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Calocitta formosa

White-throated Magpie-Jay

  • Order: Passeriformes
  • Family: Corvidae

Authors: Jesse M. S. Ellis

Identification

Summary

The white-throated magpie-jay is a large blue, black and white corvid. Its name is derived from the long blue, white-tipped tail, reminscent of that of a magpie. Blue above and white below, the species has a black necklace, variable black patterning on the face, and a curling black plume originating just above the nares.

Similar Species

The white-throated magpie-jays is most similar in appearance to its close relative, the black-throated magpie-jay (Calocitta colliei). The two overlap only in a narrow zone in west-central Mexico, but they can be told apart readily by two features.

First, the central retrices of the tail of the black-throated magpie-jay are highly elongated and somewhat floppy at their tips, resulting in a streamer-tailed appearance when flying. Secondly, as the names suggest, white-throated magpie-jays have a white throat bordered by a black necklace, while black-throated magpie-jays have an entirely black throat and a bluish or whitish triangle extending along the malar stripe. Hybrids in the contact zone have been described.

Vocalizations

White-throated magpie-jays are one of the most notably vocal species where they are found, and their vocal talents are incredible. As such, a list of vocalizations specific to white-throated magpie-jays is nearly impossible to produce. However, at least 14 functionally distinct classes of vocalizations have been described, and some of these are used much more frequently than others.

Mobbing calls are a harsh raah, raah, raah, or rah-rah-rah-rah-rah. These vary in both rate and call length depending on the nature of the threat; longer calls are given at higher rates in response to high-threat predators.

Aerial predator alarm similar to mobbing call (rahrahrah). When given all nearby magpie-jays will dive into heavy cover. This vocalization is usually produced when a raptor surprises a magpie-jay. Sometimes produced in response to low-flying Turkey Vultures (Cathartes aura).

Raptor alert calls variable, but generally soft, even, and somewhat higher-pitched. Magpie-jays give these rarely when they detect a high-flying raptor.

Soft alert calls consist of quiet notes produced when a low-threat object already discovered shifts positions or approaches a magpie-jay. Oop, up, ip, tuk, kuk, produced singly or in pairs.

Loud predator alert calls make up the bulk of the magpie-jay repertoire. They are given in low-threat alarm contexts or toward other species, usually by males. A wide range of sounds are produced in this context: more common variants in Costa Rica include: peeoo, kee-pow, pupupup-pow, prrreeeet, whoop. Such calls may be produced as the jay flies toward a car, human, dog, coyote, guan, or perched raptor. Males also produce such calls while patroling their home ranges, especially in the hour before dawn, occasionally in near-dark conditions (i.e. early dawn chorus).

Adult begging: both males and females may produce loud plaintive vocalizations that are identical to the begging of fledglings. Females in particular sit on nests before and during incubation and may beg at rates of over 10 calls/minute for several hours. Begging may increase in tempo as a group member approaches with food, and may culminate in a rapid series, terminated by a gargling moan as the female is fed.

Social chirring: Another commonly heard vocalization is produced when a female and her mate are coordinating a nesting attempt. These calls are probably given during pair formation as well. The two individuals (and occasionally other group members) move nervously near each other, producing a medium range chirr-chirr-chirr-chirr or tszerr-tszerr-tszerr-tszerr. Often given during nest-building.

Similar calls may be produced with less intensity when two group members or neighbors interact, and more intense variants are also given when two groups have a territorial border encounter.

White-throated magpie-jays produce a harsh squealing distress call when constricted. In the field this call was recorded occasionally during banding activities, but also when a group female was caught by the breeding female near the nest.

Like some other New World Jays, male magpie-jays will sing softly in three contexts: during courtship, when they fluff up their feathers, erect their crest and raise their tale and sidle along a branch; in dominance encounters, rarely, in a similar fashion; and occasionally toward apparent threats, such as humans, during which they usually do not dance but may hold their head high, tail down, and crest and neck feathers erect. Songs are not phrased like in many other passerines, but a near-continuous, barely audible warbling, which may include mimicry and sounds very unlike the rest of the repertoire.

