Week 4 - Day 16 - Bird Pests
ESSENTIAL READING BEFORE COMMENCEMENT OF COURSE:
Urban
Pest Management in Australia: 2004
Edition, UNSW Press, Sydney
by
J Gerozisis and P Hadlington
- Chapter 15 - Pages 193 to 195.
Chapter 15 – Birds - bird problems - common pest species - prevention and control - deterrent methods - trapping - poisoning - shooting
Pest status:
It is an irrefutable fact that the vast majority of birds
provide much pleasure for humans and many play an important
role in the web of life. However, some birds, especially
the introduced species, can be regarded as pests in many
situations and even some native birds are often less than
welcome on certain occasions. The reasons why some
birds can be considered pests are:-
- Defacement Bird droppings frequently deface public
buildings, private dwellings, ledges, windows and footpaths. Inside,
droppings may fall on machinery, tools, structural timbers
and clothing. Accumulated moist droppings may serve
as a medium for fly breeding and development.
- Property Damage Droppings may stop up gutters
and downpipes, causing roofs to leak. Roofing life
can be cut dramatically by prolonged bird usage. The
droppings can be responsible for rust and corrosion and
the uric acid content can mar the paint on automobiles,
machinery and buildings.
- Disease Potential Some virulent diseases can be
spread by pest birds. Some important fungal diseases are
closely linked with bird droppings which serve as a disease
reservoir. The better known diseases include cryptococcosis,
histoplasmosis, Newcastle disease, psittacosis, gastroenteritis,
encephalitis, toxoplasmosis and aspergillosis.
- Associated Pests Certain insects, mites and ticks
capable of affecting the well-being of humans and animals
can be found living on birds or in their nests. Such
pests include: bed bugs, carpet beetles, clothes moths,
cadelle beetles, red poultry mite, tropical fowl mite,
pigeon tick, spider beetle, lesser house fly, larder beetle
and many others.
- Contamination of Food and Feed Pest birds may
not directly consume much food but they are capable of
contaminating vast amounts. Droppings may contain
vast numbers of viable organisms capable of adversely affecting
one's health. Contaminated livestock feed and food
intended for humans must be discarded, thus increasing
costs. Food can also be contaminated by feathers, ectoparasites,
debris from birds' nests and dead birds.
- Depredation of Crops Some pest birds, including
some native species, may cause severe damage to growing
crops such as grapes, apples, cherries, cereals and sunflowers. They
may also feed on garden produce as well as stored grain.
- Noise Starlings in particular can create a considerable
disturbance when roosting together. This exasperating
noise may prevent people from sleeping.
- Safety Hazard Gregarious birds that form large
flocks can become hazardous to aviation. Starlings
and seagulls have been responsible for aircraft crashes.
In addition, accumulations of bird droppings on footpaths,
steps and fire escapes may render them hazardous to pedestrian
traffic.
- Displacement of Native Birds Colourful native
birds are often compelled to leave an area when incapable
of competing against aggressive pest species for food and
nesting sites.
Pest species:
INDIAN or COMMON MYNA Acridotheres
tristis
This bird was introduced into Australia from south-east Asia
in the 1860's and can now be found around Sydney and some
country areas of N.S.W., Melbourne, Adelaide, eastern Queensland
and northern Tasmania. The species is quite common in those
areas.
Habits
The Indian myna is mainly
a scavenger of streets, parks and rubbish dumps and has not
caused any economic harm. However, because of its habit of
living close to man, its presence is more obvious than some
major pest species. In daylight hours, mynas are commonly
seen in scattered pairs or small family groups, feeding on
the ground or perching on elevated sites. At night,
they roost together in groups in dense trees or under cover
such as the underside of a bridge.
Reproduction
The myna constructs a nest made of an untidy cluster of
dried grass, usually in a tree hollow or in thick vegetation. The
breeding season is mainly from October to March. Three
to six pale blue eggs are laid, approximately 30 by 22 mm
in size.
Description
At maturity the birds are approximately
240 mm in length with both sexes being of similar appearance. The head and
neck region is dark brown with a green sheen. The other
upper parts are rich cinnamon - brown, slightly paler on the
underparts. The eye is yellow with a large bare patch
of skin behind and around the eye. The beak and legs
are yellow.
