Unusual Sparrow Recapture - Brian Johnson

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Last week Ric Pedler mentioned that he saw a banded Grasshopper Sparrow along Seba Road near the pine plantation on the south Wastewater properties. This location is a little outside my designated study area and has hosted few Grasshopper Sparrows in the past. However, the destruction of the nearby fields has substantially reduced the densities and nesting success of most grassland species. Since some birds still remain in small, peripheral patches, I have been curious whether they are individuals that have emigrated from territories which offered suitable habitat in the past or whether they are young birds colonizing usable, albeit deficient, grassland. If the latter is true, then there is a strong likelihood of very high mortality among the birds from the treated grasslands.

Today, I netted Ric's bird. The band on the right leg (1601-95246) indicated I had banded it last year. When I entered data, I referred the band against the original capture. Amazingly, I had banded this bird on August 13 as a nestling! It was one of three chicks from the last nest I found in 2009. Considering how late it was in the season, I was pessimistic that these birds would ultimately survive. While one of its siblings (#247) was captured on September 2, 243 meters west of the nest, it had not yet initiated its preformative molt (which is very tardy) and meant that it would either have to migrate south in juvenal plumage (which is extremely unusual) or try to finish its molt while constrained by a increasing dearth of food resources.

Apparently captured near the center of its territory, bird #246 has moved only 504 meters from its natal site. Little data exists on dispersal patterns of grassland birds, so I don't yet know how it accords with such movements, but I find it fascinating regardless.

- Brian Johnson
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