Thursday, January 29, 2015

Natural Wonders of January in SW Florida

We have had at least one light frost within five miles of our house in December and a series of cold fronts in January on an almost weekly basis.  But temperatures soar into the high 70's and even 80's in between these cooler periods.  Flowering of native plants is at a low ebb at this time and insect life does diminish.  But there are many aspects of natural history that continue to provide fascination for the naturalist.

For example I came across one example of a wonderful flower, the seaside gentian which I have never seen before.  It is unusual in that it grows close behind the beach dunes and does not seem to be obviously adapted for this periodically salty and dry habitat.  It was also blooming far earlier than normal since it is typically a summer bloomer, when the rains are much more abundant.  One of those many mysteries of nature I guess.

Another fortuitous discovery was a female polyphemus silkmoth fluttering at the base of an oak tree.  This is one of the largest of our moths and one of the most striking.  When undisturbed it is well camouflaged but if prodded it opens its hind wings to reveal the most amazing eye spots.  Clearly this behavior and coloration are designed to strike fear or at least caution into potentially predatory birds.  

The large eye spots must mimic an owl's face or perhaps snake eyes and their fine structure is quite detailed indicating that evolutionary selection has refined the basic eye spot into a more specific eye mimic.
On cool and sunny days reptiles are often seen basking and a presumed female alligator was found with a number of babies clustered on her head and back.  

Gators are known to be quite maternal and these young ones must represent last year's brood which she is still protecting. Her blood may be "cold" but her heart is warm! Since crocodilians are the surviving archosaurs or ruling reptiles this indicates that the dinosaurs may have had complex behavioral patterns also. Since baby gators are just a snack for many predators the continued protection of the mother may be very important for their survival.

Bald eagles are raising their young now and this photo was taken Jan. 16 at a nest along the Pioneer Bike Trail just south of the East Branch of Coral Creek. Unlike most birds they are winter breeders which may be related to their food supply and the long period of development necessary for these young raptors. 

For such a strong predator it is touching to see how carefully the adult pulls off small pieces of food and hands them to her babies (two in this case).  Young eagles go through about four years of maturation and changes in plumage before becoming the iconic adults we are so familiar with.  

Great blue heron
Great white heron
An unusual sighting at Myakka State Park was a great white heron, a southern morph of the great blue.  I show photos of the great white for comparison with a great blue on my dock.  The great white has yellow legs and shorter head plumes in addition to being white.  The great egret is much smaller with dark legs. The occurrence of dark and white morphs in wading birds is common and it seems that such variation must be related to differences in feeding efficiency for different prey and possibly different feeding behaviors.  

Standing close to the great white at the park was a wood stork which has a very different feeding behavior- it wades in shallow water with its bill open and shuffles its bright pink feet to scare up prey.  Creatures that touch its bill are caught by an extremely rapid snap of the bill cued only by touch.  The smaller snowy egret uses a similar "snowy shuffle" of its bright yellow feet to scare up prey which are speared by a visually directed jab of the beak.  All of these variations in morphology and behavior seem designed for avoidance of competition among the various species of wading birds.

So wherever winter finds you, go out and enjoy the glories and mysteries of nature.

Bill Dunson
Englewood, FL and Galax, VA

Sunday, January 25, 2015

Life's a Beach

For many folks life is time spent at the beach, so this shell sculpture spelling out LIFE and made up of cockle shells found at the Palm Island beach is very appropriate.  We are very fortunate to have many beautiful beaches in the area that are enjoyed both by humans and beach dwelling animals.

Bill Dunson

Beach Valentine‏

I found this interesting heart made of Florida fighting conch shells left by a visitor to Palm Island beach.  Perhaps this is the unusual valentine you may be searching for?  The use of "fighting" conchs is also fascinating- choosing a shell known for aggression as a symbol of love?

Bill Dunson

Mommie Dearest

This gator Mom at Myakka State Park has a bunch of her babies from last nesting season piled on her back and head.  It is always amazing to me that a "cold blooded reptile" shows such maternal care for so many months after the hatching of the young.  

