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 bandedbirds.org 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

Wednesday, November 25, 2015

Butterfly News from SW FL

Some of you might enjoy seeing this butterfly newsletter from the Punta Gorda, Pt Charlotte, FL, area. It is packed with information and interesting trip reports.

Peace River Butterfly Society Newsletter -- November 2015

Bill

Saturday, November 21, 2015

Bird Brained ?‏

Snowy egret fishing at FL dock

Snowy egrets are known to be very versatile in their fishing styles which involve a variety of different ways to catch fish by wading.  Their most famous technique is the "snowy shuffle" in which their bright yellow feet are used to scare up small prey which are then grabbed by the beak.  But all of these procedures involve wading, and a limitation to water no deeper than their legs. This young genius snowy figured out that it can fish in deeper waters from our dock, but a "snowy stoop" is involved to reach the surface of the water from the dock.  As I watched, this bird was successful in catching several small minnows. So "bird brained" is not a bad thing from the perspective of this ability to solve a problem with a new idea.  Indeed the future of birds within a rapidly changing world so profoundly affected by humans could be largely dependent on such flexibility in behavior.

Bill Dunson
Englewood, FL

Nature walks by Bill Dunson in Nov/Dec 2015

Here are notices for four nature walks in SW FL sponsored by the Lemon Bay Conservancy which I am leading during Nov and Dec, 2015. No reservations required, meet in the parking lots,  and no fees except for parking at Stump Pass.  Please circulate this to your members.

Nov. 30:  Edible and medicinal plants at Wildflower Preserve. 3120 Gasparilla Pines Blvd. Englewood, FL. 9-11 am. A  short walk around the 80 acre restored golf course owned by the Lemon Bay Conservancy to examine the useful and toxic properties of plants and their animal herbivores and predators.

Dec. 4:  Hike the Duisberg Nature Trail and the beach at Middle Beach Park. 6725 Manasota Key Rd. Venice/Englewood, FL. 9-11 am.  A short hike up the nature trail and back on the beach to examine the natural history of a sub-tropical hammock, mangroves, and beach dunes.  

Dec. 11:  Hike about 1.5 miles round trip in Wildflower Preserve, 3120 Gasparilla Pines Blvd., Englewood, FL, to tidal Lemon Creek.  This is habitat for juvenile tarpon and we will discuss the ecology of such young fish living in hypoxic mangrove waters and efforts being made to study and restore/create habitat.  9-11:30 am. 

Dec. 18:  Hike about 2.5 miles round trip to Stump Pass within Stump Pass State Park (entry fee), Englewood, FL.  We will study the natural history of the beach, dune, back dune  and mangrove areas and discuss the current efforts to stabilize and re-nourish the eroding beach, and dredge the channel.  9-11:30 am. 

Dr Bill Dunson
wdunson@comcast.net
276-233-6364 cell text

Friday, November 13, 2015

Nature is HOT in Florida Fall‏

Although I am generally anxious to leave our VA farm soon after the first frost, this year it has been unexpectedly warm in FL even into November.  This is a shock to humans unused to such hot and muggy weather, but it yields a bonus in that critters tend to be more active and plants flourish.

Lynx spider green female with egg mass 
This green lynx spider is guarding her eggs.  She does this apparently without eating and her shrunken abdomen illustrates her devotion to her progeny.  Such maternal behavior in higher life forms is considered commendable and even altruistic, but this illustrates how even primitive species are equally devoted to protection of their babies due to the evolutionary imperative to procreate their genes.    

Great pondhawk Bronco Rd FL 
I was happy to get this photo of a great pondhawk dragonfly, which I do not see very often; it is limited to S FL in the eastern US.  It has a huge thorax and a slender abdomen and is a rapacious predator on insects.  It is somewhat unusual in that the coloration of both sexes are similar and they strongly resemble the female (but not the bluish male) smaller eastern pondhawk.
There is so much we do not understand about the significance of such variation in color and pattern.

