Posted by ppeery on March 28th, 2010

FIELD SPARROW

Spizella pusilla

The field sparrows, who do winter at Bundoran Farm, have begun singing their lovely plaintive songs to declare their territories.  The song is distinctive: an accelerating series of soft, sweet whistles starting with long duration tones and increasing in rate to a trill.  The male must have an exclusive territory to attract a mate, but territories may be contiguous and only about 2 acres of open grassland.  Thus I hear several singing during a short walk at Bundoran Farm. Click here to hear their song.

The male and the female look alike, are non-streaked with a rusty brown side and crown and two white wing bars.   The pink bill and legs are distinctive.

Nest building begins in mid to late April, with the female selecting the nest site.  The nest is composed almost exclusively of grasses and is located near the ground in early spring, typically near he base of woody vegetation.  The second nest may be in a small sapling.  Since they need open grassland with some growth of short vegetation the field sparrow has been losing habitat and numbers have been declining. The nest may be preyed upon by snakes, small mammals and raptors.  Chipmunks have been observed eating a nestling.   A hot spring day may cause loss of eggs or death of nestlings, but a nest on an eastern slope is less likely to suffer such loss.

The female develops a brood patch and she incubates the 2-4 eggs for 10-17 days depending on the temperature.  The mass of the eggs is approximately 13% of the mass of the female.   Both parents feed the young who are naked when hatched, but are fully feathered by day 8 when they leave the nest.  The parents continue to feed them until they are 26-34 days old.   Like many birds they “outgrow” the nest and leave it before they can fly and feed themselves.

This time of the year the male stays close to the female, so you can usually see both.  They do not flock during the spring and summer, but I have seen small flocks in winter at Bundoran Farm.

 The field sparrow eats small seeds year round, and in breeding season increases the protein content of the diet with adult and larval insects.   They forage on the ground or low-lying vegetation within the breeding territory.  They may perch 3 or 4 meters off the ground to scan for food, pounce then go to another perch.

Dorothy Tompkins – Master Naturalist and Bundoran Farm Steward

Filed under: Education and Inspiration, Nature/Environment