Bill Dunson

Monday, January 19, 2015

Find the birdie !‏

An adult yellow crowned night heron hangs out in our backyard mangroves but I often do not even notice that it is there.  Despite rather bright plumage it blends in well with the dappled colors and patterns of the mangroves.  After an afternoon quiet time, it will be off to hunt for crabs at dusk.  It has a heavier bill than most herons, well suited for cracking crab shells.

Bill Dunson

The Eagles Have landed !‏

A huge bonus of biking the wonderful Pioneer Bike Trail from route 776 south to Placida is that there is an active eagle nest close to the trail and just south of the bridge over the east branch of Coral Creek.  There are two large babies in the nest in a spectacular dead pine tree.  I got some good views of one parent feeding the chicks.  Eagles almost always choose a site near good fishing waters and this one certainly fits the bill since the shallow waters of the creek are loaded with fish.  So take your bike down the trail and enjoy nature at its best.

Bill Dunson 

Thursday, January 15, 2015

Article: Parasite on Tropical Milkweed Harmful to Monarchs‏

Here is an article that will cause people to reconsider planting tropical milkweed, Asclepias curassavica, for Monarchs.  I know we have all heard about this issue before but here is more information on the topic.


Monarch butterfly
Plan to save monarch butterflies backfires
Lizzie is Science's Latin America correspondent, based in Mexico City.

13 January 2015 7:15 pm

It started with the best of intentions. When evidence emerged that monarch butterflies were losing the milkweed they depend on due to the spread of herbicide-resistant crops in the United States, people across the country took action, planting milkweed in their own gardens. But a new paper shows that well-meaning gardeners might actually be endangering the butterflies’ iconic migration to Mexico. That’s because people have been planting the wrong species of milkweed, thereby increasing the odds of monarchs becoming infected with a crippling parasite.

Habitat loss in both the United States and Mexico has long been the main threat to the North American monarch population. After decades of effort, Mexico curbed deforestation in the butterflies’ winter habitat in the oyamel fir and pine forests of Michoacán and Mexico states. But the loss of milkweed in the United States continues to be a major issue, scientists say. The plant, on which monarchs lay their eggs, used to spring up in between rows of corn, soybeans, and other commercial crops. But today, many farmers plant herbicide-resistant versions of these crops, which allows them to spray their fields with powerful chemicals such as Roundup—killing milkweed in the process. Last year, the number of monarchs that migrated to Mexico was the lowest ever recorded, covering a mere 0.67hectares of forest, down from a high of 21 hectares in the 1996 to 1997 season. (Scientists in Mexico are planning to announce this season’s count by the end of the month.)
That's why many monarch buffs swung into action. However, the only species of milkweed w
idely available in the United States is Asclepias curassavica, which is native to the tropics. Tropical milkweed is pretty, easy to grow, and monarchs love it. “If I were a gardener, I would have done the same thing,” says Dara Satterfield, a doctoral student in ecology at the University of Georgia, Athens.
The problem is that tropical milkweed—at least when planted in warm environments like southern Texas and the U.S. Gulf Coast—doesn’t die back in the winter like native milkweed does. When presented with a place to lay their eggs year-round, many monarchs don’t bother making the trip to Mexico at all. Tropical milkweed is “trapping the butterflies” in these new winter breeding sites, says Lincoln Brower, a monarch biologist at Sweet Briar College in Virginia.

But it turns out that year-round tropical milkweed presents an even more direct threat to the butterflies. Milkweed hosts a protozoan parasite called Ophryocystis elektroscirrha (OE). As caterpillars, monarchs ingest the parasite along with their normal milkweed meals, and when they hatch from their chrysalises they are covered in spores. “It’s a debilitating parasite,” Satterfield says. Infected monarchs are much weaker than their healthy counterparts and don’t live nearly as long. In fact, if an OE-infected monarch tries to migrate, it will probably die long before it arrives in central Mexico, Satterfield says.