ENGLISH
STARLING Sturnus
vulgaris
The English (or European) starling was introduced into Victoria
in 1861 and later years and was originally a protected species. Since
that time it has become widely distributed in Victoria, Tasmania,
South Australia, New South Wales and parts of Queensland. In
these regions it can be found in cities, towns and open country
areas.
Pest status
The starling is regarded as a pest for several reasons. Its
habit of congregating in large flocks, especially in the
winter months, may lead to serious defacement of buildings
and to deterioration of metal gutters and flashing due to
the acid nature of its droppings. The noise created
by large numbers of these birds can also be a major source
of annoyance. It may attack soft fruits and seedlings
as well as food intended for livestock. The starling
will successfully compete with native birds, excluding them
from an area, and its ectoparasites can make a building unfit
for human habitation until the birds and nest have been removed. It
has also been implicated in the transmission of the disease,
histoplasmosis. On the credit side, the starling does destroy
a wide variety of insects including some known pest species. However,
it is fair to say that its faults outweigh its virtues.
Habits
During the day the birds will forage for food as individuals,
often returning at night to a central roosting area such
as a building or a group of trees. It is very hard
to discourage this practice as they soon become accustomed
to regular noises, traffic and lights.
Reproduction
The breeding season is usually September to January. Two
broods are usually laid, 5 to 7 eggs in each brood. The,
eggs are pale blue to white in colour. The nest is an untidy
assortment of straw and feathers placed in a hole in a tree
or in a crevice in a building.
Description
Juvenile birds are a dull mouse-grey or grey-brown in colour. Adults
have black feathers with green, blue and purple iridescence. The
beak is drab in colour for most of the year but it becomes
bright yellow in the breeding season. The adult bird is 190
to 215 mm in length.
HOUSE SPARROW Passer
domesticus
The house (or English) sparrow was first introduced into
Australia in 1862 and is now widely distributed throughout
urban and country areas of most parts of eastern Australia
including Tasmania. Although small in size, the sparrow can
be a considerable pest in gardens, orchards and around buildings
where it constructs its nest. Sparrows move in flocks
and may drive small native birds out of an area.
Pest status
They sometimes enter houses via chimneys causing concern
to the inhabitants. Their nests are almost invariably
built in or near buildings. These nests, constructed of twigs,
grass, paper or rag, are built in gutters, on roofs,
on building ledges, inside buildings and only occasionally,
in trees and shrubs. Nests constructed around power
lines and in electrical substations can create serious fire
hazards. Their droppings are a source of considerable annoyance.
Large numbers of them can cause serious economic loss when
they feed around poultry establishments and they are also
suspected to be carriers of certain poultry diseases. Experiments
in other countries have led to the conclusion that
sparrows may act as a reservoir for the disease, encephalitis.
Reproduction
The breeding season for sparrows is usually spring and summer
but often occurs at other times. There are usually five or
six eggs, variable in colour but usually greyishwhite
finely spotted grey and brown.
Description
Adult sparrows are 140 to 160 mm long. The male sparrow
has its crown, centre of the nape, rump and tail a light
to medium grey. The back and wings are buffy brown
and the wings have 2 white bars. The throat and adjoining
area of the upper breast are black. The female is a
lighter buffy brown above with a white throat and a dark
streak through the eye region. Both sexes have dark
beaks, brown eyes and buffy brown legs and feet.
PIGEON Columba
livia
The pigeon is by far the most important bird pest in areas
of human habitation and can now be found in most of the world,
particularly in the larger cities. It is not so widespread
in country areas because it is dependent upon man to a great
extent.
Habits
Pigeons commonly eat seeds and grain, other vegetable matter, some fruit, some
animal food such as insects and spiders, some garbage and enough grit to ensure
proper digestion. They consume approximately 500 grams per week. Deliberate
feeding, lack of sanitation and suitable "cliff type" nesting sites
are the main factors that attract pigeons to cities. Pigeons are creatures
of habit and tend to feed, nest and roost in the same places. In city
areas they move in flocks of several hundred, flying and roosting together. Since
they were originally cliff dwellers, they like to roost on high perches such
as window ledges. They will also construct their nests of sticks and
grass in such locations.
