Saltmarsh Sharp-tailed Sparrow with radio transmitter (left). Overlapping
spatial use by a female (blue) and her fledgling (red) simultaneously
radio-tracked over a 21-day period.
I attach small radio
transmitters (the size of your pinky fingernail) to an adult female and to
one of her nestlings. Some of these nests occur in very large salt marshes
( East River, CT)
and some of them occur in very small marshes (Indian River marsh, Clinton, CT).
Everyday I find the radio-transmittered female and fledgling at the same
time and record their location (using GPS) and the characteristics of the
immediate vegetation. Using spatial statistics I test the relatedness of
the female and fledgling movements as the fledgling gets older and less
dependent on mom for food. By recording fine-scale habitat characteristics
I am able to test if certain plant species or patterns of plant species
influence the movement of both individuals. This is especially important
for the young birds, since they have to push their way through the
vegetation until they can fly.
Sparrows only nest in salt marshes along the eastern US coast.
Salt marshes have the misfortune of occurring where people also enjoy
occurring. Not surprisingly, many of the salt marshes in New
England have been built upon or their tidal dynamics have been
severely altered to the point where the natural salt marsh vegetation
cannot exist anymore. These salt marsh plants are quite sensitive to
changes in salinity, which occurs when the marshes are blocked off from the
tide by roads and culverts.
Sparrows are listed as a Species of Special Concern in Connecticut because of their specialized
habitat requirements and occurrence of this habitat along a narrow strip of
land only along the coast. The males of this species provide absolutely no
parental care. Saltmarsh Sharp-tailed sparrows eat a lot of insects during
the summer and get around the salt marsh by walking and running a lot
through the vegetation. In some Saltmarsh Sharp-tailed Sparrow populations
(like the ones I study) most of the nest failure is caused by high tides
and the subsequent drowning of young in the nest. You could say that these
nestlings are in an evolutionary race to get out of the nest as soon as
possible, and they grow quite fast. They leave the nest 10 days after
hatching, before they can even flutter.