Hairstreak on mallow scrub
A very confusing group of butterflies is the hairstreaks.  On a hike in Charlotte Flatwoods Preserve we came across a number of the mallow scrub hairstreak which is restricted to S FL.  Not only are there other types of similar hairstreaks, but they also resemble the blues, both of which are tiny and require some study to identify.  Aside from the challenge of identification, I find these butterflies fascinating because of their unusual color and pattern.  The eye spot on the outer hindwing and the short "tails" appear to be an head mimic that is designed by evolution to divert the attack of  close-up predators such as jumping spiders away from the vulnerable head and body.  At a distance this butterfly is well camouflaged.

Clouded sulphur on salvia 
A butterfly that is certainly conspicuous is this clouded sulphur which is bright yellow, shown here drinking nectar on some red salvia flowers.  But its seems to limit predation by flying not only fast, but in an erratic pattern with short stops at flowers.  



Box turtle plastron
Box turtle carapace
The opposite extreme in animal locomotion is this FL box turtle which can only defend itself by closing up inside its shell when attacked.  The patterns on both the upper (carapace) and lower (plastron) shell are quite striking and illustrate how artistic natural coloration can be.  It might be that such beautiful patterns of the upper shell are actually a type of camouflage since they may disguise the shell by breaking up its outline in the dappled shade and sun of the forest floor.  

Coot among floating hearts
On a visit to Red Bug Preserve in Sarasota I found this coot feeding among the blooming floating hearts.  Not only was this a charming scene, it illustrates how coots and moorhens feed by picking up plant and animal material from the shallow surface waters.  The apparent decline of such birds that feed on shallow vegetation in lakes appears to be due to competition with the introduced African tilapia fish which is very common now in fresh water lakes.

Birds at FL dock
Wading birds are attracted to natural features of our yard which lies along the shores of Lemon Bay.  Thus in this photo you can see a little blue heron on the dock, and a single snowy egret and a group of white ibis feeding along the waters edge.  Such a mixed species flock seems to be of mutual benefit if contrasting feeding styles yield prey that may be less available when the species feed alone.  

Yellow throated warbler at FL yard water drip
Perching birds or passerines are primarily attracted in our barrier island yard to fresh water supplied by a drip; this yellow throated warbler likes to drink directly from the drip and then go down to the bowl and bathe.  

Soon enough we will be shivering from the periodic NE winds of cold fronts, but for now we enjoy the sultry southern breezes and the active behavior of animals uninhibited by cooler weather.

Bill Dunson 
Englewood, FL 

Sunday, October 25, 2015

A shorebird with bling of a different kind


On Oct. 18, 2015, while walking along the beach on Palm Island, Charlotte County FL, just south of Stump Pass, I noticed one tiny shorebird, a sanderling, that had bands on its legs. This bling was unusual since there were orange bands on both lower legs, a silver band on the upper left, and a blue band and blank white flag on the upper right leg.  There is an on-line website (bandedbirds.org) that allows banded birds to be individually identified if they carry numbered flags, but this combination of bands without a lettered code was confusing.

I contacted the administrator of the website and eventually found that this bird was banded at Chaplin Lake, Saskatchewan, Canada, as a group or cohort of birds caught in the springs of 2012-2014.  This bird was presumably headed to its breeding site in the high Arctic about 1200 miles away along the northern tundra of Canada when banded.  It is now on the SW FL coast where it may spend the winter or head further south.

The direct line distance between Chaplin Lake and Palm Island is about 2000 miles.  Chaplin Lake is unusual in that, like the Great Salt Lake in Utah, it is saline and produces large numbers of brine flies and fairy shrimp that are avidly consumed by vast numbers of migrating shorebirds.  

So the sanderlings which scurry along the beaches in FL are remarkable hemispheric travelers which depend on the health of delicate natural habitats in different countries.  They are tiny (about 2 oz) and their ability to make such a fantastic migratory journey of at least 6000 miles for each round trip over many years is almost beyond comprehension.  

Bill Dunson

Friday, October 23, 2015

Aerial cannibals !

If you are at the beach you might look up and notice that an interesting migration of dragonflies is taking place just over your head.  Dragonflies are heading south to escape the frozen north in considerable numbers and I watched many common green darners passing by at Caspersen beach, Venice, FL, on Oct. 21.  
 
