Thursday, February 28, 2013

Lounging lizards

I was not able to find any native frogs in the garden.  Consequently, it may be too late to help the native frog community by actively removing Cuban tree frogs (Osteopilus septentrionalis).  Yet, native frogs are not the only ones threatened by Cuban tree frogs.  Among the many other types of prey that Cuban tree frogs consume are lizards.  Nevertheless, despite the presence of several very large Cuban tree frogs, anoles were extremely abundant in the garden this winter. 

A Cuban brown anole (Anolis sagrei).
Unfortunately, the majority of these anoles belonged to another species introduced from Cuba: the Cuban brown anole (Anolis sagrei).  This anole has itself played a large role in displacing native anole species.  The second most common anole was also a non-native: the bark anole (Anolis distichus), which has been introduced to Florida from the Caribbean.

Another anole, probably a bark anole (Anolis distichus).
I did find one native species persisting: the Carolina anole (Anolis carolinensis).  However, this species was quite rare compared to the two introduced species pictured above.

A Carolina anole (Anolis carolinensis) on a palm frond.
Given this composition of the anole community, it is not clear to me whether removing Cuban tree frogs would improve or worsen the situation for the native anoles.  Removing the native anoles' predators might simply increase the number of their competitors.

Monday, February 25, 2013

They are only cute when they are young

Cuban tree frogs (Osteopilus septentrionalis) are commonly available as pets.  Yet, the ones that I encountered in the garden during the day were quite unattractive.  For a while, it was a mystery to me why anyone would want one of these frogs as a pet.  Then, I started to find juvenile Cuban tree frogs. 

A juvenile Cuban tree frog (Osteopilus septentrionalis) in a bromeliad at night.
The juvenile frogs appeared mostly in and around bromeliads, but only at night (except for the first one I saw).  Juvenile Cuban tree frogs are more difficult to identify unequivocally than are the adults, but by process of elimination, these frogs did not seem to belong to any of the native Florida species.

Another juvenile Cuban tree frog (Osteopilus septentrionalis) in a bromeliad at night.
With their smooth skin and large eyes, the appeal of these young frogs as potential pets is more understandable.  However, they do not keep their good looks forever and can continue to live in captivity for up to ten years.  Moreover, the mucus on their skin can cause irritation and allergic reactions if these frogs are handled.

Yet another young Cuban tree frog (Osteopilus septentrionalis) in a bromeliad at night.

Thus, despite their innocent youthful appearance, Cuban tree frogs do not make very good pets.  Furthermore, if no longer wanted pets are released, they may invade new habitats and disrupt native communities -- just as our backyard frog community was disrupted.  In the end, I was not able to find any frogs in the garden other than Cuban tree frogs.

Saturday, February 23, 2013

Frog in a hole

After finding a Cuban tree frog (Osteopilus septentrionalis) in the garden, I began a survey to determine whether there were any native frogs persisting.  Many frogs are nocturnal, but my daytime searches did reveal three large frogs. 

A Cuban tree frog (Osteopilus septentrionalis) in a rusted pipe.
I found these frogs in sheltered nooks around the exterior of the house.  Once I had located their hiding spots, I could reliably find the same frogs day after day.  However, being able to see the frogs on a daily basis was not very comforting, since they were all Cuban tree frogs.

A Cuban tree frog (Osteopilus septentrionalis) in an exhaust vent.
At night, these frogs would emerge from their daytime retreats.  Sometimes I would see them nearby (such as the frog pictured below, which would spend the day tucked between the duct and the wall), while other times I would simply find their usual spots temporarily vacant.

A Cuban tree frog (Osteopilus septentrionalis) near its refuge in the evening.
The large frogs were coming out of hiding in order to hunt, and so too were many smaller frogs.  To be continued...

Wednesday, February 20, 2013

Cuban tree frog crisis

On my very first morning back in Florida, I encountered not only sea gulls and a snake, but also a small frog sitting in a bromeliad.

A tree frog in a bromeliad.
My excitement at finding the frog did not last long.  Although there are several tree frog species native to Florida, this frog did not belong to any of them.  It was a Cuban tree frog (Osteopilus septentrionalis), a member of an introduced species that is known to outcompete and even to eat native frogs.  Cast in this light, the frog quickly shifted in my view from a welcome resident of the garden to an imposing villain.

A Cuban tree frog (Osteopilus septentrionalis) in a bromeliad.
Nevertheless, Cuban tree frogs also eat insects, including some pests.  Thus, they may provide an important service in the garden.  We were left with a dilemma: should we catch and euthanize these introduced frogs (as has been recommended by some), or leave them alone?  We decided that the answer to this question depended on others: What was likely to happen if we did manage to cull the Cuban tree frog population in the garden?  Would any native frogs return?  I read a couple of anecdotes that suggested removing Cuban tree frogs would result in increases in native frogs.  However, would the same happen deep within the invaded range?  Were there any other frogs left in the garden that could benefit from the removal of the Cuban tree frogs?  To be continued...

