Friday, May 25, 2012

Guest Contribution III By Hemant Kishan

Welcome to this likely last of a series of wildlife contributions by Hemant Kishan as he embarks on composing his own wildlife blog. His blog is certainly anticipated to be on your short list of reading.

A trip to Six Mile Cypress Lake this week astounded me with the water level significantly higher than what had been personally observed recently due to heavy rain storms. The Black-necked Stilts were completely absent as breeding conditions for them changed unfavorably. I'm curious to know where the birds have gone. The species does well with greater latitude at Harns Marsh Preserve although predators of the birds exist there as well. Four Swallow-tailed Kite were observed at a very high altitude at the Lake. A call of owl, not to be mistaken with a dove, was again heard and believed to be that of a Great Horned Owl. Hemant's images presented in this article are seen below . . .

Warblers at Corkscrew -- Part II: Disambiguating the Waterthrushes

Early ornithologists did not distinguish between the Northern and the Louisiana Waterthrush. And, in his seminal work “Birds of North America”, Jean Jacques (aka John James) Audubon called this thrush-like bird the “Aquatic Wood-Wagtail” which is quite descriptive of the habits of the waterthrush: having an affinity for water and compulsively bobbing its tail. However, today, we know that the both species of waterthrush belong to the Wood Warbler family and share the same genus (Parkesia). Earlier, they shared the same genus as the the Ovenbird (seiurus, now monotypic)..

But, enough taxonomic ramblings; more importantly, here’s what these two waterthrushes look like (all photos taken in April 2012 at Corkscrew Swamp Sanctuary, Collier Co.):

In these images, these two species seem superficially the same to the casual observer. However, let’s take a closer look at some of the key distinctions between the two.

The first distinction is the eyestripe and the length of the bill. In the Northern, the eyestripe is buffier and tapers at the end. In the Louisiana, the eyestripe is whiter and of constant width. Also, the bill of the Louisiana is comparatively longer.

The 2nd distinction is perhaps more visually apparent -- the streaking of the Northern is busier and bolder. Also, unlike the Louisiana, the streaking continues all the way up to the chin. The Louisian's throat is always pure white. This is often the first clue that birders look for in a waterthrush.

Finally, the third distinction is in leg color.

As can be seen, the legs of the Louisiana are “buggle gum” pink while those of the Northern are a dull pink. The color distinction is especially obvious in Spring and Summer.

Waterthrushes are regular migrants in Southwest Florida -- especially at Corkscrew Swamp. And, these peculiar warblers afford a good opportunity to test your identification skills in the field.

Please also see Hemant's Finding Vireos at Corkscrew Swamp Sanctuary and Warblers at Corkscrew -- Part I.

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