In that way, the migration is vital to keeping OE under control in the North American monarch population, Satterfield explains. Migrating “weeds out some of the sick monarchs every year,” preventing them from passing the parasite along to their offspring. What’s more, it gives the monarchs a chance to leave behind contaminated milkweed plants, which then die off during the winter. When the butterflies return in the spring “they start over fresh” with new, clean milkweed, Satterfield says. But if the monarchs aren’t migrating, and the tropical milkweed isn’t dying off, OE never goes away.

To figure out if tropical milkweed is increasing OE infections among monarchs, Satterfield enlisted scientists and volunteers to help her sample thousands of butterflies at breeding sites in the United States, as well as in their winter habitat in Mexico. The technique is easy to learn and, with a light touch, harmless: Simply press a small piece of transparent tape against a monarch’s abdomen to collect any OE spores and then send the tape to Satterfield’s lab. She and her colleagues then counted the number of spores trapped by the tape to tally infection rates at different sites. Monarchs who stayed in the southern United States for the winter were five to nine times more likely to be infected with OE than migrating butterflies were, the team reports online today in the Proceedings of the Royal Society B. In some winter breeding sites, 100% of monarchs they sampled were infected, Satterfield says.

The work proves “absolutely definitively” that tropical milkweed is threatening the monarchs and their migration, Brower says. And the findings are particularly troubling for monarchs returning from Mexico in the spring, he adds. They pass right through these winter breeding sites and could lay eggs on infected milkweed while they are there or mate with infected butterflies. Infecting the returning monarchs with OE “is the last thing we want to do, particularly when the monarchs are in the low numbers that they are now,” Brower says.

Satterfield’s study “quantifies something we knew was a risk,” says Karen Oberhauser, a conservation biologist at the University of Minnesota, Twin Cities. And it’s hitting the monarchs at a particularly vulnerable moment. If the North American population were bigger, the number of winter-breeding, OE-infected butterflies would be trivial compared with the number of hearty monarchs migrating to Mexico. But as the population shrinks, risks like OE can have an outsized effect on overall population numbers, Oberhauser explains. The U.S. Fish and Wildlife Service is now reviewing the monarch’s status under the Endangered Species Act.

There is some good news. Nearly all tropical milkweed in the southern United States is in gardens, Oberhauser says. So if everyone who planted it to help the butterflies can be convinced to replace it with a native milkweed species—or at least cut the plant back every few weeks during the winter—they could quickly put a stop to the destructive winter-breeding trend. (Native milkweed isn’t always as easy to get as tropical milkweed, but it’s starting to become more available online, Satterfield reports.) According to Oberhauser, tropical milkweed is “a problem we can solve.”

Seaside gentian plant on Palm Island

Seaside gentian Eustoma exaltatum Palm Island 1.15.15

During a walk around the northern tip of Palm Island today I came across a seaside gentian, Eustoma exaltatum, in flower which I never recall having seen before.

A remarkably beautiful plant in a harsh salty setting behind the beach dunes.

Has anyone else encountered this species and if so where?


Natural Encounters During Winter in SW Florida‏

Sea hares breeding in Bocilla Lagoon
Although SW FL gets its share of cooler weather with strong northerly winds during periodic cold fronts, there can be warm interludes during which many animals are quite active and even breed.  One of my favorite signs of winter is the breeding of the ragged sea hare, a mollusc lacking any external shell.  This picture was taken on Dec. 20.  Sea hares are hermaphroditic and can act both as male and female in breeding balls or lines, resulting in chains of greenish eggs.  The adults die shortly afterward but the planktonic larvae grow rapidly and metamorphose into tiny sea hares in about 3 weeks.  The adults are protected by their disruptive coloring and shape and by toxins in part derived from their algal food; the ink they expel in response to disturbance appears also to be toxic and anti-bacterial.  

