Sunday, December 27, 2015

Nature's Holiday Gifts‏

Mangrove skipper
Mother Nature has given us some beautiful gifts this holiday season in conjunction with unusually warm weather.  The insect world has been especially active.  
Mating Dorantes skippers
This spectacular mangrove skipper was attracted to a Mexican mallow in our yard.  A pair of Dorantes skippers was found in love near Arcadia.  The long "tails" of this relatively recent arrival in Florida may be of benefit in deflecting the attacks of birds to a non-vulnerable area.  

Cloudless sulpher caterpillar
Many caterpillars are quite difficult to find due to their camouflage and these two are no exception. The remarkably colored banded sphinx is a classic example of disruptive coloration and was found on a primrose willow; surprisingly its "coat of many colors" makes it cryptic. The cloudless sulphur caterpillar has a very different type of design that mimics the color and pattern of its food plant of senna/cassia quite well.  

Female softshell turtle
When I found a large female softshell turtle in early December on land at Wildflower Preserve I knew that it was looking for a sandy site to lay its eggs. Aside from occasional times of basking, these highly aquatic turtles rarely leave the water.  They are even able to obtain oxygen under water across their skin and the mucous membranes of the throat. They compensate for their lack of a protective bony shell by their rapid swimming speed and a snappy disposition.

Eagle at nest in preserve
Winter is the time for eagles to breed despite the warm weather and this impressive adult bald eagle was working on a nest along the Myakka River.

Flock of skimmers at Chadwick Beach
Most beach birds breed in the spring/summer, sometimes locally but often far to the north, and spend the winter feeding and resting along our beaches.  Some of the best mixed flocks can be found at public parks such as Chadwick Beach on Manasota Key where they are mostly protected from people, dogs and other predators and feel safe.  It is a win win situation where the birds benefit and people can enjoy them.  

Black skimmer
An up close view of one of the many black skimmers is memorable and emphasizes the improbability of the bizarre bill structure.  I think that if this bird were only known from fossils, we would find it difficult to believe that they could actually feed by skimming small fish from the water's surface.

Snowy plover
One of my most interesting beach finds was this snowy plover with holiday bling on its legs.  It had yellow/yellow bands on its upper left leg and orange/black bands on its upper right leg.  By contacting I was able to identify this as a male snowy plover banded on its nest area in the Gulf Islands National Seashore near Pensacola, FL, in the summer of 2014.  I had photographed this very same plover on Dec. 25, 2014, in almost the same spot on Palm Island just south of Stump Pass.  I found it again a year later on Dec. 10, 2015, a remarkable illustration of the site fidelity of birds which tend to move to the same places year after year to breed and during migration.

So let us all be eternally thankful for nature's fantastic bounty of wild creatures and work to protect them and their habitats.

Bill Dunson 
Englewood, FL and Galax, VA

Thursday, December 17, 2015

Barrier Island Wonders of Nature‏

Snowy egret fishing off dock
Barrier Islands are unique habitats at the intersection of land and sea.  They are beautiful but highly impacted by humans seeking the classic beach experience, but they can also provide a place to observe unusual species that are highly specialized for this edge environment.  I live on a gulf front barrier island, Manasota Key, and often visit the adjacent island to the south, Palm/Knight Island.

Fighting conchs on the beach at Palm Island
A recent morning walk at low tide on Palm Island revealed an unusual phenomenon, the stranding of large numbers of fighting conchs.  These snails are true conchs and close relatives of the huge queen conchs, which are now virtually extinct in FL.  

Fighting conch
Fighting conchs are herbivores and often have a rich reddish color to the shell opening, the purpose of which is a mystery to me. They apparently feed sub-tidally close to the shore and can get stranded on the beach during a very low tide. Since they are not very mobile they dig into the sand to minimize desiccation until the next high tide.  I sometimes walk along throwing them back into the water, although one could argue that this is a natural circumstance and that humans should not interfere.

Calico crab
Another interesting critter stranded on the beach was a calico crab.  This is one of the so-called "box" crabs, since when threatened it holds its claws up against its shell in a protective stance.  This may enhance the attractive blotched cryptic coloration by changing the outline and diminish predation.  Since this is an aquatic crab, unlike the ghost crab, it dies rapidly on the beach.

