How I Came to Understand Bird-Friendly Must Be Bird Safe

In my bird club and my community I have been working very hard to increase native plants in residential landscapes. I pleaded, “only if we get above 70% native vegetation, will add 2 net nestlings per nest of the birds we love to watch and feed.  Plant native and keep those nestlings alive.”  Forty-five per cent of our bird club report planting natives.  (See for this innovative program.)

At the same time, I have also worked very hard to prevent bird window strike deaths. Even with and average of just two (2) (or three) bird deaths per residence from window strikes annually, the loss of birds is staggering – hundreds of millions. I urged club members and neighbors to prevent the annual “two deaths per residence” from window strikes.

+ 2 more nestlings -2 bird collision deaths =0

I was struck by the simple artihmetic.

Two more birds per nest if we increase native vegetation.

Two less birds every year per home from bird window strikes.

Two more, two less = zero gain.

Of course, in a typical suburban neighborhood, there are more than chickadees nesting.  Hopefully the cardinals, mockingbirds, wrens, finches and song sparrows will also produce two more young per nest.  Thus there will be 10 more nestlings. Assume also that they all have a second successful brood. But there is a catch. The feeding range of chickadees is about 80,000 square feet.  For the sake of discussion, assume that the feeding range of those other species is about the same.  A typical tract home lot is about 10,000 square feet. Thus there will be eight homes in that range, four times more glass and 20 deaths from window strikes and over 60 cat related deaths.  See spreadsheet below.

Exact arithmetic computations are not possible when working from general mortality estimates (2 deaths per residence) to actual breeding ranges. They are illustrative.  However, the overall conclusion is clear – if bird friendly yard programs do not start by preventing window strike deaths, the native plantings in those yards may result in little or no increase in bird population – the goal of bird friendly yards.

Yes, birds can have more than one brood – but it is also true that if one of the parents dies from a window strike during the feeding period, that the entire nest will fail.

When you add cat mortality – about 60 more deaths –it is clear without question that the yard must be safe.

The Following Spreadsheet Shows Why Not Net Gain if Yard Unsafe And includes citations.

Published by ornithologycenter

I am dedicated to helping birds. I concentrate on making sure they have enough to eat -- and thus promote native plants, and making sure our yards are safe for them -- and thus promote the use of systems to protect birds against deadly window strikes. I worked for national environmental organizations, in the U. S Senate as Chief Counsel of the Senate Agriculture Committee and as a policy adviser in a presidential campaign.

Leave a Reply

%d bloggers like this: