[bcbirdclub] Natural Encounters During Winter in SW Florida

  • From: wdunson@xxxxxxxxxxx
  • To: wad4@xxxxxxx
  • Date: Mon, 12 Jan 2015 18:13:33 +0000 (UTC)

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. 

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! 

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. 
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. 

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 
"hairpins 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. 

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. 

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. 

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. 

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. 

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 
http://lemonbayconservancy.org/news-blog/nature-notes-by-bill-dunson/ 






Attachment: Sea hares breeding Bocilla lagoon 12.20.14 Bill Dunson IMG_4313 aa.jpg
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Attachment: Thorn bugs on powderpuff plant 12.26.14 FL yard Bill Dunson IMG_4401 aa.jpg
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Attachment: Pipevine feeding cat polydamas sswallowtail on nursery vine 12.20.14 Bill Dunson IMG_4237 aa.jpg
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Attachment: pipevine swallowtail.caterpillar.comers.rock.rd VA on wild pipevine Bill Dunson.jpg
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Attachment: Peninsula cooter female hairpins on top head near Crowley Nursery 12.27.14 Bill Dunson IMG_4441 bb.jpg
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Attachment: Little blue heron forages in FL yard 1.1.15 Bill Dunson IMG_4483 aa.jpg
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Attachment: Cardinal and yellow throated warbler share their bath FL yard 1.1.15 Bill Dunson IMG_4463 aa.jpg
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Attachment: Bald eagle over FL yard 1.6.15 Bill Dunson IMG_4568 aa.jpg
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Attachment: Moorhens on floating island pond one WF 1.4.15 Bill Dunson IMG_4535 aa.jpg
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Attachment: Yellow crowned night heron adult head 1.2.15 Bill Dunson IMG_4475 bb.jpg
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