Explore some more: Invasive Cuban Treefrogs in Florida; The Cuban Treefrog in Florida

Monday, February 18, 2013

Long live the queen butterfly

Although one encounter with a parasitoid wasp ended without incident, the queen caterpillars (Danaus gilippus) were not out of danger.  As I was looking over my pictures from the previous day, I noticed another wasp -- sitting on top of the largest of the queen caterpillars.

A queen caterpillar (Danaus gilippus) and a parasitoid wasp.
If you have trouble finding the wasp in the picture above, look between the 5th and 6th yellow stripes from the left, or just look at the close-up below.

A close-up of the parasitoid wasp on the queen caterpillar.
In the subsequent pictures that I took (which unfortunately are not focused on the wasp), the wasp's abdomen is curved down and the wasp appears to be ovipositing (laying eggs) into the caterpillar.  After inspecting this series of pictures, I decided to monitor the caterpillar closely for any sign that it was indeed parasitized.  However, the next morning, the caterpillar had disappeared from the milkweed.  By searching the surrounding area, I eventually located the caterpillar in a sheltered spot where it was beginning its transformation into a pupa.

The queen caterpillar preparing to pupate.
One day later, there was a very healthy-looking chrysalis where the caterpillar had been.

The chrysalis of the parasitized(?) queen caterpillar.
Over the next few days, the chrysalis continued to look as it should, without any dark discoloration to suggest that there were a couple hundred wasps developing inside instead of a butterfly.  I left Florida before I could be sure what the result would be, but I have been informed that in the end the wasp's attempt failed and it was a butterfly that emerged from the chrysalis.

This is a different queen butterfly (Danaus gilippus), since I didn't get to see the one that emerged from the chrysalis.

Friday, February 15, 2013

Royal parasite

Many plants protect themselves from herbivory with toxic chemicals.  However, some herbivores not only tolerate these compounds, but also actively sequester them to become distasteful themselves.  For example, caterpillars such as monarchs (Danaus plexippus) and queens (Danaus gilippus) prefer to feed on milkweeds, which contain toxic cardiac glycosides.  Nevertheless, this dangerous diet does not deter all the caterpillars' potential enemies.  One day when I went to check on the caterpillars, I found a parasitoid wasp roaming the milkweed plant.

A parasitoid wasp on a milkweed stem.
With its antennae twitching up and down, the wasp walked along the milkweed stem...

The wasp walking along a stem above a queen caterpillar.
...and gradually closed in on one of the queen caterpillars.

The wasp perched directly above the queen caterpillar.
When the wasp reached the end of the stem, it appeared poised to descend and parasitize the caterpillar.  Yet, anticlimactically, the wasp flew off and the caterpillar continued eating the milkweed in peace.

Thursday, February 14, 2013

My Valentine bee

Many millions of roses have been cut for Valentine's Day, but I much prefer my roses uncut -- and, of course, full of insects and spiders.  So, here is a bright red Valentine's rose for all my readers, complete with a metallic green bee!

A metallic green bee (Agapostemon sp.) in a red rose.

Tuesday, February 12, 2013

Not quite a lady-killer

During the day, the most numerous visitors to the flowers in our garden in Florida were not bees, butterflies, moths, flies, or, indeed, anything flying.  Instead, the flowers were occupied by foraging ants.  While I watched, these ants were never interrupted by any competitor for the flowers' nectar or pollen.  An incident I observed one evening suggested why the ants were left to benefit alone, by demonstrating how aggressively the ants could defend their chosen flowers from trespassers.  As I walked through the garden, my flashlight revealed a cactus lady beetle (Chilocorus cacti) on a Pentas sp. flower.  At that same moment, the lady beetle was being inspected by an ant.

An ant inspects a cactus lady beetle (Chilocorus cacti) on a Pentas sp. flower.
The ant approached more closely, and very soon after they came into contact, the ant closed its mandibles around the lady beetle's exposed wing.

The ant holding onto the lady beetle's wing.
Though the lady beetle dragged the ant across several flowers, for some time it was not able to escape.  If there had been more ants in the vicinity, the lady beetle might have been in some danger of being overwhelmed. 

The lady beetle tries to crawl away, but is held back by the ant.
As it was, the lady beetle eventually pulled loose, and without any apparent damage to its wing.  Once free, the lady beetle made its quick departure from the flowers.