Pest status
Although many people are highly tolerant towards pigeons
in public places, they certainly merit their label as the
primary bird pest species. Their droppings deface
buildings, statues and motor vehicles and may also kill
lawns and shrubbery when present in large amounts. Nests
can obstruct drainpipes and gutterings, mar window ledges
and create hazardous footing on fire escapes. Droppings,
feathers and nesting materials may contaminate foodstuffs
such as grain and large quantities of this may be consumed
by pigeons living around grain-handling establishments.
Diseases
Pigeons harbour many diseases some of which are quite virulent. These
diseases may be spread to man, generally through droppings
or via respiratory droplets. Some of the better known
diseases include:-
1) Pigeon
ornithosis - a psittacosis like virus disease causing
only mild symptoms in man;
- Encephalitis - a virus disease which cAn be transmitted
to man from birds via mosquitoes;
- Aspergillosis - a fungus disease of the human ear, sinuses,
lungs or skin.
Ectoparasites
Pigeons also harbour many ectoparasites, some of which cause
discomfort to man or transmit disease. These include
bugs similar to bed bugs, flies, ticks and mites. These
mites, usually the tropical fowl mite or starling mite (Ornithonyssus
bursa) and the red poultry mite (Dermanyssus
gallinae) can be the cause of severe discomfort when
they enter into areas of human habitation.
Reproduction
In addition to the mites, other pests such as carpet beetles,
drugstore beetles, spider beetles, mealworms, dermestids
and flies may all be found in birds' nests. These nests
may be constructed on building ledges, on girders, on roofs,
in guttering, under bridges or on cliffs. There are
1 to 2 white eggs laid in each batch, with several batches
being laid each year. The young birds are fed pre-digested
food ("pigeon milk") which gradually becomes thicker
in consistency until the birds are weaned and ready to leave
the nest.
Description
Pigeons are easily recognised because of their large size
(300 - 350mm in length), stout body, short legs and beak
and smooth, compact plumage. There are many domesticated
varieties with greatly differing colour patterns often in
varying tones of grey. They may live for many years,
commonly living for 15 years and occasionally for 30 years
or more.
Some native birds can also be regarded as pests under certain
circumstances. These include the:-
SILVER GULL or SEA GULL Larus
novaehollandiae
This bird is generally distributed throughout Australia especially
along the coastal areas. It can also be found in New
Caledonia and New Zealand. The bird is abundant the year
round in such areas as harbours, estuaries and coastal rivers. At
certain times it can be found on inland waterways where it
may congregate in large numbers. Its natural food consists
of small fish and other marine life but it will feed on scraps
and garbage. For this reason it can assume pest proportions
where garbage tips are located adjacent to aerodromes. The
presence of large flocks of gulls can prove a hazard to aircraft
and crashes have resulted. For this reason, civil aviation
authorities often take stringent measures in an effort to
discourage birds from the locality.
Reproduction
The breeding season extends from May to February during
which time the birds will nest in a depression in the ground
lined with grass or seaweed. From two to five eggs
are laid. These vary considerably in colour with a
common colour pattern being pale green or brown with umber
or dark olive-brown blotches.
Description
The bird itself is 300 to 350 mm in size white in colour,
with some grey on the wings and red legs and beak.
WELCOME SWALLOW Hirundo
neoxena
The welcome swallow is a well-known bird throughout the
southern regions of Australia including Tasmania. Here
it may be seen in both rural and urban areas, flying low
to catch its staple food of insects or roosting on perches
such as telegraph wires. It is mostly a migratory species
but, in certain areas, birds may remain the whole year.
Under certain conditions it may become a pest by making
its mud and grass nest inside buildings, under eaves or on
verandah posts. The birds' droppings may deface walls
and goods and be of considerable economic consequence. Birds
may return year after year to the same site to raise subsequent
broods during the breeding season of August to December or
occasionally, during the autumn months.
SULPHUR-CRESTED COCKATOO (Cacatua galerita)
and
GALAH (Cacatua roseicapilla)
These two well known members of the Australian parrot family
are notorious among farmers for their attacks upon cereal
crops, especially wheat and oats, pasture grasses and oilseeds
such as sunflower and safflower. on the credit side, they
are kept by many Australian families as interesting family
pets and they may eat large quantities of the seeds of many
weeds.
