Snakes ‘starving’ because of shortage of frogs to eat

Mass die-off of amphibians taking toll on their predators, biologists find

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Snakes have been ”starving” to death after a mass die-off of forest frogs deprived them of their unusual meal, scientists have discovered.

More than 500 frog species in central America have declined in numbers, including 90 that have gone extinct since 1998, biologists said. In 2004, a fungal pathogen outbreak caused a mass die-off.

In the following years, numbers of snakes and the variety of species plummeted, found researchers from the University of Maryland and Michigan State University.

“Comparing the after with the before, there was a huge shift in the snake community,” said Karen Lips, a professor of biology and co-author of the study.

“The community became more homogeneous. The number of species declined, with many species going down in their occurrence rates, while a few species increased.

“Body condition of many snakes was also worse right after the frog decline. Many were thinner, and it looked like they were starving.”

Many snakes rely on frogs and the amphibians' eggs as part of their diet.

The study, published in the journal Science, compared seven years of data collected in a national park in Panama before the outbreak of the pathogen chytrid, with six years of survey data afterwards.

The academics cannot say exactly how many snake species declined because sightings are rare, but they are sure the drop was caused by the loss of amphibians, not other environmental factors. The park is protected from habitat loss, development and pollution.

The researchers said their findings would be important for conservation studies.

“This work emphasises the importance of long-term studies to our understanding of the invisible, cascading effects of species extinctions,” Prof Lips said. “Everything we watched changed after the frogs declined. We have to know what we are losing, or we run the risk of undermining effective conservation.”