Monday, March 30, 2015

Spring Has Sprung, Sort Of‏

Spotted sandpiper at Florida dock
The disconnect between calendar Spring and that recognized by animals continues.  March 20 has come and gone but there is a great deal of northward migration still to come. On the other hand warm weather has brought out many insects, some frogs are calling, and our first trans Gulf warbler,  the marvelous hooded, has arrived in our FL yard.  

Gulf fritillary butterfly
Nothing says spring more than beautiful butterflies flitting around the yard.  While we have had zebras all winter, the appearance of this newly emerged and brilliant male Gulf fritillary definitely shows how the season is changing.  The males of this species are much brighter than the females and presumably attract females by their showy coloration.  This pattern seems to be an example of toxic Muellerian mimicry of the milkweed-feeding monarchs, although based on chemicals derived from passionvines.  

Male twilight darner in Florida yard
Some other insects attracting attention this time of year are the dragonflies, that need warm sunny weather for their complex flight.  A huge twilight darner flew into our open door and gave me an opportunity to examine it up close and personal.  This species is limited to FL and extreme southern GA.  
Male Eastern pondhawk dragonfly

In contrast ferocious eastern pondhawks are quite common now and will be seen widely throughout  the eastern US.  The males are bluish and the females greenish, another of many examples of sexual dimorphism in dragonflies.  I watched a female laying eggs in the water and her mate flew immediately above her to protect her from intruding males.  The complexity of the reproductive patterns in these primitive insects amazes me.

Great blue heron drinks from Florida yard water bath
I always make a number of interesting observations of wildlife in our bay-front yard and the recent period in late March has been no exception.  A great blue heron came up to one of our bird baths and managed to get some fresh water to drink despite the unsuitability of its bill for this purpose.  There is of course no natural fresh water on our island so many birds are attracted to fresh water in a bath, but I was surprised that the great blue was interested since it presumably has a salt gland to allow it to drink salt water.  

Catbird in Florida yard bath
A catbird also came to the bath and illustrated that it has yet to migrate north to its breeding grounds; they do not breed in southern FL  strangely enough.  Great egrets often forage in the yard searching mainly for brown anoles; indeed this exotic lizard is now the basis of the food chain for many native birds and snakes.  But this egret had caught a SE five lined skink, a slippery and potentially toxic prize which is reputed to be poisonous to eat.  On our dock a spotted sandpiper, just starting to get its lovely spotted breast, lingered for a while on its way north to breed.

Spoonbill in group of 16 at Lemon Lake
At nearby estuarine Lemon Lake we have continued to enjoy the fabulous roseate spoonbills which are feeding on prey concentrated by declining water levels.  They will be breeding nearby, in contrast with the few remaining blue-winged teal which should already have been winging their way northward.  

Blue winged teal at Lemon Lake
So while spring is definitely underway, many species are still taking their sweet time to go north.  Are they lazy, addicted to FL sunshine, or just inefficient?  It seems likely that the timing of migration is often set to coincide with the most appropriate period in which to establish territories and obtain food for young on breeding grounds.  Thus species and individuals which breed very far north may lag behind those which are moving to lower latitudes.  

Bill Dunson
Englewood, FL and Galax, VA

Thursday, March 26, 2015

Let's Have Lizard for Lunch‏

This great egret caught a skink in my yard on Manasota Key and played with it for a while before swallowing.  This is interesting on two levels. First this aquatic wading bird is foraging for reptiles on dry land, and thus showing flexible behavior, one reason great egrets are doing so well compared to some other declining species.  Second this southeastern five-lined skink is thought to be toxic to mammals, so I wonder if the egret suffered any ill effects.  

