Corvidae Crows, Jays, and Magpies
Version: 1.0 — Published March 4, 2020
Introduction
This family includes some of the most familiar birds in the world. Ravens and crows figure in the mythologies of many peoples worldwide, and they are well known for their sociality and intelligence. The family boasts the most advanced avian tool-user, the New Caledonian Crow Corvus moneduloides. Somewhat like parrots, corvids have calls that commonly are raucous and harsh, but many are capable mimics of a wide variety of other species’ syllables, sometimes strung together in a “whisper song” audible only at close range. Dismissed often as common familiar black birds, corvids include some stunningly beautiful birds; some of the magpies and treepies are among the most elegant and graceful of all the world’s birds.
Habitat
Corvids occupy virtually every terrestrial habitat on Earth, including Arctic tundra, arid deserts, urban streets, and tropical rainforest. Having likely dispersed around the world over millions of years from an Australasian core, it is odd that they never reached New Zealand or Patagonia or disappeared from them both.
Diet and Foraging
Corvids are omnivorous, opportunistic feeders. Many, such as ravens, crows, and most jays, are generalists, and some are prodigious nest-robbers; others, such as nutcrackers (Nucifraga) and Pinyon Jay Gymnorhinus cyanocephalus, specialize on extracting seeds from conifer cones, and most of the north-temperate jays are attuned to mast production, especially in oaks. Larger species, like the crows and ravens in particular and the Pica magpies, often scavenge animal carcasses. Most corvids cache excess food for later use; many have impressive spatial memories to find their caches, and some even breed primarily while using cached food.
Breeding
Corvid reproductive strategies are highly varied. Within the family, most species are monogamous, a few species are colonial, and a great many are cooperative breeders. The nests of most corvids are open cup structures built mostly of sticks placed in trees or bushes or on cliff ledges. Some species nest in cavities or burrows. Females alone incubate, but male and female (and helpers) actively participate in all other aspects of parental care. Corvids lay 1 to 9 eggs, most commonly 2 to 4. Incubation takes around 17 days, and the nestlings are generally in the nest from 15 to 45 days. Fledglings are fed by the parents for up to about ten weeks post-fledging, much longer in the cooperative-breeding species.
Conservation Status
Habitat loss, the main risk to corvids, threatens 26 species (21%; 13 NT, 8 VU, 2 EN, 2 CR, 1 EW). The Hawaiian Crow or ‘Alala Corvus hawaiiensis is extinct in the wild and completely reliant on a captive breeding program to avoid extinction. The two critically endangered species, both island endemics, are the Banggai Crow C. unicolor and Mariana Crow C. kubaryi; the latter is further imperiled by predation by introduced cats and Brown Tree Snakes Boiga irregularis. The endangered Stresemann’s Bushcrow Zavattariornis stresemanni and Flores Crow florensis both have very small ranges, the former in deep-soil areas of the cool highlands of Ethiopia and the other on the tiny Indonesian island of Flores.
Systematics History
Corvidae is one of the “crown corvoid” groups within Corvoidea (Barker et al. 2004, Driskell et al. 2007, Irestedt et al. 2008, Irestedt & Ohlson 2008, Irestedt et al. 2011). Although the position of Corvidae within this group has not always been clear (Fuchs et al. 2006c, Irestedt et al. 2008, Jønsson et al. 2008b), it is most likely sister to Laniidae plus Platylophidae (Aggerbeck et al. 2014), or to Laniidae (Reddy & Cracraft 2007, Jønsson et al. 2011). Unlike many families in the corvoid radiation, Corvidae is one of the few that has diversified extensively in the New World (Ericson et al. 2005, Bonaccorso & Peterson 2007, Bonaccorso et al. 2010), away from Africa and Australasia, the two centers of corvoid diversity.
Conservation Status
Least Concern |
66.2%
|
---|---|
Near Threatened |
6.9%
|
Vulnerable |
6.9%
|
Endangered |
2.3%
|
Critically Endangered |
2.3%
|
Extinct in the Wild |
0.77%
|
Extinct |
0%
|
Not Evaluated |
0%
|
Data Deficient |
0%
|
Unknown |
14.6%
|
Data provided by IUCN (2023) Red List. More information