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Gulls and Terns 433

Figure­26.8­ Caspian Terns in an outdoor aviary with a pool. Source: photo courtesy of International Bird
Rescue.

habituated to a human caregiver (Figure 26.8). The caregiver should feed smaller, weaker individu-
als if older birds in the group are more aggressive. Older juvenile terns are less likely to attack
younger birds housed with them than are gulls. Overcrowding (or simply aggressive personalities)
can cause Western Gull chicks to peck at the heads of younger birds and cause feather loss and
sometimes lacerations.

Encouraging­Foraging­Skills
Western Gulls feed on land and water, but do not usually dive for food. These birds require no par-
ticular training to pick up food. For terns, first place the usual food dishes in the aviary near the
pool. After a few days, place the fish at the edge of the sloping pool. The pool should be about 4 ft.
(1.2 m) in diameter and 1 ft. (30 cm) deep in the center so that the birds are used to picking up fish
in the shallow area. Then toss the fish in a little deeper, and encourage the birds to wade into the
water. Terns will not jump into deep water, so the slope needs to be gradual. If birds are reluctant,
feed at 8:00 a.m., and then withhold food until 3–4:00 p.m. After several more days the fish can be
placed somewhat deeper, and the birds should wade and then fly in and pick them up. Finally,
feeder (live) goldfish should be placed in the food dishes for a day or two so the birds are accus-
tomed to catch the feeders, and then the live feeders placed in the pool itself. Sometimes the birds
have to be left with the feeder fish all day before they will forage, but hunger will usually prove
adequate to overcome the reluctance to enter the water.

­ Preparation­for Wild­Release

Pre-release conditioning aviaries for small terns should minimally be 10 × 12 × 8 ft. high
(3 × 3.6 × 2.4 m high) with predator proof plastic mesh netting (0.25 in./0.5 cm mesh) to prevent