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434 Hand-Rearing Birds

feather damage. Larger terns should be housed in an enclosure at least 10 × 16 × 8 ft. high
(3 × 4.9 × 2.4 m high), but this is not really tall enough to provide practice plunging. Aviary size for
large terns such as Caspian Terns should be at least 8 ft. (2.4 m) wide, 32–50 ft. (9.6–15 m) long and
12–25 ft. (3.6–7.5 m) high. Large gulls can be safely housed in 0.5 in. (1.25 cm) wire mesh “hard-
ware cloth” enclosures. Flooring should be sterilized play sand to a depth of 1 in. (2.5 cm) and the
surface brushed once weekly to remove debris. Wire mesh under the cage may be necessary to
prevent burrowing predator attack. Birds should be held until they are able to make sustained
flights, and in the case of gulls fly up to a perch 6 ft. (1.8 m) above the ground. Terns and gulls
should be capable of sustained flight without panting for several circuits of the flight cage and land
with wings folded.
Terns should walk or plunge into water to capture and swallow live feeder fish of appropriate
size. Gulls should readily eat a variety of foods, including fish, bread, cat or dog food (dry or
soaked), and human “refuse” (fast food leftovers). Gulls and terns reared in groups rarely become
imprinted on humans; however, gulls reared with close human contact may never develop an
appropriate fear of humans and may become a nuisance or a danger to the public.
In the case of Western Gulls and California Least Terns, it is the author’s experience that fledg-
lings of these two species can be safely housed with an adult conspecific in an aviary during the
breeding season. Least Terns tolerate Least Tern chicks in a recovery cage or aviary; Western Gull
adults have sometimes regurgitated food for Western Gull chicks when housed in an aviary. A
recovered adult then can be released with a group of chicks. Some adults appear to welcome par-
enting duties during their own rehabilitation, but others may be stressed by the presence of chicks.
Monitor the situation closely until certain all are doing well.
California Least and Forster’s Terns raised from hatch or brought in for rehabilitation beg for
food from the caregiver and may appear tame. However, once in the fledgling stage when food is
no longer offered by hand, these birds lose their “tameness” and quickly become apprehensive of
human contact if weighed and measured once or twice prior to release.
Chicks of varying ages can be housed together, but older gull chicks may show aggression to
younger, smaller birds. This is manifested in aviaries by the appearance of reddened areas and
missing feathers at the back of the head where they have been pecked. The younger bird should be
separated into a younger group, or the aggressive bird detected and separated from the group.
Adult terns of various species do not seem to attack juvenile conspecifics or other tern species but
do vocalize during competition for food and give warning calls.
Chicks of most tern species remain with the parent and have been observed receiving sup -
plemental food for extended periods of time. Little is known about the survival of hand-reared
birds. However, Western Gull chicks released at 12 weeks of age have been observed surviving
successfully 1 year post-release in San Diego. Banded Caspian Terns that were hand-reared as
chicks at International Bird Rescue in Los Angeles have been re-sighted breeding at Bolsa
Chica Ecological Reserve in Orange County, CA, more than 5 years after release (C. Collins,
pers. comm.).

Criteria­for Release
Birds should be wary of humans, able to sustain flight without panting, bank and turn circles in an
aviary, and land smoothly. The birds’ primary, contour, and tail feathers should be full length, and
the birds should be able to bathe and emerge from the water looking dry (i.e. are waterproof).
Fledglings should achieve the minimum weight for their species, and have no foot or beak abnor-
malities. Birds should readily enter the water to bathe and pick up food.