A couple of important bird pests are included here.
The wood-pigeon (Columba palumbus)
Damage: This attractive-looking, 40 cm long, blue-grey pigeon with
white underwing bars is known to horticulturists as a serious pest on
most outdoor edible crops. In spring, seeds and seedlings of crops such
as brassicas, beans and germinating turf may be systematically eaten. In
summer , cereals and clover receive its attention; in autumn, tree fruits
may be taken in large quantities, while in winter, cereals and brassicas
are often seriously attacked, the latter when snowfall prevents the
consumption of other food. The wood-pigeon is invariably attracted to high protein foods such as seeds when they are available.
Life cycle: Wood-pigeons lay several clutches of two eggs per year from
March to September. The August/September clutches show highest
survival. The eggs, laid on a nest of twigs situated deep inside the tree,
hatch after about 18 days, and the young ones remain in the nest for
20–30 days. Predators such as jays and magpies eat many eggs, but
the main population-control factor is the availability of food in winter.
Numbers in the British Isles are boosted a little by migrating Scandinavian
pigeons in April, but the large majority of this species is resident and
Control: The wood-pigeon spends much of its time feeding on wild
plants, and only a small proportion of its time on crops. Control of the
whole population, therefore, seems ethically unsound and is both costly
and impracticable. Physical control involves the protection of particular
fields by means of scaring devices which include scarecrows, bangers
(firecrackers or gas guns), artificial hawks on wires, or rotating orange
and black vanes, all which disturb the pigeons. Changing the type and location of the device every few days helps prevent the pigeons from
becoming indifferent. The use of the shotgun by licenced operators
from hidden positions such as hides and ditches (particularly when
plastic decoy pigeons are placed in the field) is an important additional
method of scaring birds and thus protecting crops.
The bullfinch (Pyrrhula pyrrhula)
This is a strikingly-coloured, 14 cm long bird, characterized by its sturdy
appearance and broad bill. The male has a rose-red breast, blue-grey
back and black headcap. The female has a less striking pink breast and
Damage: From April to September the bird progressively feeds on
seeds of wild plants, e.g. chickweed, buttercup, dock, fat hen and
blackberry. From September to April, the species forms small flocks
that, in addition to feeding on buds and seeds of wild species, e.g.
docks, willow, oak and hawthorn, turn their attention to buds of soft
and top fruit. Gooseberries are attacked from November to January,
apples from February to April and blackcurrants from March to April.
The birds are shy, preferring to forage on the edges of orchards, but
as winter advances they become bolder, moving towards the more
central trees and bushes. The birds nip buds out at the rate of about 30
per minute, eating the central meristem tissues. Leaf, flower and fruit
development may thus be seriously reduced, and since in some plums
and gooseberries there is no regeneration of fruiting points, damage may
be seen several years after attack.
Life cycle: The bullfinch produces a platform nest of twigs in birch or
hazel trees, and between May and September lays two to three clutches
of four to five pale blue eggs, with purple-brown streaks. It can thus
quickly re-establish numbers reduced by lack of food or human attempts
at control. They are mainly resident, only rarely migrating.
Control: Amateur and Professional horticulturists can use fine mesh netting or cotton or synthetic thread draped over trees. Professional horticulturists spray bitter chemicals such as ziram on to shrubs
and trees at the time of expected attack to limit bird numbers. Some
additional control is achieved by catching birds (usually immature
individuals) in specially designed traps, which close when the bird
lands on a perch to eat seeds. Trapped birds are then taken to a nonhorticultural
location. Trapping may be started as early as September.
Large-scale reinvasion by the same birds in the same season is unlikely
as they are territorial, rarely moving more than two miles throughout their lives. Bullfinch trapping is permitted only in scheduled areas of
wide-scale fruit production, e.g. Kent.