Field Notes

It can’t be long now. A couple of days. Maybe a couple of weeks. But spring is going to break soon.
The snow will melt. The skies will turn blue and the breeze will begin to warm up. The peepers and wood frogs will begin to announce their presence and the first wave of migrating birds will also begin to appear.
Somewhere in that first bird surge, there will be Bluebirds. While some few will winter over here, most have wintered further south and are chomping at the bit to head north. As they head north they will begin shopping for real estate. In fact a pair of Blues just can’t pass up a good bird house.
Bluebirds are cavity nesters and will choose natural cavities like wood pecker holes or rotted fence posts, if possible. But those natural nesting sites are few and far between and competition for those places comes from house sparrows, tree swallows and starlings. Well-built and well placed birdhouses can be much more successful than natural sites.
Bird boxes for blues should be approximately 5” by 5” in the bottom, should be about 8” deep and should have a 1.5” round hole or opening. They should be placed in an area safe from cats and other predators. Backyards are often good places as are golf courses and pasture fields. Bluebirds feed primarily in short grass, posing overhead and hunting like hawks. They will quickly drop down on and grab caterpillars or bugs, then return to their hunting positions.
If you already have birdhouses out from last year, it is a good idea to do some spring cleaning. Remove any old nesting material, then scrape with a flat edge putty knife and brush out the remains with a stiff brush. Washing down the insides with a weak Clorox solution can enhance it further and make it more attractive to future inhabitants.
By the way, last summer’s nest box surveys were above average but down a little from the record summer of 2013. Twenty birdhouses were observed weekly on the observatory grounds. Bluebirds had 10 successful nesting attempts and produced 36 fledglings, down slightly from 12 attempts and 47 young in 2013.
Tree swallows were up a bit and made 11 successful attempts producing 49 young in 2014 compared to 10 attempts and 41 fledglings from the year before. In addition house wrens took over the nest boxes late in the summer and produced several more successful families.
Among the bigger cavity nesters, it was an extraordinary year for the wood ducks that come into the wastewater ponds on the observatory to raise their young. Every year, three or four woodie families show up and usually eight to 10 young will fledge. Young ducks are heavily thinned by crows, hawks, turtles, snakes and foxes, a real killer’s row of predators.
Last summer seven different wood duck hens showed up with families in tow (usually six to 10) along with one family of mallards. With 60 to 70 young ducks going in every direction, the predators did well. But the hens began to work communally in protecting the young and driving off crows. That proved much more successful. So much so that nearly 30 young woodies fledged along with three mallards, probably the best year ever, since I began observing those ponds.
Anyone walking or touring at the observatory would be advised to check out the wastewater ponds. You never know what kind of water fowl you may get to see.
Odds and Ends
Recently some other unusual visitors showed up for a short visit in the neighborhood.
Bob Sheets looked out from his homeplace to see four swans had settled down in the middle of a field. They no doubt were blown in by one of the many snowstorms earlier in the month. They settled in an open meadow to dig around in the snow for something to eat and to rest. Obviously tired from the long flight and disoriented, they rested a few hours with at least one always keeping its head up to watch for danger, then resumed their journey to somewhere.
Dave is a telescope operator at the Green Bank Observatory and can be contacted at davecurry51 @gmail.com.

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