BIRDS: Scrub or California Jay
The scrub (or California)
jay (Aphelocoma coerulescens, Fig. 1) is distinguished
by its crestless head, olive-gray back, and white
throat, outlined in blue. Its head, tail, and wings are
blue. Calls are harsh, raspy, and varied, often in
series of ones or twos. It belongs to the same family (Corvidae)
as the other jays, magpies, and crows.
Scrub jays are found in
the western United States, parts of Mexico, and in
central Florida. Although they do not migrate long
distances, they do move to lower elevations in winter.
Scrub jays commonly
inhabit the oak and brush-covered foothills of the
mountains, timbered canyons, river bottoms, oak-lined
sloughs and creeks, as well as the shade trees and dense
shrubbery of residential areas.
Beal (1910) reported that
the diet of the scrub jay consisted of 73% plant and 27%
animal matter. The plant matter was about one-third
fruits and berries, and two-thirds acorns, nuts, and
grain. Nuts and acorns are often stored or hidden for
later use, though it is debatable how many hiding places
jays remember. The animal matter varied greatly, and
included insects, spiders, snails, and small
vertebrates, including bird’s eggs and nestlings.
Nests are usually found on
brush-covered hillsides or in creek bottoms in low
bushes, shrubs, and trees. Most nests are located near
water, but sometimes they may be found up to a mile (1.6
km) away. Egg laying occurs from early March through
June, with the peak occurring in April. Usually 4 to 6
eggs are laid. Incubation lasts about 16 days and the
young are able to leave the nest in about 18 days. Scrub
jays do not flock to the degree that crows or starlings
do. Jays usually feed alone, but where populations are
high, they may form nearly continuous lines when flying
to and from a food source.
Damage and Damage Identification
Jays are omnivorous and
therefore may damage several agricultural crops such as
nuts, fruits, grains, peas, corn, and berries. They also
take insects, small mammals, reptiles, and eggs and
young of gamebirds and songbirds. Jays have a pronounced
preference for fruits. Cherries, plums, prunes, pears,
figs, grapes, and other fruits are often pecked and
eaten. Depredations on almonds, pecans, and pistachios
can be severe.
2. Scrub jays can be taken by the use of a rat snap
trap. Bait the trap with a nut or nut meat and set as
Scrub jays are classified
as migratory nongame birds in the Code of Federal
Regulations. They may be controlled only under a permit
from the US Fish and Wildlife Service.
Damage Prevention and Control Materials
netting over fruit trees, vines, and gardens to exclude
jays from the immediate area.
devices are only moderately effective in protecting
crops from scrub jays. Almond and pistachio growers
commonly use gas cannons, Av-Alarm® devices, and
shooting to frighten or disperse jays.
Repellents and Toxicants
Jays can be
taken by using conventional rat traps baited with a
shelled or unshelled almond or the meat of half an
English walnut (Fig. 2). The best location for the rat
trap is on a vertical limb of a tree. Nail it high
enough in the tree to be out of reach of small children.
Beneath the vertical limb there should be a horizontal
limb that is frequented by jays. Fasten the trap,
trigger down, with the bait about 7 inches (18 cm) above
the horizontal limb. The trap will still work if it is
placed on a horizontal limb, but other species of birds
might accidentally step on the trigger. Other baits may
be used. An unshelled almond is probably less likely to
attract other birds than are the exposed almond or nut
meats. Acceptance of nut baits is not as good when there
is an abundant supply of ripe fruit or nuts available.
Trapping efficiency has
been increased by enlarging the wire bail with a 7-x
9-inch (17.8- x 22.9-cm) piece of 1-inch (2.5-cm) mesh
welded wire. Cut a 1-x 4-inch (2.5- x 10.2-cm) slot out
of the middle of the welded wire to provide clearance
for the trigger release wire and wire it onto the bail.
Also consider using a 4-x 6-inch (10.2- x 15.2-cm) piece
of sheet metal. Cut a “V” out of the sheet metal (for
clearance of the trigger release wire) and fold over 1/2
inch (1.3 cm) of each edge to hold the metal on the
bail. The trigger mechanism can also be enlarged by
attaching a thin round piece (half-dollar size) of wood.
This trap improvement was developed by Bill Clark and
Rocky Loop, of the Tulare County, California, Department
Little success has been
obtained in trapping jays with modified Australian crow
reduce the number of jays present but it is costly and
rather futile as a method of complete crop protection.
Economics of Damage and Control
A 1984 survey of 92
California pistachio growers estimated losses from scrub
jays to be slightly less than $50,000 on 14,263 acres.
This average crop loss to jays amounted to $3.41 per
acre ($8.53/ha). In 1985, an assessment of jay damage in
pistachio orchards in Tulare County, California,
revealed average losses of $150 per acre ($375/ ha).
Pistachio growers may underestimate their losses from
scrub jays because the damage is distributed at low
levels over most of the bearing trees in the orchard.
Figures 1 and 3 were
reproduced from Clark (1986).
Figure 2 was adapted from
Robbins et al (1983) by Clint Chapman, University of
For Additional Information
Beal, F. E. L. 1910. Birds of California in relation to
the fruit industry. Biol. Survey Bull. No. 34. USDep.
Clark, J. P. 1986.
Depredating birds. Pages 701-1 - 726-1 in J. P. Clark,
ed. Vertebrate pest control handbook. Calif. Dep. Food
Crabb, C. A., T. P.
Salmon, and R. E. Marsh. 1986. Bird problems in
California pistachio production. Proc. Vertebr. Pest
Peterson, R. T. 1961. A
field guide to western birds. Houghton Mifflin Co.
Boston. 309 pp.
Robbins, C. S., B. Brunn,
and H. S. Zim. 1983. Birds of North America. Golden
Press. New York. 360 pp.
Scott E. Hygnstrom Robert
M. Timm Gary E. Larson
PREVENTION AND CONTROL OF
WILDLIFE DAMAGE — 1994
Division Institute of Agriculture and Natural Resources
University of Nebraska -Lincoln
United States Department
of Agriculture Animal and Plant Health Inspection
Service Animal Damage Control
Great Plains Agricultural
Council Wildlife Committee