Bill Dunson

Spoonbill alert at Lemon Lake‏

Roseate spoonbills are always a possibility at tidal Lemon Lake within Amberjack Preserve, Charlotte County, FL.  But they are unpredictable and are best seen when the lake level is declining due to hot weather facilitating evaporation, and low rainfall.  I was at Lemon Lake the morning of March 23 and found that the upper or eastern end of the lake was bare mud and many birds including a flock of 16 spoonbills was resting near the western or lower boardwalk.  They are likely feeding mainly on the abundant sheepshead minnow (Cyprinodon) which is a herbivore that thrives in the shallow brackish water, plus any small invertebrates that are concentrated by the falling water levels.

Bill Dunson

Screechie in the date palm tree

Red male screech owl in pygmy date palm

Screech owl in yard box

Hi Nancy and Dave-

Concerning your desire to maximize your native plant species in your Rotonda yard by removing exotics:

Do NOT cut down your exotic pygmy date palm !!!  We have had a red morph male screech owl roosting in our pygmy date palm for years with his presumed female in a nearby box.  He obviously prefers this palm, for its protective spines perhaps, over a lot of alternative native vegetation.  The native vegetation can be used to make a clump of shrubs around the date to provide additional cover.  I have added a second box recently about 100 feet away in the front yard to see if we can attract a second pair.

This is a great example of how a mix of selected non-invasive exotic plants and native plants can enhance the wildlife habitat in your yard.

Another example is the osprey nest in our yard on top of a Norfolk Island pine.

Feel free to stop by (call first at 276-233-6364 cell and text) and see how this has worked for us.

Bill Dunson

A Late Winter Nature Walk in SW Florida‏

Male goldfinch molting to breeding plumage

A male goldfinch I spotted drinking from our backyard water drip expresses very well the winter to spring transition this time of year.  It  is a "half and half" yellow bird which is re-growing its iconic yellow feathers in preparation for its journey back north.  

Many plants are flowering here in Florida such as the tropical Tabebuia with its canopy of amazing pink flowers.  

Tropical tabebuia - pink
The sea hibiscus is in full bloom; the flowers are yellow when they first come out and change to pinkish red during a day or so.  This could be a signal that the flower is old and thus unattractive to pollinators.  Or it might signal the opposite, as being open for business but to a different group of insects more attracted to reddish flowers.

Sea hibiscus - pink

Sea hibiscus 

Western sandpiper on the Spit
Two wintering sandpipers seen close together on the Palm Island beach were the least and western sandpipers, differing mainly by the color of their legs. Both will soon be leaving to breed in the Arctic but do not yet show any breeding coloration.  They may not be too anxious to arrive on the frigid breeding grounds before the weather is suitable.
Forsters tern
Among a group of royal terns nearby. some show increases in the amount of black feathers on the cap, but are not yet fully changed into breeding condition. They breed nearby along the Gulf and Atlantic coasts.   An adjacent Forster's tern is still in non-breeding plumage; they breed both along the coast and inland, mostly south of Canada.

Spotted sandpiper
A spotted sandpiper on the same beach is barely showing the development of the distinct spots which will distinguish breeding birds.  

Least sandpipers on the Spit

Thus although some birds are migrating northwards, many have yet to either migrate or to develop their full breeding coloration.  But there are reports of tree swallows and some other migrants moving north to VA, so some migration is underway.  Bird song is picking up although we are yet to see any substantial number of spring migrants passing through SW FL from Central and South America.  But the time is very close for that most exciting time of year- spring migration of our N American breeding birds that winter in southern latitudes.
Royal terns Palm Island

Bill Dunson
Englewood, FL, and Galax, VA

I see you!‏

Red morph screech owl

This tiny red morph male screech owl sits in a tree in our backyard acting like a leaf or twig and doing a good job of camouflage with its tall "ear" tuffs.  His female is in a box nearby and you are likely to attract a couple of "screechies" if you put out a box in your yard anywhere in the eastern US.

Bill Dunson

Tuesday, March 17, 2015

Up close and personal with horseshoe crabs‏

My 12 year old grandson, Isaac Dunson (left), and his friend, Drew Oligschlaeger (right), are visiting us from Salt Lake City.  They are getting an in depth introduction to boating and marine critters and are here seen inspecting some horseshoe crabs they caught near Little Gasparilla Island.  They both seem a little suspicious that these ancient spider relatives are harmless.

