|Alternative English names: None
Alternative scientific names: None
Spanish names: Urraca de Bosque Nublado (H); Chara Unicolor
(E); Chara Pinera (G)
Mayan names: Hesh
Madge and Burn list 5 subspecies: A. u. unicolor
of Chiapas (Mexico) and Guatemala; A. u. concolor
of Veracruz in Mexico; A. u. griscomi of El Salvador
and West Honduras; A. u. oaxacae of Oaxaca; and A.
u. guerrensis from Guerrero in Mexico. Others have also
been discussed (eg by Dickey and van Rossem). Monroe refers
to a number of specimens that were collected in Honduras and
discusses the geographical variation within the species.
Webber and Brown (1994) made the only major study of the
natural history of this species. Their study was done in an
area of predominantly pine oak forest in Chiapas in Mexico,
near to the Guatemalan border. This species is also found
in deciduous cloud forest, where it has never been studied
in detail. They made detailed observations almost every day
from 10th January until the 1st June, which covered most of
the breeding season. Much of their work was concerned with
social behaviour within groups, which they compared to other
Groups of adult (ie one year or older) birds ranged in size
from 4 to 9 individuals and contained both males and females.
The groups remained fairly constant throughout their observations.
The territory of one group was fully mapped and had an area
of 41 to 45 hectares; others were estimated to be of a similar
order of magnitude. Territory boundaries were defended against
The birds ate blackberries, the fruit of wax myrtle, pine
seeds and also animals such as katydids, anoles, crickets,
cicadas and a nestling hummingbird. They were often seen attacking
nests of the moth Hylesia frigida. Some human waste was also
eaten, such as discarded corn kernels, tortillas and pastry.
They mention that in previous years they had observed jays
harvesting and eating acorns in July, though it was not seen
throughout their main study period because they had not ripened.
They discus the foraging strategies of mostly feeding on the
upper sides of branches, but, when necessary, dangling beneath
a branch or taking food from thin branches whilst in flight.
They also discuss how they feed at Bromeliads.
The jays were observed roosting separately about 25m apart
near to the top of pine trees that were about 15m in height
(even if higher trees were present). They went to roost about
10 minutes or so before sundown. A table is presented, giving
interactions with other vertebrates which they mobbed or which
mobbed them, with those species that made the jays give an
alarm call or hide etc. There are also some species that were
seen to associate with groups of jays to forage.
Although most groups had more than one female and in some
groups more than one of them copulated, the authors had no
evidence that there was more than one nest per group. Most
copulations were made by what they termed the ‘primary
male’, which defended the females from other males in
the group. However, these subordinate males were seen to copulate
and it was possible that they may have fathered some of the
young. Those males that were most likely to have fathered
the young were the ones that gave most attention to the chicks.
They built their nests 5.5-13.5m from the ground in trees
6-20m high. The one nest that they handled was 40cm in outside
diameter and about 15cm deep. The inner cup was 11cm in diameter
with a lining of lichen (Usnea) about 3cm deep with a few
pine needles. All of the successful nests that they studied
were in oaks, with oak forming the main material of the nest.
They observed the jays building three nests in pine trees,
but none of them were completed. Nest-building was first observed
on January 19th. This nest was complete and the lining was
being added by the 26th January. A number of individuals within
the group would bring nesting material, though at all nests
the breeding female brought the most. Only the breeding females
laid and incubated the eggs and nestlings. All group members
are thought to have shared in the feeding of the incubating
female. They did not have the opportunity to check inside
the nests, but there were 4 nestlings in one nest, three nestlings
in two other nests and at least two in another nest. All group
members were thought to have shared in the feeding of the
young. Of five nests that they observed, only two were successful.
Eggs were estimated to have hatched in one group on 13th March
and in another on 11th March. They then fledged about 22 days
Biblioteca de Sonidas Aves de Mexico has a recording of call
Infonatura has a range map www.natureserve.org
Instituto Nacional de Ecologia has an info page which includes
a painting www.ine.gob.mx
Biotopo del Quetzal
Monroe, B. L., Jr (1968). A distributional survey of the birds
of Honduras. Ornithological Monographs No. 7. AOU.
Webber, T. and Brown, J. L. (1994) Natural history of the
Unicolored Jay in Chiapas, Mexico. Proc. West. Found. Vert.