Thorn bugs on powder puff plant
We recently planted a powder puff plant and soon discovered some interesting insect pests on it.  These thorn bugs have an amazing shape to protect themselves from predators- they mimic a thorn and stay in groups and can be surprisingly difficult to spot.  I have seen them also on wild blackbead plants in considerable numbers.  They can damage plants by sucking out sap and by piercing the bark during egg laying.  The female on the left has a pointed spine and the male on the right a flattened spine.  They are protected by a toxin and the honeydew they secrete can lead to mold formation.  So despite being a very beautiful insect they are not something you want to keep around in large numbers!

Nursery pipevine with polydamas butterfly caterpillar
If you have planted exotic pipevines you will likely find some polydamas butterfly caterpillars on it someday.  Although pipevines have a remarkable flower they are usually planted to attract butterflies so the caterpillars are not considered pests when they eat the vine.  You may want to manage your herd of caterpillars by moving some elsewhere if the vine is nearing obliteration. 

Pipevine swallowtail caterpillar on wild pipevine
Further north a common caterpillar on pipevines would be the pipevine swallowtail, and I have shown an example from Virginia.  They are very scarce in our area of Florida perhaps since the native pipevine is quite small.  Can you tell the cats apart?  Note that the polydamas has a yellow ring behind its head but otherwise they are quite similar as befits their close relationship.  Both show a warning coloration which reflects their toxicity due to poisons obtained from their pipevine food.

Peninsula cooter turtle: female "hairpins" on top of head
An interesting observation I made while driving was encountering a large female peninsula cooter turtle crossing the road.  The females are often seen in winter when they come up on land to lay their eggs, but this individual allowed me to photograph the top of her head.  The pattern there, a central "arrow" with two "hairpin"-shaped loops just behind is a primary means of distinguishing this species from the red bellied and chicken turtles.  But of course turtles pull their head into the shell when threatened so you often cannot see this pattern. 

Litle blue heron foraging in FL yard
It is common to see white ibis and great egrets in our yard foraging for lizards and insects. But I was surprised to see this little blue heron engaging in yard foraging recently on two occasions.  The ability of birds to flourish along with human civilization often depends on their flexibility in adapting to new feeding possibilities. Thus I was pleased to see this little blue learning some new tricks which will likely improve its reproductive success.  I think it may have adopted this terrestrial foraging mode in yards from accompanying white ibis flocks and observing their habits. Such mixed species feeding aggregations of wading birds are common in aquatic habitats but less so on land.  So watch for this behavior in your area and see what patterns are occurring.

Male cardinal and yellow throated warbler share a bath
Another example in our yard of the attraction that a water drip/bath has on birds is this photo of an "odd couple" sharing one of our three baths.  A male cardinal and a yellow throated warbler seem quite happy to splash together and enjoy the soaking.  They are both regular visitors to our baths and I am happy to see them being willing to share the bath, which some species such as mockingbirds are not.  

Bald eagle over FL yard 1-6-15
While standing on our dock I noticed the usual ospreys and sea birds in flight, but the sudden appearance of this eagle sent the ospreys into a rage.  There is no love lost between these species since the eagle often steals fish from the ospreys.  This was an interesting bird since it is about six months shy of being a full adult.  Bald eagles pass through a series of four major plumages called basic 1 to 4.  So this bird has a yellow bill, a "dirty" head and tail, a black tail line, is still molting some feathers, and is thus a basic 4+.   It is fun to try to age the eagles you see by fitting them into one of the four plumage categories.

Moorhens on floating island pond at Wildflower Preserve
The common moorhen or gallinule has been a widespread Florida bird for many years but seems to be declining due to competition for food with the introduced African tilapia fish.  At Wildflower Preserve there have been breeding moorhens in some of ponds with the most nutrients and duckweed, but the lack of cover around the edges is a limitation of the habitat. 

So when floating islands were introduced into one pond it was exciting to see that  the moorhens used them for breeding (those with growing plants in them) and just for hanging out on this island that has fewer plants.  The original purpose of these plant islands was to remove excess nutrients from the water but the unanticipated benefit to moorhens and other animals has far exceeded the original purpose.  