It may surprise you that relatively primitive insects such as dragonflies are capable of such long distance migration.  They are extraordinary flyers but they apparently get hungry while flying and their appetites take a bizarre turn.  This species is common around our farm ponds in VA so it is interesting to see where they go when they leave and are replaced by the equally large, but cool weather tolerant shadow darner.
 
I saw several twosomes of common green darner dragonflies writhing on the road and on closer inspection realized that one of the pair was eating the other! The dragonfly on top had its jaws embedded into the thorax of the victim. I knew that falcons often eat migrating dragonflies but did not realize that these predaceous insects could and would eat their own species.  

Bill Dunson
Englewood, FL

Saturday, September 19, 2015

Signs of Fall

Ginseng at farm
Although signs of the fall season are usually evident enough from changes in the weather, there are many clues from nature that a seismic shift in the seasons is occurring.  Even if you did not have a calendar, you should be able to predict the month if you study the many signs that nature provides.
During a recent walk on our farm I picked up a handful of nuts from the forest floor.  Can you identify  the acorns, shagbark hickory nuts, black walnut, buckeye, hazelnut, and chinquapin?  These provide a bountiful crop for wildlife to harvest and hide away for the future.  Many such nuts are never recovered by rodents and germinate.  
Nanny berry
There are many soft fruits in the forest including this nannyberry.  It is Viburnum lentago and is one of many viburnums which produce "haw" fruit which are prized by animals of all kinds.  The variation in fruit color is interesting since it illustrates how plants communicate the ripeness of their fruits to frugivores.  It would be disadvantageous for the fruits to be eaten before they are ripe, since the seeds are not mature, so unripe fruits are often unpalatable or even poisonous. The change in color from green to red, yellow or black that signals ripeness is easily recognized and is so familiar to us that we often fail to understand the evolutionary meaning. 
 
Indian grass at farm
Grasses are also producing seeds and I here illustrate this with one of my favorites, Indiangrass.  Grasses do not have pretty flowers and they are wind pollinated so we do not always consider them to be beneficial to animals.  But the seeds are eaten by a wide variety of birds and over an extended period.  So it is important to allow grasses to flower and mature seeds in the fall and leave them in the fields during the fall and winter as wildlife food.  Grasses can also be quite beautiful at this stage of growth.
 

Shadow darner
One distinct sign of fall around our ponds is the rapid decline in insect activity and a change in the species present.  For example the large common green darner migrates south and is replaced by the similarly sized shadow darner.

Yellow legged meadowhawk
The autumn or yellow legged meadowhawk is the last dragonfly to emerge in the north and likely the last one seen before winter.  The male shown here is a beautiful red color to advertise its virility.  The appearance of odonate species that specialize in cooler conditions seems to be a classic case of avoidance of competition by a temporal shift in activity.

Tiger swallowtail caterpillar near pupation 
Eastern tiger swallowtails are a common butterfly in our area but we almost never find the caterpillars which feed on black cherry and tulip poplar. This caterpillar found its way to our porch and has changed from green to brown as it approaches the time for pupation.  It has two false eye spots which may confuse avian predators into thinking it is a scary snake.  In addition when disturbed it protrudes an osmeterium which looks very much like the tongue of a snake.   These mechanisms to avoid predation illustrate how intense the efforts of birds are to find and eat caterpillars, and how gullible birds can be when confronted by these elaborate ruses.  

Golden garden spider
When I see large golden garden spiders on their webs I know it is fall.  These spiders over-winter as eggs or young spiders and gradually grow to an adult size over the summer.  The large female builds a characteristic orb web with distinctive  zig-zag patterns called stabilimenta that strengthen the web, and may attract insects and warn birds not to fly into the web.  

Red shouldered hawk
The migration of hawks is a characteristic fall phenomenon and I recently noticed this juvenile red shouldered hawk in a tree on our farm.  The juvenile plumage pattern seems to be good camouflage and signals a lack of maturity to adult hawks.  We do not see red shouldered hawks during the breeding season so this must be a bird that is migrating south.  They make use of rising currents of warm air or thermals to minimize their energetic cost of long distance flight.

