[CT Birds] questions on Bluebird boxes.

Carrier Graphics carriergraphics at sbcglobal.net
Fri Jul 23 12:03:59 EDT 2010

I was recently asked about this subject  - So for those who might be interested 
in FACTS pertaining to bird boxes and esp Bluebirds, here they are from several 
sources, plus some from my 30 years of maintaining  Bluebird box trails of up to 
200 boxes. 

Usually two broods a year here in CT.

1st week, female will leave eggs for a day while incubating.

2nd week, she will leave for no more than 1 hr or the eggs might chill.

Female sleeps on eggs for one week or more after hatching.

Brooding temp is 95-98 degrees. over 107 will kill them. 

It takes 13-14 day to hatch, unless cold, then up to 21 days.

Day of hatching, baby's weigh 1 oz. 3 days 2 oz.

Day 11, babies very active in box, Day 14, peer out of opening.

18 days after hatching, they fledge. If food abundant, 1 day earlier.

Adults catch prey every 2 of 3 attempts. Can spot prey 75 feet away.

One week after fledging, parents supply food, Female then builds new nest.
Male still guards - feeds young.

2 weeks, fledglings feed on their own and become self sufficient.

1st brood, average 75-95% successful. 2nd brood about 55%. (first broods here in 
CT much lower than average because of cold, wet April weather).

Most young Bluebirds die within their first year. 50% survival is above average.

One in ten young reach adulthood. Up to 50 % adults die each year. 
Average age of a Bluebird in wild is only 2 years. 

Best placement of BB box. Morning sun good, afternoon, some shade good. 

Best positioning. Hole facing south best - Also south east or south west OK. Not 

Always use a predator guard on box pole. Without, your chances of having a 
failure are over 50%!
Ground predators to boxes on un protected poles are: cats, raccoons, mice, 
bears, snakes (Black rat snake, Black racer, poss Milksnake here in CT). A cheap 
guard is a 3 foot length of PVC pipe.

Two boxes placed 20 feet apart is best luck for attracting Bluebirds. One for 
them, one for another species. They will nest side by side without interfering 
with each other. (cept for House Sparrows, the worst detriment to nesting birds 
in boxes).

Always make sure your boxes are in good shape! if not, they become death traps 
to the birds using them! They should always be water proof. If un treated, the 
wood will crack in time. Replace the part, or make a new box. 

Never paint a box inside! Also-boxes do best if not painted. Wood needs to 
breath, so weatherproof the outside with stain or other clear penetrating 
solution. Best is a mixture of diluted linseed oil with or without stain. You 
can put on new coats of this throughout the years. 

Roof. A wood roof should always be protected with something. My best luck has 
been the following.....

Cut a roofing tile to fit with half inch overhang all around. I then coat the 
wood roof with roofing tar, position the tile, then use 4 small, short brad 
nails to secure. I have had boxes last 20 plus years with this type of roof. 

Good luck, and remember. It is our responsibility to give the birds a better 
chance of fledging their young than they would have in the wild. By using a 
built bird box that is in good shape and protected with a predator guard, the 
chances of successfullyfledging are roughly 40 to 75 % depending on the years 
weather. In the wild, it could be much less.

Paul Carrier

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