A Bounty of Bluebirds

Bluebirds  RE-6

Male Eastern Bluebird (click to enlarge)

A friend posted a picture yesterday of bluebirds in her nest box. So I went out this morning and checked the one box I have that can be easily opened, and it looks like a good bluebird spring! The male and female were watching me as I went over to the box and opened it so I didn’t stay long and just took a shot with the iPhone instead of the usual gear, but it is always exciting to see the first babies of spring. These guys look like they are just a couple of days old at most and still in that reptilian stage of development. I am sure the cool, wet weather the past few days has made for difficult hunting for the parents but the sunshine today promises easier meals for these young.

Bluebird nestlings

Bluebird nestlings (click to enlarge)

I have four nest boxes scattered around the yard and garden area (three out in the open and one in the woods) and have seen bluebirds coming and going from all four, so this could be a very good spring for bluebirds. Looking forward to following the progress of these and the other local breeders during the coming nesting season.

How readily the bluebirds become our friends and neighbors when we offer them suitable nesting retreats!
– John Burroughs,1925

Bluebird houses

Bluebird nest box

Bluebird houses

Nest box

Bluebird nest box made with hollow log

Nest box

Bluebird houses

Nest box

Wood Duck nest

Waterfowl wayside

Wood Ducks pairing up in winter (click to enlarge)

Wood Ducks begin courtship in the fall and continue throughout the winter and into the spring. A couple of years ago I photographed several ducks on the ice at Pungo Lake where you can see several Wood Ducks that appear to have already paired up. On my recent paddle at Merchants Millpond and surrounding swamps, I flushed several male wood ducks that were probably tending to their mate as she sat in a nearby nest cavity – a fact supported by the occasional flush of a female from a cavity. The male remains near the nesting female until the eggs are within a few days of hatching, which is longer than males of most other duck species remain with their mates.

Wood Duck nest boxes

Wood Duck nest boxes

Although swamps are great places for cavity nesting birds due to the abundance of hollow trees and cavities, I often see artificial Wood Duck nest boxes placed along these waterways. This pair of boxes is along Bennett’s Creek and the one facing the creek had a fluff of down clinging to the entrance hole, indicating it might be occupied. Naturally, I wanted a peek…the box builder had done a good job so the side door easily opened and this is what the camera caught inside…

Wood Duck eggs in nest box

Wood Duck eggs in nest box

Like most (if not all?) birds, Wood Duck females lay one egg per day until she finishes and begins incubating. Normal clutch size according to many sources ranges from 6-16 eggs with an average of 12. So, how many eggs do you see in this nest? Certainly way above the average number for a clutch. This may be an example of intraspecific brood parasitism, also called “egg dumping” or “dump nesting”. Egg dumping occurs when a female wood duck, frequently a first-year breeder (according to some references), follows another hen to a nest site during the egg-laying period and lays her eggs in with the other nest, presumably coming back each day while the original female is away foraging to keep laying until she has finished. This results in very large clutches that often cannot be effectively incubated. In a typical nest box, approximately 80% of the eggs hatch, but where egg dumping is common, it may drop to as low as 10% or the original female may abandon the nest altogether. Some suggest that in the wild, the impulse to egg dump is kept in check because wood ducks normally nest in fairly isolated locations. Artificial nest boxes that are placed too close together or in very conspicuous locations may lead to increased egg dumping (some reports are as high as half the nests). Several resources recommend trying to mimic the natural situation (single boxes placed in swamp habitats) as much as possible to help with nest success.

Rat snake in wood duck box

Rat snake in wood duck box (click to enlarge)

The other thing people recommend is placing the nest box on a pole with a metal predator guard to help reduce predation from raccoons. But there are other species of predators that the ducks need to worry about as I once observed while paddling on the Scuppernong – a nest box with a guard had been placed a little too close to a small overhanging tree limb…

If all goes well, after about 30 days of incubation the eggs hatch (usually in April in these parts). The tiny fluff balls may stay in the nest for several hours until coaxed out by the hen. If the nest is in a tall tree and away from water the ducklings take a dive out of the box and literally bounce on the ground before heading off in a line following Mom to the nearest waterway.

Check out this site for live views (and recordings) of the inside of a nest box here in NC – http://woodiecam1.com/.

Hollow Log Bluebird House

Bluebird nest box made with hollow log Bluebird nest box made with hollow log

This is in response to a friend’s request for information on a natural-looking bluebird house. I have made several of these out of appropriate sized hollow tree trunks (just compare to a commercial bird house for approximate dimensions). After finding and cutting the hollow log into reasonable lengths, I use a large screwdriver to scrape out the interior (if needed) so as to have a decent cavity. The entrance hole is made with a one-inch diameter drill bit. I usually rough up the edges a bit to enlarge it slightly and to make it look more natural. The top and bottom of the house are made with rough lumber. I pre-drill and attach with wood screws. The roof has an overlap all the way around to provide some shelter from rain.

The mounting bracket is made with a one-inch strip of aluminum (Lowes, etc. carry all of these pieces) cut to a length that allows it to be doubled over for inserting into the mounting pole. Drill two holes for the bracket to attach it to the back of the house. I am careful to use the shortest possible wood screws so there is not a sharp screw tip inside the nest cavity that might injure the birds. Then bend the bracket so the free end slides down into the mounting pole. I usually compress the top of the mounting pole with a hammer so the bracket slides easily down into the narrow slit. One and a quarter-inch diameter electrical conduit is used for the long top mounting pole (I usually use 10 ft lengths and cut them in half). It then slides over a shorter, smaller diameter rod or piece of re-bar driven into the ground with a sledgehammer. Strike the conduit with a hammer a foot or so from the bottom to create a dent that will act as a stop when it hits the top of the ground pole as you slide the conduit down over it. The location of the dent allows you to adjust the height of the unit as needed. The boxes tend to last a few years depending on the durability of the hollow log. I rarely clean out these boxes but they are used many times (after all, no one is cleaning out the natural cavities out there and some studies of nest boxes have hinted that parasites of nest parasites increase in number, thereby reducing nest parasite populations, if next boxes are not cleaned out frequently). Before setting in the box, I often finish the pole system off by slipping a length of 4 inch diameter PVC pipe over the mounting poles. Some say this may help deter snakes from climbing into the nest box. If I use it I always put sticks or grass or other debris down into the top of the PVC to prevent any birds from getting stuck in that pipe.

All of this effort is to provide a natural-looking cavity for the birds and a photographic backdrop for me. I usually put a pop-up blind near the nest box and allow the birds to acclimate to it empty before I start entering and taking pictures. Below are a couple of images from one such nest box in late afternoon light.

Bluebird at log nest box Bluebird at log nest box