Friday, February 8, 2013

No sting in the tail

When I first moved to Arizona several years ago, I was more concerned about scorpions sneaking into my second floor apartment than was altogether rational, and each morning I would check my shoes to make sure that no scorpion had crawled inside during the night.  Arizona was not so full of scorpions, however, that any ever took refuge in my shoes or anywhere else in my apartment.  In fact, I only encountered scorpions when I looked specifically for them in the desert at night and when I searched under rocks during the day.  Surprisingly, a scorpion (of sorts) was to be found much closer to home in Florida.

A short-tailed whipscorpion (Schizomida: Hubbardiidae) that I found under a rock.
I was looking under rocks just outside the house when I found something that looked like an odd spider.  I did not think much about it at the time, since it was so small and quickly disappeared into the loose soil.  However, once I looked at the magnified picture, I realized that its shape was not right for a spider, and I was eventually able to identify it as a short-tailed whipscorpion.  Despite the intimidating name, the members of this unusual group are not particularly closely related to scorpions and lack the long tail and stinger.  They also lack eyes.  Instead, they use their front pair of legs to feel their way as they walk along on their other three pairs of legs.

Wednesday, February 6, 2013

I hear a rat

While I was in Florida, I witnessed a very different midwinter's feast than that enjoyed by the flocks of birds here in Eastern Washington.  There, the fare was a bounty of bright red fruits, freshly ripened on the Christmas palms (Adonidia merrillii).

Ripe fruits of a Christmas palm (Adonidia merrillii).
However, during the day, these fruits did not seem to attract any attention from consumers.  It was only at night, while I was out searching for frogs, that I heard noises coming from the vicinity of the fruits.  Looking up, I caught a brief glimpse of a furry body as it scrambled away through the canopy.  I thought it might have been an opossum, since we had seen them in the yard in previous years.  The next night, I spooked the creature again before I could get a better look.  Finally, on the third night, I approached the trees more cautiously -- and saw that the creature was definitely not an opossum.

* To see this video in high definition (1080p), you may need to (1) click "YouTube" to watch on the YouTube website and (2) change the settings at the bottom of the video screen.

The creature that had been feasting on the palm fruits each night was a rat.  Although the poor lighting makes it difficult to see many distinguishing features, the rat looks (at least to me) more like an Eastern Woodrat (Neotoma floridana) than any of the other rodents listed as living in Florida.  The only problem is that the species is thought to be locally extinct this far south in the state!

Monday, February 4, 2013

Tracing the thin green line

This weekend, I decided to spend some time adding new insects and spiders to my online photo collection.  I was searching for information on one of my new entries, the spinybacked orbweaver spider (Gasteracantha cancriformis), when I stumbled upon pictures of a very familiar object: a yellow oval intersected by a green line.

The egg sac of a spinybacked orbweaver spider (Gasteracantha cancriformis).
I had seen three of these objects in our garden in Florida but had been unable to identify them.  Now, at last, I have my answer -- they were the egg sacs of spinybacked orbweaver spiders. 

Female spinybacked orbweavers produce egg sacs in the fall and winter.  Though the eggs hatch after only a couple of weeks, the spiderlings may remain inside the egg sac for several more weeks before emerging.  Thus, the egg sacs that I saw might still have been full of spiderlings.  In several months, if all goes well for the spiderlings, the females will look like this:

A female spinybacked orbweaver spider (Gasteracantha cancriformis) in the center of its web.
Although the mystery of what was hidden beneath the green line has been solved, I have not yet found any explanation of why the egg sacs are marked with a distinct green line.  There seems to have been more interest in why the webs of this species contain tufts of silk (see the picture above).  One idea is that they are a signal to birds, to prevent them from accidentally flying into the webs.

Saturday, February 2, 2013

Is spring coming early?

Even though it is not yet Groundhog Day, there have been signs that spring is coming early.  For the past few days, the weather has been sunnier and warmer (i.e., above freezing).  As a result, almost all the snow has melted -- revealing not only the ground, but also the bright green leaf tips of a multitude of bulbs.

New daffodil shoots pushing up through the ground.
The birds are also taking advantage of the turn in the weather.  This morning, I was alerted to the return of some migrants by the unexpected sound of loud honking; I looked out the window just in time to see a flock of Canada geese (Branta canadensis) flying from the south.  Meanwhile, birds that have been enduring the winter here now have expanded food options.  Many of the Cedar waxwings (Bombycilla cedrorum) have switched their diet from juniper berries to the freshly uncovered cotoneaster berries, and a small flock of dark-eyed juncos (Junco hyemalis) has been busy hopping  around and pecking at various small items that had been hidden underneath the snow.

A male dark-eyed junco (Junco hyemalis, "Oregon" subspecies) foraging on the ground.