Originally quite restricted in their distribution, galahs
especially have taken advantage of the increased amount of
arable land to expand their range to most parts of Australia
and are now not an uncommon sight in any part of the country.
The birds' habit of invading oilseed-growing areas has led
to certain localities being abandoned by farmers altogether. In
the state of N.S.W., it is estimated that approximately 20%
of the total grain crop is destroyed each year by cockatoos.
On the domestic scene, sulphur-crested cockatoos may become
pests due to their practice of chewing red cedar window and
doorframes or by destroying small shrubs. They are
most likely to do this when a local food source is no longer
available. In such circumstances, these birds are very
difficult to deter.
permitted chemical controls
The differences in structures, species and problems that
are encountered both between rural and urban areas means
that is a great need for a structured methodology to approaching
the problem of pest bird management. Some forms of control
that may be used are as follows:
- Shooting
- Trapping
- Baiting
- Excluding (IPM)
IPM non-chemical methods
There are many exclusion products available on today’s
market to help solve bird management problems. The most commonly
used of these are bird spikes, stealth netting, bird coil,
bird strand, and many more. In recent times a new product
has been launched called Bird – Shock – Flex – Track.
The track comes in 15.24m rolls in four different colours
and is a very successful product.
bird shooting
This means of control should mainly be used for a single
rogue bird or two, as killing the bird should always be the
last resort for a pest controller. Attempting to solve an
urban bird problem by killing the birds is likely to lead
to many more problems. YOU MUST KNOW WHAT THE LAW IS IN
YOUR STATE, before attempting to carryout control work,
to prevent yourself from being prosecuted and appearing unprofessional.
bird capture
Trapping, as a means of control is widespread. This method
involves encouraging live birds into a trap that is placed
in their roosting or feeding area and that is either baited
with a live bird or, more commonly, with grain. Once a certain
number of birds have been trapped, they are removed and killed.
The traps will then be re-set. Although there is a legal
requirement for the contractor setting traps to inspect their
traps every 24 hours, not all contractors comply with this
legislation and the trapped birds are sometimes left to starve
or die of exposure. It should be noted that if both parents
of a breeding pair of birds are lured into a trap, their
young in the nest will starve to death – as pigeons
breed all-year round there is no ‘safe’ time
to carry out culling operations. This means that decaying
carcasses are left to decompose and become maggot infested
causing far greater health and safety problems for the client
than the original pair of pigeons had caused by their fouling.
chemical controls
Chemical control for birds can and is a very touchy subject,
even if the bird in question is a pest species, the general
public take great concern when they see birds in distress
or dying. Some chemicals that are currently registered for
the control of certain birds are as follows:
Alphachlorose and P
Narcotic Bait (often mistakenly described as poison):
Birds are fed untreated grain in a secluded area for approximately
7 days and on the 8th day the untreated grain is substituted
with treated grain. The grain is treated with a narcotic substance,
the purpose being to induce stupor in the bird so that it is
easily caught and killed. The reality of
these operations is that few birds are actually caught by contractors and a majority
of the birds that have taken the bait fly away to die of starvation, dehydration
or hypothermia. Many birds are found by members of the public flopping about
on the roads and pavements in a distressed state and many are also taken by predators – many
predators (cats, birds of prey etc) will also die having eaten the narcotised
pigeon. Perth City Authority, in Australia, carried out a narcotising operation
in 1999 that went disastrously wrong. The contractor concerned treated grain
with the wrong dose of the narcotic and stupefied birds were seen crashing into
cars and
buses, flying into shop windows and causing mayhem in Perth City Centre. There
was a public outcry as a result. Many town and city councils in the Australia
still regularly use this method of pigeon control, but even this draconian measure
still fails to resolve pigeon-related problems. The dangers inherent in the use
of narcotics are considerable; to say nothing of the fact that many non-target
species (i.e. birds of prey) also take the bait and die a long and agonising
death.
other pest control strategies
Many people do not regard birds as pests. If you fail to
acknowledge this sensitive issue, you could end up with great
hostility and adverse publicity, which could seriously damage
your reputation.
Useful website links:
http://www.ipminstitute.org/school_biblio_buildings.htm#Bird
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