Thursday, October 24, 2013

A Blast of a Dove Season!

Temperatures dipped into the 40s°F today, prompting additional layers for the crew. When experiencing lower temperatures, we take additional precaution with the birds to help prevent ‘cold stress’. Most species that are prone to cold stress are smaller in body size such as kinglets, gnatcatchers, and some warblers. We band these species first, and even transport them inside our jackets to help keep them warm. A whole new meaning to having a down jacket!

Cool air temperatures don’t put migration on hold; we banded 91 new birds today by the time it’d warmed to the low 60s°F when we finished for the day. Of the 18 unique species we handled today, a pair belonging to the same species was a delightful surprise.

While the Mourning Dove is abundant across the United States, it is an uncommon capture at our station; the pair banded today brings our total to three for the season thus far. Their larger size and powerful wings in conjunction with the smaller mesh size of our nets (designed for smaller passerines) make it difficult for the dove to become entangled at first contact and have proven easy for escape once in the net. As luck would have it, two crew members were in the right place at the right time and were able to ensure the safe and effective capture of these two beautiful birds:

Mourning Doves 
(AHY female pictured left, and HY male pictured right)

In addition to being a cool capture, these birds provided an excellent chance to compare both juvenile and adult plumages. Below you can observe both the after hatch year (bottom) and hatch year (top) wing. A characteristic that immediately identifies a hatch year wing is the presence of buffy tips on one or more feathers. Our hatch year bird presents many buffy tipped feathers while the after hatch year below has none. Additional clues that identify a bird as a hatch year include the presence of molt limits [the contrast between new (replaced) and old (unreplaced) feathers] amongst the primary feathers. In our hatch year dove, you can see a clean contrast between the older juvenile feathers, which are worn and brown (left of the arrow), and that of the new adult feathers, which appear fresh and gray (right of the arrow). In comparison the adult wing exhibits uniform gray feathers; molt limits can be found in adult wings but the color will be uniform.

Aging Comparison of Mourning Doves Using Wings
(AHY pictured bottom left, HY pictured top right)

- Claire

2 Mourning Dove
1 Yellow-billed Cuckoo
5 Eastern Phoebe
1 Blue-headed Vireo
6 House Wren
2 Golden-crowned Kinglet
4 Ruby-crowned Kinglet
1 Hermit Thrush
25 Gray Catbird
1 Northern Mockingbird
19 Yellow-rumped Warbler (Myrtle)
6 Palm Warbler (Western)
6 Common Yellowthroat
1 Northern Waterthrush
1 Painted Bunting
1 Northern Cardinal
1 Song Sparrow
8 Swamp Sparrow

1 House Wren
1 Ruby-crowned Kinglet
9 Gray Catbird
1 Northern Mockingbird
2 Northern Cardinal

# of Birds Banded:  91
# of Recaptures:  14
# of Recaptures:  18
Effort:  103.5 net-hours
Capture Rate:  101.4 birds/100 net-hours
# of Nets:  20

No comments:

Post a Comment