Tuesday, September 04, 2012

Rainy Day Migrants

Rain during the past two weeks has often kept us trapped within the building at the Audubon Center at Francis Beidler Forest.

Another unfortunate side effect of the rain is the presence of mosquitoes.  As long as there is water flowing in the swamp, mosquitoes are seldom an issue as they prefer standing water.  However, a portion of the boardwalk traverses the high, dry forest and later parallels the edge of the swamp.  The high volume of rain has filled depressions, like those caused when trees tip over, throughout the dry forest bordering the swamp and mosquitoes have taken advantage of the situation.

Even if adult mosquitoes were not present to lay eggs in the standing water, mosquito eggs can survive dry periods and hatch once water returns...cue the rain.  Predators in the water, like mosquito fish or dragonfly nymphs, and predators in the air, like Blue-gray Gnatcachers (Polioptila caerulea) have put a dent in the mosquito population.  However, for a time a bloody gauntlet needed to be endured to reach the sanctuary of the swamp.  The aberrant situation has nearly returned to normal.

We cannot do anything to manage mosquitoes in the forest, but you can manage them in your yard.  Eliminating standing water in any containers is the most effective control.  Mosquitoes obtain viruses during feeding on an infected host and then when next feeding they can introduced the virus to humans and pets via the mosquito's salivary glands. Therefore, if mosquitoes are already present, applying insect repellent and wearing clothing that prevents exposed skin are effective defensive strategies.

Poor weather might slow bird migration, but it will not stop migration.  Even with the rain, we saw birds foraging outside the office window that likely were not residents during the breeding season.  Hooded Warblers (Setophaga citrina), Prothonotary Warblers (Protonotaria citrea), and Worm-eating Warblers (Helmitheros vermivorus) were some examples.  A Green Heron (Butorides virescens) spent a few days wading in the shallow water at #104 just behind the nature center.  Green Herons are not normally seen along the boardwalk, so it may be a bird migrating from higher latitudes or a local bird that could not resist the glut of fish gorging themselves on mosquito larvae in the shallow water.

Another bird seen out the office window is definitely a migrant.  The male American Redstart is black and orange overall, so the bird in the images is likely a female or possibly a juvenile male.

American Redstart - Mark Musselman

American Redstart - Mark Musselman

American Redstart - Mark Musselman

 On Friday, we were able to get out on the boardwalk during a break in the weather.  Two steps out the door we encountered a Blue-winged Warbler, a Worm-eating Warbler, a Black-and-white Warbler, a Northern Parula, two Red-eyed Vireos, a Downy Woodpecker, several Carolina Wrens, and a White-eyed Vireo.  Below, you can see the complete list, including a Veery at #113.

Francis Beidler Forest Audubon Center & Sanctuary, Dorchester, US-SC
Aug 31, 2012 2:00 PM - 4:00 PM
Protocol: Traveling
1.75 mile(s)
Comments:    Clear, 80Fs
25 species

Wood Duck (Aix sponsa)  4
Great Egret (Ardea alba)  2
White Ibis (Eudocimus albus)  27
Red-shouldered Hawk (Buteo lineatus)  1
Yellow-billed Cuckoo (Coccyzus americanus)  5
Barred Owl (Strix varia)  2
Red-bellied Woodpecker (Melanerpes carolinus)  6
Downy Woodpecker (Picoides pubescens)  2
Pileated Woodpecker (Dryocopus pileatus)  3
Acadian Flycatcher (Empidonax virescens)  4
Great Crested Flycatcher (Myiarchus crinitus)  1
White-eyed Vireo (Vireo griseus)  10
Red-eyed Vireo (Vireo olivaceus)  2
American Crow (Corvus brachyrhynchos)  4
Carolina Chickadee (Poecile carolinensis)  8
Tufted Titmouse (Baeolophus bicolor)  6
White-breasted Nuthatch (Sitta carolinensis)  2
Carolina Wren (Thryothorus ludovicianus)  9
Blue-gray Gnatcatcher (Polioptila caerulea)  4
Veery (Catharus fuscescens)  1
Worm-eating Warbler (Helmitheros vermivorum)  1
Blue-winged Warbler (Vermivora cyanoptera)  1
Black-and-white Warbler (Mniotilta varia)  1
Northern Parula (Setophaga americana)  7
Northern Cardinal (Cardinalis cardinalis)  2

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