Tuesday, June 28, 2011

Buffet Mixer

There are a variety of benefits to doing things in groups. Consider the last cookout you attended. Someone else bought the food. Someone else cooked and cleaned up. There was less risk of being eaten by a predator. Communal roosting makes sense too. Eating and roosting together makes sense for Great Egrets, Snowy Egrets and White Ibis.

More ears and eyes means predators are at a disadvantage during a sneak attack. While roosting, huddling can conserve warmth for those with the best spots in the roost. The downside is when you head out for breakfast in the morning everyone follows. The older and experienced birds tolerate social parasitism in exchange for safety in numbers. There is a pecking order and bigger birds can dominate others in the flock.

Finding food is also easier with many eyes looking. Once located, the buffet commences. Here a flock of Great White Egrets, Snowy Egrets and a few White Ibis have found a high concentration of fish and frog eggs to feast on.

Around the outskirts of the buffet are Little Blue Herons who are exhibiting commensalism. As the Egrets and Ibis stir things up, the Little Blue Herons feed on what the rest of the birds are not interested in. Essentially commensalism is when one species feeds among others and benefits without harming or benefiting the main species. In this case the Little Blue Heron is the guy that came to the party with the friend you invited. Little Blues are twice as successful when feeding commensally as opposed to individually.

May marked the end of the dry season in Florida which generally runs from December through May 15th. As the wetlands begin to fill with water and prey species re-colonize the marshes and swamps, many of the wading birds will rely less on communal feeding and venture out to forage solo. After a long day of hunting, it’s back to the communal roost for an evening of preening and sleep. Party on.

Sunday, June 26, 2011

Murder in the Marsh - The Florida Sandhill Crane

“Someone just shot a Sandhill Crane in the marsh” I said with disgust. “Is that bad” a friend asked.

Yes that’s bad.

A)    The Florida Sandhill Crane (Grus canadensis pratensis), is listed as Endangered in Florida due to habitat loss and over hunting.
B)    Hunting of Sandhill Cranes is no longer permitted in Florida.
C)    The marsh where it was shot is off limits to hunting.
D)    The marsh where it was shot is within 300 yards of an elementary school
E)     I had just been riding my bike within the range of the shooter.

While a third of the Sandhill Crane population breeds in Canada and Alaska, the Florida subspecies is non-migratory and adults are rearing chicks right now. The marsh I visited has no less than four pairs of adult Sandhill Cranes. Presently at least two of those pairs have several week old chicks. Adults form long-term pair bonds and tend to their young for up to ten months. The marsh is ideal in that the cranes create a nest of debris and vegetation surrounded by water. They feed on insects, small vertebrates, like frogs and snakes and even they also eat seeds and fruits.

The marsh is a manmade stormwater filtration wetland but considering Sandhills lost most of their wetland habitat to drainage and suffered a subsequent population decline, they’ll take what they can get. What they don’t need is a random knuckle dragger using protected birds for target practice.

As my brother-in-law and I made our way towards the exit of the marsh trail, a shot rang out ahead of us. And another. The shooter turned, with rifle drawn on us, turned back to the Sandhill and fired. The bird went down with a wing flapping. Ibis, Anhingas, Herons and Sandhills joined a frenzy of squawks as they ascended and descended on the injured bird. I expected them to fly away but they were as traumatized as we were and seemed to be rallying around the wounded bird. One final shot and the adult bird was gone.

We raced home and called the sheriff, who was dispatched immediately. The shooter left before he arrived, but the single parent, mother of two Sandhill Crane fledglings remained. 

Friday, June 24, 2011

Sand Trapped - The Big Cypress Fox Squirrel

People don’t appreciate squirrels. One person’s pest is another person’s treasure. Such was the case as I drove past a golf course on my way out of a gated community in Fort Myers. Bounding across the fairway was a large Big Cypress Fox Squirrel (BCFS). I slammed on the brakes and jumped out, camera in hand. The tan-bellied, salt-and-pepper backed squirrel was as interested in me as I was of it and we stood for a moment like two gunslingers, unflinching. A disgusted woman shook her head and headed after her ball.

The Big Cypress Fox Squirrel (Sciurus nigra avicennia), is an endemic subspecies here in southwest Florida. They’re found from the Caloosahatchee south through the mangroves along the Gulf of Mexico. Unlike most of Florida’s terrestrial mammals, the BCFS are diurnal (day active), ground foragers. They feed on pine and cypress cones, palmetto berries, bromeliad seeds and a host of other native seeds and fruits. They prefer an open understory in the pine flatwoods, cypress swamps and mangroves. What is unusual is that as development continues to slice up their habitat, leaving it more and more fragmented, the squirrels have taken to golf courses which retain characteristics of their preferred habitat – open grazing areas with forested refuges.
Golf course BCFS have been shown to be more gregarious. They mate year round and are less susceptible to food shortages. Land managers have helped protect the species by leaving natural vegetation and planting trees, shrubs and grasses around the golf courses that specifically benefit the BCFS. The problem is sustainability. Increasingly these squirrel-occupied urban islands become more separated from natural communities and any link to other populations requires hazardous and often fatal road crossings.

Additionally, foraging around a golf course may seem like the life of leisure but without the protection of a forest canopy the squirrels must keep an eye skyward for birds of prey.

Their relaxed social standards could put them at risk as well. Normally solitary, golf course squirrels that congregate are at greater risk of spreading diseases to one another like Squirrel Poxvirus. A BCFS was found to be infected in 2010 and although an outbreak has not been reported, the virus is spread by contact and would have the greatest impact on sociable squirrels.

Golf courses have benefited BCFS to a degree but ultimately these populations must remain connected to their backwoods neighbors or they are all doomed. Will anyone miss them when they’re gone? 

Friday, June 10, 2011

Distracted–the Polyphemus Moth

I’ll be honest. I was just playing Angry Birds, the horribly addictive app I can play on my iPhone. It’s right next to Audubon Nature Florida. I’m supposed to be writing about a moth. I had intended to simply look up the scientific name for the moth in question on the Audubon app. No I don’t know all of the scientific names of every plant and animal. Gorilla is easy. But in doing that quick bit of research my attention was drawn to the small square box on my shiny smartphone housing an angry cardinal. The next think I know I’m launching ferocious birds at pigs. I’m ashamed.

The Polyphemus Moth (Antheraea polyphemus) lives and dies by behavior such as mine. The massive, night-flying member of the Saturniidae family of moths is decorated to both blend in among the leaf litter and confuse would-be predators with flashy eye spots. The six-inch wide, heavy-bodied moth has a week to live as an adult. There’s no time to feed. Females cast off an enticing pheromone that the males pick up on with their large, feather-like antennae. The males mate with multiple females while the females mate and go about finding a safe spot to lay their eggs.
At rest the tan, scalloped wing margins look like leaves and the insect can simply camouflage with its surroundings. At risk of being preyed upon, the Polyphemus Moth can flash the hind wings, unveiling two massive eye-like spots that give the appearance of something looking back. The wings are folded back in. The eye spots disappear and a confused predator either weighs the possibility of a challenge from another predator or can no longer find the thing with the bright flashy colorful spots that it wanted to eat.
Those familiar with Greek mythology might recognize Polyphemus as the one-eyed son of Poseidon and thus the naming of this beauty of a moth, which got me wondering why they named the movie the Poseidon Adventure. Back to the internet and long story short, Ernest Borgnine is still alive. Ugh. Now I need to research why the Angry Birds don’t have wings.