Woodpeckers
There
are more than 10 different species of woodpeckers
(Sphyradicus spp., Dendrocopus spp., Asyndesmus
spp., Colaptes spp., Melanerpes spp., Picoides spp.,
Dryocopus spp.) in North America. They thrive
in the suburban environment where trees are intermixed
with houses. Their main diet consists of wood dwelling
larvae and insects that often prefer dead wood. Dead
wood is also the preferred material when they excavate
their nest holes. Dead wood is what we build our houses
from so to the woodpeckers our houses are considered
to be “super trees”.
| Woodpeckers
usually excavate a new nest site each year.
Old nest sites are often inhabited by other
species such as owls, nuthatches, chickadees
etc. The nest is lined with wood chips from
their chiselling. Most houses do not cater for
nesting as the wooden walls are to thin for
a nest site.
However,
numerous holes can often be found in the walls
of a house. These are either holes which have
been excavated in the process of catching insects
and larvae or evidence of woodpeckers using
the house to as a “drum”. Woodpeckers
“drum” on wood in order to attract
mates and as a territorial signal. This drumming
can also be made on metal surfaces such as drain
sprouts, streetlights, TV antennas, silos or
anything else that resonates loudly.
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The most famous incident happened when a pair of woodpeckers
drilled almost 200 holes into the foam insulation
of the space shuttle Discovery's external tank, causing
it to be rolled back from the launch pad for repairs.
Besides direct damage to walls of houses the noise
itself can be very annoying. The drumming often begins
in the early morning and can be so loud inside the
house that it is very disturbing. As the drumming
is related to mating the worst period of the year
is in the spring.
Crows
During
the last three decades large numbers of crows (Corvus
brachyrhynchos) throughout North America have
chosen to change habitat from rural to urban. Large
noisy roosts can be seen and heard in most cities
across the country through the winter. They are very
social and intelligent birds that are able to take
advantage of the opportunities the urban environment
offers.
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As
natural scavengers they readily feed on
urban scrap such as French fries, bread
and hamburgers that they pick from dumpsters.
A unique behaviour is the savaging for fat
covered gravels and pebbles located around
roof top restaurant ventilation systems.
Additionally they find good nesting spots
in the open, tree-filled landscapes that
dominate urban areas. They typically build
nests 5 to 20 m off the ground in trees.
They
build their nests of sticks and twigs lining
it with shredded bark, grass or similar
materials. Crows have a more social family
life than most other bird species. Often
offspring from previous years stay near
their parents and help raising the next
fledglings. In the northern parts of the
country crows are migratory and will fly
south in winter but in the coastal, southern
regions they will stay throughout the winter.
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Crows are regarded as an agricultural pest bird due
to their diet of corn and other farm crops, but are
a minor urban pest compared to gulls, pigeons, starlings
and house sparrows. It is mostly their dumpster related
eating habits that annoys people as they are capable
of making quite a mess while searching for edible
scraps. During the nesting season when the fledglings
are unable to leave the nest the parent birds are
very protective of their young. Any person or animal
that come close risks an attack by the parent birds.
Their big noisy winter roosts can also attract negative
attention and their droppings can smear cars and buildings
and pose a health risk. Crows are the primary bird
species that harbours the West Nile Virus, which they
pass along to mosquitoes. When mosquitoes successively
suck blood from crows and humans the disease can be
transferred from bird to human.
Geese
Canada
geese (Branta canadensis) have substantially
increased in numbers through the last decades in urban
areas. The increased numbers of parks, gardens, airports,
recreation fields, business parks and golf courses
have provided the species with near perfect habitats:
well-kept irrigated lawns dotted with numerous ponds
and small lakes with few predators.
| Geese
are herbivores and graze on the well-kept
lawns in the urban environment. The numerous
small freshwater bodies also provide the birds
with good nesting sites. The nest is build
near water preferably on small, secluded islands
or rocks in order to protect them from land-based
predators.
