Tuesday, November 5, 2013

Banding Some Marsh Sparrows

Little overnight migration and strong wind gusts created less then ideal conditions for netting birds today. In total, we banded 23 new birds and had 17 recaptures, a sharp decrease from the past few days. We did have multiple previous season recaptures, including a Hermit Thrush and a Song Sparrow from last fall and a Yellow-rumped Warbler that was originally banded in the fall of 2010. 
     The tide was especially high today, so we decided to take advantage by setting up an additional mist net in the marsh. High tides force birds that prefer living in the marsh to concentrate in small patches of habitat that aren't flooded. With a little bit of effort, we managed to flush up and capture 3 species of marsh sparrows. Sparrow species that live in marsh habitat all belong to the genus Ammodramus, and the 3 that we caught are those most expected to be in saltwater marsh areas.

     Seaside Sparrow (Ammodramus maritimus) is the most common, and only year round resident marsh sparrow, on Kiawah Island. It is considered the easiest of the bunch to identify due to its overall gray coloration and large, bulky size. Seaside Sparrows are also notable for their yellow supraloral (area between the eye and bill) patch.

Seaside Sparrow - Note overall gray coloration and yellow lore
     The next two species, Saltmarsh Sparrow (Ammodramus caudacutus) and Neslon's Sparrow (Ammodramus nelsoni) were considered the same species, Sharp-tailed Sparrow, up until 1995. The two can be difficult to differentiate in the field, however there are some key identification characteristics which are easily seen when fortunate enough to study each in the hand.
     Saltmarsh Sparrow is the larger of the two, and is relatively longer billed and has a darker ear covert patch. More objectively observable is the species' pale breast and flanks compared to the orange coloration of the face, along with distinct dark flank streaks.
Saltmarsh Sparrow - Note long bill, dark gray ear covert, pale breast, and dark flank streaks
     Nelson's Sparrow contains 3 subpopulations, which have been previously debated to constitute splits into more species. The costal subspecies, subvirgatus, are very dull and gray in overall coloration. This contrasts with the other two, interior, subspecies, nelsoni and alterus, which have a brighter orange-ish coloration and are much more similar to Saltmarsh Sparrow in appearance. The Neslon's Sparrows that we caught today were both of the alterus subspecies. When comparing a Nelson's Sparrow of either interior race to Saltmarsh Sparrow, it is important to note the smaller bill, dull ear covert patch, and duller, more blurred flank streaking.

Nelson's Sparrow - note duller gray ear covert patch, indistinct flank streaking, and not as long of a bill

     At one point we had the opportunity to photograph Saltmarsh Sparrow and Nelson's Sparrow simultaneously, creating the excellent comparison photo below. More obvious in this photo, but not in the picture above, is the orange coloration of the breast and flank of Nelson's Sparrow, compared to the pale breast of Saltmarsh Sparrow.
Saltmarsh Sparrow (left) and Nelson's Sparrow (right) - note the longer bill of the Saltmarsh Sparrow, and more orangish breast/flank coloration of the Nelson's Sparrow
Ammodramus Sparrow species such as these have a reputation for being difficult to see and challenging to identify. However they are often present in appropriate habitat, and are usually quite responsive to pishing. The birds of this genus are absolutely gorgeous, and worth seeking out by all birders who are willing to spend some time in the marsh!

1 Sharp-shinned Hawk
1 Ruby-crowned Kinglet
5 Gray Catbird
11 Yellow-rumped Warbler (Myrtle)
3 Song Sparrow
2 Swamp Sparrow


1 Eastern Phoebe
1 House Wren

3 Ruby-crowned Kinglet
1 Hermit Thrush
2 Gray Catbird
2 Northern Mockingbird
5 Yellow-rumped Warbler (Myrtle)
1 Northern Cardinal

1 Song Sparrow


# of Birds Banded: 23
# of Recaptures: 17
# of Species: 11
Effort: 93.1 net-hours
Capture Rate: 43.0 birds/100 net-hours
# of Nets: 17 (3 additional nets closed early due to wind)

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