Hungry snakes hunt bird eggs

I

nvasive species are a pain in the gluteus maximus, and the Burmese pythons are no exception. Like poor and desperate college students, these voracious snakes will do almost anything for food. With this insatiable appetite, they have decimated most of the mammal populations in the Florida Everglades and now have their eyes on the birds.

These 16 foot-long reptiles are not the type to sit and wait for birds that are unfortunate enough to cross their line of sight. Like the cunning cuckoo, they seek out the homes of birds and snatch their eggs straight from the nest. Study researcher Carla Dove of the Smithsonian Museum of Natural History says that although the sample size is small, the findings suggest that the snakes could pose a threat to the breeding success of native birds.

The snakes, originally native to Southern Asia, were detected in 2000, when rangers removed two snakes from the swampland. Since then, the python population has exploded, with more than 300 snakes being removed from the Everglades ever year since 2007. The origin of this invasion, scientists suspect, are people who kept these snakes as household pets.

Relatively speaking, the pythons are one of the newer additions to the hall of invasive species. Famous examples include zebra mussels and kudzu, a Japanese vine that smothers native plants in their leafy embrace. These invasive species tend to thrive in environments similar to their own. Except in the absence of strong predators and competitors, they become the supreme rulers of the land.

Good invaders tend to have evolutionary traits that would make them very successful even in their native environments. They tend to breed explosively, can eat almost everything they see, and can easily adapt to different situations. Sounds a lot like us, doesn't it? Of course, not all invaders are not leafy, slimy creatures - Australia, for instance, is currently dealing with a plague of cute and cuddly rabbits.

Like most invasive species, the pythons are living the life in their new environment. The native animals, having never evolved defenses against these eating machines, are easy kills for the snakes. With no predators to stand against the pythons, the local mammals and vegetation have essentially become a giant buffet. Unfortunately, the pythons just love spreading their seed - researchers estimate that at least tens of thousands of them have infiltrated the National Everglades Park.

To better understand the opportunistic invaders, the researchers monitored the python's diet by probing the contents of their stomachs. In a previous study of 300 captured snakes, they found that about 25 percent of the python's diet was composed of more than 25 species of birds. Talk about a diverse diet!

In the latest study, researchers found proof that the snakes were terrorizing nests. In their stomach-churning study, they found whole eggs in the stomachs of three specimens. Most snakes evolve adaptations that enable them to pierce eggshells, but the python's large size and preference for small eggs allows them to swallow them whole. Think of it as the difference between swallowing a tiny gumball and chewing on a jawbreaker.

The three specimens in this study include a 14-pound male python about 8.5 feet in length, which was acquired near a house in Florida's Miami-Dade County. The snake regurgitated 10 guinea fowl eggs soon after his capture, all of them intact. In addition, the team found the remains of two more eggs in a 30-pound female python, with a length of over 10 feet.

The researchers analyzed shell fragments from the crushed bird eggs and compared them with intact samples from the Smithsonian collection. The victims turned out to be from a bird called a limpkin, a large marsh bird that is listed as a "species of special concern" by the Florida Fish and Wildlife Conservation Commission.

According to their observations, the invasive pythons are snacking on both adult birds and eggs. This represents the first known instance of an invasive species preying on nesting birds. Given our history of importing exotic animals, it probably will not be the last. While there may be almost no limits to what pets one can keep, hopefully at least no one will be naive enough to introduce any nasty piranhas to our poor, defenseless lakes.