The Norway rat (Rattus norvegicus), the black or roof rat
(Rattus rattus), and eastern gray squirrel (Sciurus
carolinensis) are opportunistic species that will often appear
where there is a reliable source of food and shelter. In urban
areas with hunting restrictions, few predators, and
human-supplied food, their populations often get quite large.

When these species are encountered at a bird feeding station,
I encourage people to stop all feeding until they've developed a
strategy to prevent these resourceful animals from gaining
access to seeds and other food sources.

In addition to the usual recommendation to place an 18-inch
wide metal or heavy plastic guard around feeder poles or
heavy gage wire to keep other animals from gaining access, I
have a couple of other suggestions.

Offer only black sunflower or thistle seed from a tube-type
feeder and reduce the number of feeding ports on the feeder to
only one or two. (I cover all but the lower two ports with
electricians tape.) This allows only one or two birds to feed at
a time which has many benefits, including a large reduction in
seed fall. In addition to the above modification, I've removed all
the perches on my sunflower feeder to prevent it from being
dominated by house finches.

In addition, I strongly advise putting only as much seed in a
feeder as will be eaten in a day. Any spilled seed will be eaten
by ground feeding birds during the day and not rats and mice
at night. If you miss a day don't worry about it, the birds will
do fine.

By providing a specific type of seed in two seed feeders that
have been modified to reduce seed waste, I've been able to
offer a supplemental food source to well over a dozen bird
species without the worry of sustaining a rodent population.

Note that I live in an area where coyotes and owls help keep
rodent populations down. If I were feeding birds in an urban
area where rat and eastern gray squirrel populations were left
unchecked, my feeding strategy would receive even more
careful attention.

Russell Link
Mill Creek, WA