Nonvocal Sounds

Few non-vocal sounds. Close recording of loud alert vocalizations reveals stuccato pops before some notes. Given their close relationship to Brown Jay (Psilorhinus morio) these sounds may be mechanical sounds generated by furcular sacs, although this has not been examined in specimens. Whether these should be defined as non-vocal is unclear.

 

Detailed Description (appearance)

Generally, both sexes are similar, but some minor sex differences exist in C. f. pompatus (Langen 1998). Some geographic variation across described subspecies.

Both sexes: Bill, eyes, and legs black. Wings light grey-blue, upper-tail coverts, back and nape more vibrant light blue. Central two pairs of retrices similar blue and very long, outer retrices dark above, black below, with long white tips, grading in size to form a deep diamond or wedge-shaped tail when spread, blue with white tips above. Belly and undertail coverts white, throat white, chest crossed by black necklace. Black from necklace runs up sides of neck, forming a black border separating white throat and cheeks from blue nape. Auriculars also white with small black patch beneath. Cheeks white, often with a very light blue cast.

Age and Sex Differences: Age and sex seem to interact to influence pluamge in magpie-jays, at least in Costa Rican populations. Young birds (fledglings) of both sexes (?) may lack black borders on the neck and may have an entirely white nape. As both sexes age, black becomes a more prominent part of the facial plumage, but older females tend to become much darker than older males. Adult males may have bi- or tri-colored crests, white at the base and tipped with black, or blue and black in some cases. They also tend to have white nares and eyebrows. Older males may have noticeable black borders on the neck, but younger males may lack this, and have an incomplete black necklace. Adult females tend to have entirely black crests, nares, and mostly black eyebrows, though they often have a white or blue patch above the eye. Older females may have more prominent black borders on the neck, and thicker necklace, and a larger ear-patch.

Bare Parts

Bill black. Eyes black. Legs black.

Measurements

Mass

Adults of C. f. pompata in Guanacaste, Costa Rica, ranged from 183g-219g (mean 199g) in weight.

Linear

The tail, which is sexually dimorphic, ranges from 17.5cm to 19.7cm (mean 18.6cm). Tarsus averages 45.4mm (42.8-53.1).  Culmen length averges 32.3mm, width 11.9mm, and depth, 13.7mm. Wing chord averages 18.7cm (17.0-19.7cm). Crest length is variable, averaging 6.7cm, but ranging from 5.0cm to 8.5cm.

Molts

No comprehensive information on molts. Three multi-year studies only focused on nesting period (February-July). Early during the breeding period some males observed molting out tattered central retrices, but little evidence of wing-molt from banding during this period.

Geographic Variation

No information available - Contribute

Systematics

While magpie-jays (Calocitta) have long been treated as a distinct genus, their affinities, especially with Brown Jay (Psilorhinus morio) have been up for some debate. Within the Corvidae, they belong to the New World Jays. They have long been allied with Cyanocorax, usually as a sister taxon (Hope 1989; de los Montero and Cracraft, 1997; Saunders & Edwards, 2000), but the relationship of Psilorhinus and Cyanocorax has been unstable. The most recent findings place Calocitta as the sister taxon to Psilorhinus, with this clade nested within what is currently defined as Cyanocorax and related to a suite of South American Cyanocorax, as opposed to any of a number of Central American species (Bonaccorso and Peterson, 2007; Bonaccorso et al., 2010). The overall relationship of this clade to Cyanocorax raises the possibility that both genera will be subsumed into a greater Cyanocorax.

 

Hybridization

The white-throated magpie-jay has been documented to hybridize with two species, both close relatives. Reports exist of hybrids with black-throated magpie-jay (Calocitta colliei) in Jaliscon, Mexico. More rarely, C. formosa appears to hybridize with its sister genus, Psilorhinus. A specimen almost certainly with P. morio has been documented from near Tuxtla Gutierrez, Chiapas, Mexico (Pitelka et al. 1955) and in Guanacaste, Costa Rica a mixed pair was observed raising young (Elena C. Berg, personal communication).

Recommended Citation

Jesse M. S. Ellis. 2010. White-throated Magpie-Jay (Calocitta formosa), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=514796