Brown Treesnakes - 10 of 15

Brown Treesnakes FAQs - 15 Found

Why don't you introduce a predator to simply eat all of the brown Treesnakes (particularly the mongoose or kingsnake)?

This is probably the most frequently asked question regarding the brown Treesnake.  It seems like a simple and obvious solution; however, the many ecological concerns and implications accompanying such a move illustrate the dangers of this tactic.  While introducing predators has been attempted in many situations across the world, it has more often than not met with disastrous results.  Introducing the mongoose has been attempted for controlling snakes and rats on islands (e.g., in Japan and the Caribbean), but mongoose were found to commonly feed on nontarget species as well as snakes and, while the snake and rat populations continued to proliferate, the more vulnerable nontarget species suffered greatly.

As is the case with the mongoose, the kingsnake does eat snakes, but does not include them exclusively in its diet.  Kingsnakes will eat other snakes, including rattlesnakes (they are immune to the venom), but they also eat lizards, frogs, birds and their eggs, and small mammals.  Many of these species (native birds and lizards, especially) are already severely depleted on Guam and are the focus of major conservation attempts at present.  Introducing another predator to further stress these struggling populations would cause an even greater crisis and would most likely be disastrous for these species.

A secondary issue regarding the kingsnake involves its habits and potential for effectively pursuing a brown Treesnake even if given the opportunity.  The kingsnake is not a climber (arboreal) like the brown Treesnake.  Since brown Treesnakes spend the majority of their time in trees and can climb all but extremely smooth surfaces, pursuit would be difficult for terrestrial kingsnakes.  Also, brown Treesnakes are generally between 3 and 6 feet, but have been found primarily in urban areas with lengths of 8-11 feet! This would be a challenging meal for a kingsnake, ranging in length from 30 to 50 inches (2.5-4 feet) and a maximum of about 5 feet.

Some have also suggested that a nicely matched predator might be a hawk, owl, or roadrunner.  Again, these birds have very specific habitat needs and would find Guam lacking in these areas.  While some birds do indeed prey on snakes, including the short-toed bald eagle (Circaetus gallicus) which is probably the only bird that strictly feeds on snakes, they also require large habitat of forested areas--habitat that is limited on Guam.  Also, many birds would be vulnerable to predation by the snakes on their eggs, as are the native and introduced species of birds on Guam.

Other specific suggestions have been made, but the bottom line is that introducing a predator to control another species rarely works the way it is envisioned.  Often, these introduced species cause damage to unrelated species that become prey.  They may also have negative impacts on indigenous plants, have the ability to bring with them mites or other parasitic organisms that can affect newly exposed wildlife, and may in the end fail to control the one intended species while introducing other long-term effects of their own. While some animals on Guam, including monitor lizards and feral pigs, are known to eat brown Treesnakes opportunistically, they don't seem to prefer the tough snake and have not caused any noticeable decline in snake numbers.  Even humans have reported that these snakes taste bad!  Yet an enterprising few have attempted to create appetizing snake dishes.  While these recipes have found a limited audience, the occasional backyard barbecue or gourmet use of snake meat has had no effect on snake population levels.

Tags: Ecosystems, Biodiversity, Endangered Species, Reptiles, Snakes, Predator, Constrictors