Geese are very territorial and will defend
their nest against all living creatures including
humans and their pets. They are big birds
and deliver a fierce ”bite”. Since
they are a protected species the modern urban
geese display no fear of humans. The Canada
Goose has increasingly developed into a pest
bird as a result of their steadily rising
numbers. Faeces and feathers create a mess
of the lawns they occupy to the great annoyance
for gardeners and property owners. |
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The faeces can over-fertilise the lawns and contribute
to excessive algae growth in ponds and lakes which
leads to oxygen depletion and the death of fish. Water
reservoirs used for drinking water can also be polluted.
Golf greens get rough and uneven when geese feed on
them. The modern urban geese are non-migratory and
once they have established themselves in an area they
prefer feeding at the nesting site, but will often
fly long distances to and from favourite feeding grounds.
Near airports geese pose a severe hazard to air planes
due to their size and their flocking behaviour. An
increasing number of aircraft strikes have been observed
and they often result in emergency landings, costly
repairs and sometimes crashes.
Starlings
Starlings (Sturnus vulgaris) were introduced
from Europe in 1890 in Central Park in New York. The
100 starlings have since spread slowly across all
of North America with the exception of the far north
and multiplied into more than 200 million. They reached
the west coast only a few decades ago. They feed mainly
on berries and insects but also on invertebrates,
fruits, grains, seeds and garbage. They form big roost
twice a year: in summer after nesting has been completed
and in winter where the biggest roosts are formed
sometimes counting more than a million individuals.
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Starlings
are cavity nesters and the urban environment
provides the birds with abundant nesting
sites. They compete with other cavity nesters
and the starling is fearless and aggressive.
They sometimes watch other birds build a
nest before forcing them to leave and hereby
save themselves the work to gather nesting
material.
Nests are
made with different kinds of materials including
grasses, twigs, feathers, and even trash,
and are built in cavities often in trees,
birdhouses and in buildings such as air
vents. The urban starling is not migratory,
but may move from rural areas to warm city
buildings in winter.
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When large numbers (up to tens of thousands) gather
for night roosting in urban areas they pose a nuisance
to many homeowners as they overwhelm buildings and
trees. The noise, odour and extensive defecation caused
by these congregations can be horrendous. The uric
acid in the faeces can corrode stone, metal and masonry
and may damage trees. Fungi nurtured in the dried
guano often results in Histoplasmosis infections in
humans and bacteria and parasites also pose a health
risk. The habit of nesting in cavities can pose fire
hazards as the nesting material is very flammable
and often is placed right on top or next to electrical
installations.
Swallows
Cliff & Barn Swallows
(Hirundo pyrrhonota, Hirundo rustica) readily
nest in urban areas where they place their mud pellet
nests in man made structures. These structures provide
the shelter that their mud pellet nests need. As their
diet exclusively consists of insects the attraction
to the urban environment is based on the availability
of nest sites.
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swallows now face strong competition from
the introduced House Sparrows for food and
shelter and this may be why their numbers
are falling. Due to the use of mud pellets
as building material for their nests swallows
prefer to nest in close proximity to freshwater
sources such as rivers and lakes. Swallows
live in colonies ranging from a few pairs
to several thousands.
The nests
resemble a rounded wine bottle or carafe with
the opening on the side. Inside the nest is
made soft and comfortable with feathers and
grass. In the spring when the swallows return
from their winter refuge in South America
the same pair will repair and reuse the same
nest they used the year before.
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Swallows are mainly considered a pest bird due to
their nesting habits. The mud nests can damage the
outer walls and eaves of buildings. The wall and ground
beneath can often be covered with feces. Especially
where livestock is living underneath nesting swallows
issues of salmonella infections are of concern. Parasites
from the nests can also enter buildings through cracks
and crevasses and pose a health risk to humans.
Tree
Swallows are now presenting themselves as an urban
pest bird in their recent adaptation to nesting in
the rain screen systems used in contemporary buildings
in the Pacific Northwest. The improper attention to
building design in a region inhabited by Tree Swallows
can lead to a pest bird infestation capable of plugging
up the airflow screens and vents.
CLICK
HERE FOR A VIDEO PRESENTATION ON SWALLOWS
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