[va-bird] Re: Nest boxes- a cautionary tale

Bill, 
I had a bad time with snakes until I started making ruffled skirts made of 1" 
garden netting to put around my metal poles. (this also works with trees) Mr. 
Snake will get all tangled in the netting. If we see the trapped snake in time, 
we take the whole netting off the pole and drive a few miles up the road and 
painstakingly cut the netting off the snake and set it free. The snakes are 
very patient and allow us to do it. Of course I am in charge of the head,  
which I keep down with a forked stick. I hate snakes, but can't let them suffer 
(unless it's a Copperhead)
It always amazes me to see the bluebirds coming and going tending to the 
nestlings even with a snake trapped a foot below the nest box. They seem to 
understand the the snake can't harm them. Jays and such will dive at a trapped 
snake and they make the Bluebirds more nervous than the snake.
So far, since we have started doing this, we've not lost any nestlings in our 
boxes to snakes, we also add an extra piece of thick wood to the hole, making 
it too deep for raccoon  and possum predation.
It can get discouraging, but Bluebirds are persistant,as you mentioned .
So far we've had 15 fledglings, and all boxes are holding eggs again, so 
expecting another 15 (we hope) making a total of 30 Bluebird fledglings from 
our 3 nest boxes.
The Wal-Mart boxes are very good, if you modify the hole.
Take Care..
Lynda Blair
New Kent, VA
  ----- Original Message ----- 
  From: wdunson@xxxxxxxxxxx 
  To: va-bird@xxxxxxxxxxxxx 
  Cc: bristol-birds@xxxxxxxxxxxxx 
  Sent: Monday, June 26, 2006 3:59 PM
  Subject: [va-bird] Nest boxes- a cautionary tale


  When I made preparations to put up a large number of bird nest boxes for the 
season on our 45 acres of pasture and fence rows, I made an assumption that 
predation would not be a major factor.  This assumption goes against the advice 
of various groups that deal with blue bird boxes but their anti-predator 
designs require a considerable extra effort and expense compared to simply 
buying a box and screwing it to a fence post, tree or garage.  Also I had never 
actually observed any nest predation.  So I put up 40 boxes without predator 
baffles or guards.  The results in to date indicate that predation is in fact a 
major obstacle to bird reproduction in boxes.  At least that is my conclusion 
from the results below:
  (note that documentation of the entire phases of nesting is not completely 
adequate so there is uncertainty about many details)

  1.  40 boxes were installed without baffles or guards

  2.  33 boxes were used to the extent that nests were built by tree swallows, 
bluebirds or house wrens

  3.   18 nests had documented eggs and/or nestlings

  4.   7 nests probably fledged young (2 bluebirds, 5 tree swallows)

  5.   Predation was directly observed in one TS nest by a black rat snake and 
indirectly surmised in many others by the presence of nesting material pulled 
out of the entrance hole (by racoons probably), and by the sudden disappearance 
of nest contents

  I concluded that a lot of predation occurs (clutches that disappear) and that 
baffles could only help.  I am switching entitrely to a system recommended by 
the VA Bluebird Society whereby the box is mounted on a galvanized metal pole 
with a sheet metal baffle underneath.  This is simpler to build than some other 
similar systems:

  http://www.virginiabluebirds.org/pdf/guards_2.pdf

  I also highly recommend the inexpensive cedar nest boxes sold by Wal-Mart 
(and built in Ohio!) that have a front-opening door that greatly facilitates 
checking the nest contents.  I have discarded all my old booxes that do not 
provide easy access for examining the nest.  Without this technique I would 
have remained unaware of the predation that was occurring.

  I doubt that we have an unusually large number of predators here (foxes, 
possums, racoons, rat snakes, coyotes, etc.) and I do exercise a higher degree 
of predator control than some might in more civilized surroundings.  Thus I am 
quite surprised that birds nesting in boxes have such a tough time in avoiding 
predation.  Those birds that nest in our yard under more natural circumstances 
(carolina wrens, brown thrashers, mockingbirds, cardinals, song sparrows, etc.) 
seem to have been successful in bringing off fledgings.  So perhaps the 
unatural conditions of nest boxes ,especially when arranged along fence 
hedgerows, focus the attention of predators on nesting birds (snack paks for 
snakes?).  The other thing I have learned from this experience is that 
bluebirds and tree swallows are incredibly persistent in re-nesting after 
repeated losses of their eggs or babies.

  Bill Dunson
  Galax, VA

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