and eastern Kansas, however, cowbirds parasitized 4 to 13% of nests, depending on year (175). In parasitized nests, usually 1 cowbird egg/nest.

Timing of Laying in Relation to Host's Laying

Brown-headed Cowbirds normally lay eggs during the Eastern Kingbird's laying period (MTM). Quantitative data are lacking on the timing of laying of apparent parasitic Eastern Kingbirds, but single kingbird eggs have appeared more than a week before the clutch and 2–3 d after clutch completion (MTM). No records of 2 eggs appearing on same day (MTM).

Responses to Parasitic Mother, Eggs, or Nestlings

Eastern Kingbirds react aggressively toward cowbirds (174, 176). Kingbirds usually reject cowbird eggs (172), but they are rarely incubated, hatched and the young raised to fledging (98, 175). Foreign (experimentally introduced) kingbird eggs are usually ejected if they appear prior to egg-laying, but are always accepted once host female has begun to lay (167, 134).

Effects of Parasitism on Host

Nests that receive cowbird eggs often lose an egg either to ejection by cowbird (6 of 16) or egg damage (5 of 16) (175). The single cowbird fledged by kingbirds in Kansas had no influence on growth of host's 3 young (175). Intraspecific brood parasitism increases nestling competition for food but does not occur frequently enough to influence breeding patterns (MTM).

Success of Parasite with this Host

Essentially zero for cowbirds (175, 134).

Fledgling Stage

Young leave nest normally 16–17 d after hatching, but ability to maintain strong, level flight does not appear for several more days. Some broods remain within nest tree 2–3 more days. On first day, brood may move along branch only 1–2 m from nest, but with each successive day they move farther away.

Young remain completely dependent on parents for food for at least 2 wk after fledging. Entire family unit normally remains together. Maximum feeding rate during fledgling period is nearly twice that of peak rate during nestling period (21). Young may begin to take fruit and pick small invertebrates off leaves by 25 d, but continue to be fed at high rate until about 5 wk old. Parental feeding continues for about 2 more weeks, gradually declining during that time (21). Parents defend young against predators up to 7–8 wk of age. Survivorship of fledglings is generally very high (9, MTM); predation probably is main cause of fledgling death.

Immature Stage

Little known. Southward migration of all birds generally begins in mid to late August and therefore young probably begin migration within 2 to 3 wk of the termination of parental care.

Recommended Citation

Murphy, M. T. and P. Pyle. 2018. Eastern Kingbird (Tyrannus tyrannus), version 2.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.