Urban Ecology

With Toronto now in the 3rd week of what is shaping up to be a very long
strike by city employees the Toronto Star ran this item on how the uncut
grass in public areas will likely affect the city's wildlife:

Rodents livin' in clover as civic strike brings meadow-like quality to parks
and a feast of trash
Jul 06, 2009 04:30 AM
(41) Leslie Scrivener
FEATURE WRITER
Along the waterfront parkland there's a new sweetness in the air – an
unpredictable bonus in the civic workers' strike.
White clover is growing abundantly, its milky coloured flowers bringing
perfume and a rough beauty to wide swaths of green space. City parks
are looking less manicured and more like meadows.
Nature is having its way with us. And this part, we like.
It's the unpredictable upside to the strike, which has seen precious little
good news, with swimming pools and summer camps closed, and garbage
festering in parks and hockey rinks.
With grass left unattended for the most part, there have been rapid shifts
in urban ecology – biodiversity increases, plants usually mowed down thrive
and go to seed, birds and insects take advantage of the abundance
and – downside! – the rat population is sure to increase.
Tom Nudds, a professor of wildlife biology at the University of Guelph, says
he wouldn't be surprised at an "explosion" of mice and perhaps rats this year,
skunks and raccoons (they usually give birth in the spring) next year. Plenty
of food conveniently located in parks improves their winter survival and future
reproduction. "The strike could be over by the time the lag effect of the food
subsidy – that's what garbage is – kicks in."
The city is slowly being refashioned and naturalized and the urban ecology can
change quickly. "We may move to another aesthetic, an increased appreciation
of the natural setting," says Mart Gross, a professor of conservation biology at
the University of Toronto.
"Plants are food to herbivores and herbivores are food to carnivores. With more
plants and less disturbance there will be more herbivores (insects, rabbits and
seed-eating birds) eating plants, therefore more omnivores (rats, mice and
raccoons) and more carnivores, such as insect-eating birds, skunks and cats
and dogs."
This unintentional greening of the city has multiple effects.
With more milkweed, there are more Monarch butterflies. With longer grass,
moisture is retained in the soil, earthworms thrive – and robins thrive on
earthworms.
Birds such as warblers and vireos feast on insects that are attracted to wildflowers
and weeds.
Mice and voles prefer to nest in tall grass, even grass that's grown an inch or
two longer. Mice attract hawks and owls.
Besides clover, which is valuable because it fixes nitrogen in the soil, we can
see the yellow bird's-foot trefoil and the daisy-like camomile.
Fewer gas lawn mowers at work lead to a reduced carbon footprint for the city
and a more interesting ecosystem, says Stephen Murphy, a restoration ecologist
from the University of Waterloo. "That may be the biggest potential shift and a
potential benefit to the strike."
Orkin PCO, the pest control firm hired to place bait stations for rats at the city's
temporary dump sites, says there's no evidence yet of more rats in the city. (It's
not known how many there are.) But pest control experts and biologists say with
plenty of food in public places, conditions are ideal for the numbers to rise.
Rats will breed more successfully, the babies will be healthier, the females will
store reserves of fat and there will be shorter periods between births. Their survival
rates will go up, though the strike would have to continue for some months to see
this delayed effect.
Rats are enthusiastic breeders. Their gestation period is 22 to 24 days and the
average female can give birth seven times a year. One female Norway (or brown)
rat – the kind we have in Toronto – can produce 60 offspring each year.
In his 2004 book Rats: Observation on the History & Habitat of the City's Most
Unwanted Inhabitants, Brooklyn author Robert Sullivan tells us that rats have
hearty carnal appetites – first sex, then food.
Though their eyesight is poor, they are driven by their sense of smell, which
explains why young children are often bitten on the face by rats attracted by
food residues.
Sullivan reports that male and female rats may have sex 20 times a day. "If
they are not eating, then rats are usually having sex."
An item of interest to Torontonians as the city enters the third week of the
strike: "The only way to get rid of rats is to get rid of the rat food, or
garbage ..." Sullivan writes.
Exterminators are putting out "rodenticides" in tamper-proof stations that are
fastened to a wall or fence. The rodenticides are anti-coagulants, which will kill
the rats four to six days after feeding.
Boris Steipe, a biochemist at the University of Toronto, has been ruefully watching
the fetid pile of garbage at the Christie Pits hockey rink. He knows there are rats
and mice in the area but he's also concerned about leachate. "It contains human
feces, from many diapers, organic waste, a mix of heavy metals, hormones in
medications, whatever gets thrown out." He wants the city to test the material and
fears the spread of toxins, especially since they can become airborne in droplets.
Dr. David McKeown, Toronto's medical officer of health, said Friday that if the site
is managed properly, it should not pose a health risk. "Based on our inspections
so far, I don't see any need to carry out that sort of testing," the Star's City Hall
Bureau reports.
Brady MacLean was walking his dog Pearl south of Lake Shore Blvd. last week and
noticed the longer grass.
He wasn't pleased. It was more difficult to pick up Pearl's droppings and he noticed
some dog owners were leaving droppings where they were deposited. The clover
looked pretty, he said. "Aesthetically, it looks nice."
But he didn't seem convinced.

-------------------------------------------------------------------------

At this point I feel compelled to clarify something. The rats referred to are
a species known as "Norwegian" rats. They are not closely related to your
friend BushRat, whose roots go back to Ireland and Britain. Norwegian rats
tend to be a bunch of troublemakers who give all other rats a bad reputation.
It probably has something to do with their Viking heritage.
Interestingly, the year BushRat was born, a scientist wrote a report on the diet
of the Norwegian rat. Their likes and dislikes are in some ways similar to
BushRat's preferences, although I don't care for oatmeal, and I do like grapefruit.
Here is a piece on the report

RATS LIKE THEIR EGGS SCRAMBLED
A rat's appetite is surprisingly similar to that of your teenage son. Light on raw
vegetables, heavy on rich foods that will make them fat. Martin W. Schein reported
favourite rat foods in a 1953 paper called "A Preliminary Analysis of Garbage as
Food for the Norway rat." He knew from earlier studies that there was a positive
relationship between the number of rats and the amount of garbage. Below are foods
a garbage rat loves and hates to eat, in order of preference:

LOVE

Scrambled eggs
Macaroni and cheese
Cooked corn kernels
Cooked potatoes
Cooked oatmeal

HATE

Raw beets
Peaches
Raw celery
Cooked cauliflower
Grapefruit

Source: Rats – Observations on the History & Habitat of the City's Most
Unwanted Inhabitants by Robert Sullivan

_________________

"The monkeys are throwing stuff at me again."
-Survivorman in Costa Rica