Bill Dunson

Paddleboarding at Palm Island‏

Isaac Dunson paddleboarding on Palm Island

My grandson 12 year old Isaac Dunson is visiting us from Salt Lake City.  He is having a ball learning how to paddleboard on Palm Island even though the waves are a bit challenging.

Bill Dunson

Friday, March 13, 2015

A Low Tide Bonanza of Life

We have recently had a series of very low tides and this has revealed some interesting animals either on the beach or on shallow flats.  
Horse conch on beach at Stump Pass
The state shell of Florida is the magnificent horse conch which has a bright red body and foot. It is not a true conch but is more closely related to the tulip shells.  I have often wondered about the striking red body color and its purpose but have found no answer.  The horse conch is predatory on other molluscs and is the largest gastropod in American waters.  

Lightning whelk eating a clam in Bocilla Lagoon
A slightly smaller marine gastropod and food for the horse conch is the lightning whelk, which is unusual in that it is sinistral or left handed.  If you hold the shell by its front or pointed end facing down, the flared part of the shell where the foot emerges is to the left side.  I came across a large adult feeding on a hard clam on a tidal flat.  They lay their eggs in a long string of capsules which are sometimes washed onto the beach.

Whelk shell with anemones at Stump Pass
I found a small lightning whelk shell washed up on the beach which was empty, although it likely had a hermit crab in it previously.  But the most interesting feature was the attachment of three symbiotic anemones (Calliactis) to the shell.  

These of course are retracted when out of the water but they benefit from attaching to the mollusc shells inhabited by hermit crabs and probably also provide some protection and perhaps food to the crab with their stinging tentacles.

Moon snail egg collar
A smaller marine gastropod, the moon snail, lays its eggs in a collar mixed with sand.  It has been shown that the design of this collar is useful in maintaining the eggs on top of the sediment and upright.  The moon snail bores through the shells of its prey with an acidic secretion.

Sea squirts on flat in Bocilla Lagoon
My grandkids' favorite marine invertebrates are the sea squirts which as adults are sessile tunicates fixed to the bottom or some hard object.  They are filter feeders and have an internal compartment filled with water.  When squeezed they squirt the water out in a fine stream- they thus become nature's water pistol !  They are interesting since they have a free swimming larvae which is similar in structure to the early chordates/vertebrates and are indeed in the same phylum despite their strange morphology.

Cassiopea jellyfish in Bocilla Lagoon

My favorite jellyfish is the upside down jelly or Cassiopea.  It has symbiotic algae in its tissues and lies on its back to gather sun for the algae.  It appears to be a photosynthetic animal/plant partnership which also obtains food from catching zooplankton with its venomous nematocysts.  It is a warm water species and is only occasionally found in numbers in our area of SW FL.  Indeed during my 20 years of experience in this area it has rarely been able to overwinter and grow to a large size.  Thus global warming has apparently not yet had a significant effect on its ability to colonize more northern habitats.  

Lightning whelk egg capules at the Spit
So keep an eye on the tide tables and weather events such as strong winds which can contribute to the occurrence of exceptionally low tides.  This is an opportunity to observe some fascinating subtidal animals which otherwise are not easily seen.

Bill Dunson
Englewood, FL and Galax, VA

Wednesday, March 4, 2015

Snowbird of a Different Sort‏

Cooper's hawk 2-25-15, Chapel Hill, NC
"Snowbird" usually refers to a person who leaves the north and goes to Florida in winter to avoid the cold weather.  This photo taken recently in my son's yard in Chapel Hill, NC, shows a different type.  This is a Cooper's hawk in deep snow, very unusual for the Piedmont of NC, looking for a tasty snack of a bird coming to the bird feeder.  I am sure it wishes it had migrated south !  

Bill Dunson