Friday, February 20, 2015

A Mid-Winter Nature Ramble in SW Florida‏

 Can you see the yellow crowned night heron in the top picture?  Look again at the bottom close-up!


Despite the regular procession of cool fronts we continue to enjoy seeing a lot of wildlife and some flowers in SW Florida in early February.  But you may notice that I feature more birds than insects since the cool weather does reduce the sightings of butterflies and dragonflies and other chitinous creatures.  The first willow blooms of the season have been with us for several weeks and always seem early when encountered.  But I need to keep better track of the "phenology" or seasonal timing of blooms.  Are they early this year or not?  It is difficult to remember for sure so some records would be handy.  Put that on the New Years Resolution list !

Sand pine cones_Prairie Shell
We are all familiar with the common slash pines and the less common longleaf pines, but how many of you have seen the sand pine?  It has shorter needles in groups of two.  I have seen it in an area near the Englewood water plant and most recently at the Prairie Shell Preserve.  It is famous for its strange method of reproduction in which the cones remain closed until a fire burns them and releases the seeds. This process is termed serotiny.   Often the tree is consumed in the fire also, so the process resembles that of the mythical Phoenix.  

Long tailed skipper lacking tails in FL yard
An interesting phenomenon is occurring with a butterfly which has no certain answer yet.  Long tailed skippers are being sighted which lack their beautiful tails and the question is why.  I show one example here from my yard.  Are the tails being bitten off by predators?  Are they actually designed to attract predators and thus save the head from attack?  Or is there a genetic variant of the species which simply lacks tails?  Another of nature's many mysteries which invites further observation.

Yellow-throated warbler in FL yard
One of my favorite warblers is the yellow-throated which visits our yard water baths occasionally and feeds in our numerous cabbage palms.  Its coloration is interesting since the male and female are nearly identical and the basic black and white pattern is broken only by a bright yellow throat.  Since sexual recognition cannot be involved with this coloration which does not change during  the breeding season, what is its primary purpose?  Perhaps it is designed to assist with species recognition among the sometimes confusing group of wood warblers?  

Yellow-crowned night heron juvenile
One of our yard birds which undergoes distinct changes in plumage with maturation is the yellow-crowned night heron.  We enjoy seeing these almost daily in our large mangrove trees as they forage for crabs or rest quietly.  The immature herons  are streaked and virtually invisible when motionless in the mangroves.  Only their red iris betrays their presence.  The heavy all dark bill is their hallmark and distinguishes them from the immature black-crowned night heron which has a more slender and partly light colored bill.  The adults have a bold pattern on the head, again likely related to species recognition, but from a distance this also blends in the mangrove background surprisingly well.  

Roseate spoonbill at Lemon Lake
One bird that definitely does not blend into the background is the roseate spoonbill.  It is a treat to see them and as the waters of Lemon Lake fall, spoonbills and other wading birds are attracted to the increasing prey density in this estuarine area. Here again we have a bright coloration which is shared by both male and female.  Perhaps female birds of any species may assume a dull coloration only when they need to be camouflaged when they incubate the eggs?  The spatulate bill of the spoonbill is even more remarkable than its color and seems to be designed by evolution to screen out suitably sized prey of any type from murky waters.  It is one more example of how different bird species divide the prey base among themselves by variation in the method of prey capture.  

Bald eagle juvenile at Lemon Lake
While watching for spoonbills at Lemon Lake a young bald eagle flew overhead and spread fear among the ducks and coots.  It also attracted the attention of an angry osprey which dive-bombed it in an effort to scare it away.  This juvenile or basic one plumage eagle is almost a year old and is changing its feathers over a four year period before achieving the iconic adult coloration.  Why does this huge raptor undergo such a long period of maturation and why does its plumage change so slowly?   Certainly once attaining adult colors the eagle will enter a world of intense competition for nesting sites and food; a gradual process of entering this adult world may reduce intraspecific competition.  So in Florida where golden eagles are extremely rare, sighting of a brownish eagle provides a puzzle for the observer to judge the age of the bird.

Willow in bloom at Amberjack
I suddenly realized that our six months stay in Florida is half over, and the cool winters will soon enough be a memory.   Excitement is beginning to build for the arrival of  the northern spring which is presaged already by a flush of flowers in the pine flatwoods.

Bill Dunson
Englewood, Fl and Galax, VA

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