Yellow crowned night heron
The yellow crowned night heron is the common inhabitant of the mangrove fringe in our yard and we often see them resting or foraging for crabs.  They are the characteristic mangrove wading bird in higher salinity waters whereas the black crowned night heron is found primarily in low salinity areas.  One of the main differences between them in addition to the colors of the adults is the size and color of the beak.  This photo shows how the yellow crowned has a very strong beak, the better to crack crabs, and it is all dark colored.  The black crowned has a narrower beak which is usually partly light colored.  

So enjoy nature wherever you find yourself in winter, but if you are in Florida you may expect a wide variety of animal activities to continue, alternating with the strong seasonal shifts in temperature due to frequent cold fronts that pass over the state.

Bill Dunson
Englewood, FL and Galax, VA

Monday, January 5, 2015

A night heron thinks about swimming?

I happened to notice that an adult yellow crowned night heron, which normally spends time in our mangroves hunting crabs, was standing on the side of my neighbor's pool in SW FL.  It seemed to be gazing deeply into the water and I wondered what it might be thinking. 

Since this is a bird that only wades in water and does not swim to my knowledge, I doubt that it was contemplating a swim.  Maybe it was fascinated by its reflection in the water and perhaps viewed this image as a rival?
In any case it was another of the myriad of interesting wildlife observations that can be made all around us.

     Bill Dunson

A picnic on the beach below Stump Pass and a rare bird‏

Anchored off the Spit at sunset

Just at sunset on Jan. 2, I was on the beach south of Stump Pass at the Spit, aka northern end of Knight/Palm Island.

A family of four (two parents and two small children) had anchored off the beach and had a picnic ashore complete with a table and chairs.  They were departing at sunset with some difficulty since the surf and the deep water make boarding a boat a wet experience.  They all made it and I am sure enjoyed their adventure.
Whimbrel with willets on Palm Island

There was to my surprise a very rare bird, a whimbrel, about 50 feet away with a group of willets.  It has been seen in the general area for several weeks but moves around between Stump Pass Beach State Park, Cedar Point and Palm Island.  A huge group of red knots, dunlins and other shorebirds was also settling down for the night nearby, illustrating how the beaches in the area can be utilized by large numbers of birds, especially in the late afternoon/evening.

Bill Dunson

Friday, January 2, 2015

An Arctic Snowbird Visits SW Florida‏

Sunset on Palm Island 12-24-2014
The variety of birds at the beach can be challenging but it is very rewarding not only to identify them but to learn about their habits.  The variation in migration patterns is quite astounding.  Some birds breed in SW FL but many migrate to distant regions.  I was recently at Palm/Knight Island at dusk to observe a large aggregation of birds.  There were the usual gulls and terns, many dunlins and skimmers, but of most interest was a large group of about 150 red knots.  

Red knot on the Spit
Our winter resident knots are dull gray in color, quite unlike their reddish plumage during the breeding season.  They are medium sized shorebirds, about 5 oz in weight, with an intermediate sized bill that they use to probe in sand for food. They breed in the high Arctic in tundra habitats near the ocean.  It appears that they fly to and from the Arctic via Delaware Bay, where they gain weight for their flights eating the eggs of horseshoe crabs.  Then they work their way down the east coast, eventually  reaching their wintering grounds in the Gulf of Mexico.   We know this itinerary in some detail due to the efforts of scientists who have marked the knots with leg tags.  One of the more exciting activities I have on the beach is to search for marked red knots.  I found one in the group on Palm Island which had a light green flag on its upper left leg marked 6C9; there was a silver metal band on the right leg.  I checked on the website  and found that this individual red knot was banded on Oct. 18, 2011, three years and two months ago in SC and subsequently re-sighted ten times in SC, GA and FL.  This small bird has thus made at least four flights to and from the Arctic Ocean, a very impressive feat.  Let's do what we can to protect these marvelous birds while they visit us.

Red Knot 6C9 on Palm Island
Bill Dunson 
Englewood, FL and Galax, VA