Although the arrival of fall signals the end of the growing season for most animals and plants, it is a time of many changes in the world of natural history that are of great interest.  So get out and enjoy the beauties of fall and observe how a few species wax while most others wane in abundance.

Bill Dunson Galax, VA and Englewood, FL 

Tuesday, September 15, 2015

Fwd: Bee? On fire cracker bush?

 
The message below was an answer I sent to a friend in Venice, FL, who asked me about a so-called "fire cracker" plant in his yard that was visited by bees.

 
Hi Tom-

A very nice photo and getting the bee in flight is hard!

This is not a fire cracker plant but a native firebush, Hamelia patens.  The name firecracker is usually applied to Russelia , a native of Mexico, which has somewhat similar flowers but very different leaves  ( https://en.wikipedia.org/wiki/Russelia).  

I predict that the bumblebee will not be able to drink nectar from the firebush flower without biting the base of the flower and stealing the nectar.  The corolla tube is far too long for its tongue and too narrow.  Watch the bee closely when it lands on the flower and see what it does- I predict it will go to the base of the flower tube and bite through.  I see this all the time with honeybees on Cape honeysuckle flowers, and some bees on flowers of Abelia.  

I have seen mainly zebra (longwings), gulf fritillaries and hummingbirds on flowers of firebush.  They have long and narrow tongues which can reach the base of the flower.

Firebush is the champion great bush for the yard since it provides nectar, fruit and cover for insects and birds.  It is however quite sensitive to frosts and will be frozen back if planted inland.  It is also mainly a summer bloomer.


Bill



To: wdunson@comcast.net
Sent: Saturday, September 12, 2015 10:57:20 AM
Subject: Bee? On fire cracker bush?

HI BILL
HERE IS PIC OF BEE? TOOK US SOME TIME TO GET.   CONNIE AN TOM

Sent from my Verizon 4G LTE Tablet
CONNIE AN TOM 

Wednesday, September 9, 2015

Those Beautiful Blue Flowers of Fall‏

Monarch on blue mistflower or ageratum
Although there are wide variations in flower color at all seasons, I tend to think as summer as being the time of many yellow flowers of the aster family.   Hence the derivation of the term for the many often unidentified yellow composites/ asters as "DYC," or darn yellow composites! 


Bumblebee on blue mistflower
Here in SW VA in fall we continue to have many yellow flowers such as goldenrod, but it is also the time for spectacular blue flowers, many of which are specialized for pollination by bees, especially bumblebees.  Bumblebees are physiologically adapted for foraging in cooler fall temperatures due to their ability to raise their body temperature by muscular contractions.  Thus when I go out on an early fall morning, it is cool and there are primarily bumblebees on flowers.

Yellow scape on blue mistflower
A very popular flower in the aster family for many insects in our September yard is the blue mistflower or ageratum.  It has a flat flower shape that is attractive to a wide variety of insects.  For example here are some photos of a monarch, a bumblebee and a yellow collared scape/tiger moth on mistflower.  

Lobelia
In contrast some of the lobelias in the bluebell family attract specific pollinators.  The spectacular great blue lobelia which blooms in late summer and early fall in our area is primarily pollinated by bumblebees.  Yet a close relative, the bright red cardinal flower, primarily blooms earlier and is usually pollinated by hummingbirds.


Blue monkshood

The color blue seems to be an attractant for bumblebees which may not perceive red as a distinct color.  Thus the fall-blooming blue curls (mint family) is pollinated by native bees.  The fall blooming deep blue monkshood (buttercup family) is a bumblebee specialist.  

Blue curls Trichostema
The more you learn about flowers, the more complex their structures and functions are revealed to be.  Yet there are common evolutionary themes that begin to reveal themselves when you look for patterns.  One of the more interesting is the relation between flower color, structure and the pollinator(s) for which the flowers are most attractive.  So when you go out to commune with nature don't just smell the flowers, look carefully at them and the pollinators that they attract.   

Bill Dunson 
Galax, VA and Englewood, FL