White-tipped black moth
Just behind the beach in the drier dune area of Manasota Key I came across a breeding aggregation of very interesting white-tipped black moths (Melanchroia).  They appear to mimic wasps as a protective mechanism  that allows them to fly in daytime.  Since they feed predominantly on plants in the spurge family which are usually toxic, they may also retain the food toxins and advertise this by their bright coloration.  This would give them a one-two punch against bird predators.  But it is a mystery why so many of these moths were close to the beach when their larval food plants did not seem to be present. These moths are in the inchworm or geometer family yet they strongly resemble unrelated ctenucha moths in the tiger moth family, perhaps an example of both mimicking wasps, but certainly a remarkable example of convergent evolution.  

Tennessee warbler
Continuing to the east across the barrier island from the gulf to the bay, I entered a deciduous woodland which is suitable for terrestrial birds and can be a hot spot for migrants.  For example on Nov. 11, I saw both Tennessee warblers and a yellow billed cuckoo which were flying south for the winter.  The warbler breeds in the Canadian boreal forest and winters in Central America and Cuba.  

Yellow-billed cuckoo
The cuckoo breeds throughout eastern N America and winters in S America. It is a thrill to see these neo-tropical birds while they are on their remarkable flights and think about how such amazing long distance patterns of movement might have originated.

Mangrove snake
Continuing eastward I found myself in the bayside mangroves and encountered one of our least known local reptiles, the mangrove snake. This is a salt water specialist but is not a true sea snake (which are mainly venomous species living in the Pacific and Indian oceans) but is in the same genus as the fresh water banded water snake.  It lacks the salt gland used by sea snakes to maintain its blood concentration about one third that of sea water, but regulates osmotic balance by being relatively impermeable, by gaining fresh water from its fish prey, and by only drinking brackish or fresh water when it is available from rain.  Another unusual fact is that the mangrove snake comes in a wide variety of colors from this reddish morph to gray or blackish hues.  Certainly the red morph blends well into the red mangrove root habitat.

White pelicans on spoil island, Gasparilla Sound
Further east in the bay I saw a a large aggregation of white pelicans, huge spectacular birds that breed in shallow lakes of the northern Great Plains, and soar long distances with minimal energetic cost for flight.  They are certainly majestic birds in flight and their arrival in Florida in early November is an annually anticipated event.  They feed in groups and do not dive as do the smaller brown pelicans.  Another white bird, the snowy egret is famous for its flexibility in feeding strategies and this one found that it could efficiently catch fish by leaning off a bayside dock.  Such an ability to adjust behavior to new situations seems to be crucial for survival in an increasingly human altered world.

So the next time you visit a beach on a barrier island, look around and enjoy the remarkable variety of life that is often only found on these narrow and fragile ribbons of sand.

Bill Dunson 
Englewood, FL and Galax, VA

Sunday, December 6, 2015

Photos from Myakka Island Point Preserve

Bald eagle nest

Bald eagle

Banded sphinx caterpillar

Banded sphinx caterpillar

We had a great walk today at Myakka Island Pt Preserve so I hope you have seen its potential as part of a regular series of nature walks for your group (North Port Friends of Wildlife).  I would enjoy helping out if you need me to lead occasional walks.

I attach some photos for use on your web site in case you did not get better ones of the impressive bald eagle at the nest and the banded sphinx caterpillar on primrose willow.  It is very interesting how the same caterpillar seen from upside down and right side up is rather different in appearance.  I assume this striking pattern is a disruptive and camouflage mechanism to avoid  predation by birds.

Cheers- Bill

Tuesday, December 1, 2015

Thanksgiving squirrel meal‏

This grey squirrel in our yard did not have access to cranberries for its Thanksgiving dinner so it made do with the next best thing- red pyracantha berries.  This Asiastic firethorn bush has been prolific in producing fruit for the twenty years we have been here and the squirrels, mockingbirds, catbirds and especially robins always enjoy the fruit during the winter.  This year one squirrel got hungry earlier than usual and had a turkey day snack. 

Bill Dunson