Campgrounds, sport fields, parks and resorts are just a few examples of human influences on natural areas. Human interactions like these tend to have a negative effect on the ecosystems around them by destroying habitats, changing food patterns and introducing new organisms. However, a new study posted in the Journal of Biological Conversation shows that the effects from human influences may actually be able to help endangered species and assist them in returning to natural numbers. Could tourisms really be used not only for a profit, but also for a means of natural conservation?
Scientists from McGill University and the University of West Indies came together to study this idea on the beaches in Barbados. In the 1800’s a small Asian mongoose was introduced to Barbados to help control rats. Like many other cases in history the mongoose thrived and still lives in relatively large numbers. However, today the mongoose threatens a new creature – the hawksbill sea turtle. Sea turtles lay their eggs on beaches, including Bath (beach in Barbados where testing was done), which are easy prey for many animals, especially the mongoose. Even though Bath is a highly active beach and tourist site, mongoose can easily prey on the eggs. Consequently, the sea turtles’ main predator is the mongoose and the sea turtle has now become an endangered species.
(Asian mongoose)
Between April and September 2005 scientists monitored the human and mongoose activity on the beach. On the beach they had 13 sites where ‘track pads’ were put in place. These track pads were areas of sand roped off where the tracks of mongoose were monitored. Every Sunday and Wednesday the pads were observed. On these days the track pads were checked three times – morning, afternoon and dusk - and observations were recorded. Mongoose tracks were cleared after they were monitored so new tracks could be seen later on. To record the morning tracks the pads were cleared the previous night.
Humans were recorded by two ways. When the pads were checked during the day a head count on humans was also conducted for a 50 m radius from the pad. Scientists also wanted an average number of how many visitors were at the beach on the observation days. They did this by counting the number of cars in the parking lot and assuming that they were at full occupancy. Vehicles were always assumed to be full not just because it was easier for the researchers but also because observations suggested they were usually full. This assumption only resulted in a less than 1% variation in population.
Not only were the mongoose and human population recorded but the availability of sea turtle eggs were also recorded. This was done by a beach survey and a visual observation. If the eggs were not hatched yet or preyed on, then they were considered an available nest. The nests were also repeatedly checked to see if the mongoose had tampered with them. If the eggs or eggshells were visible or a hole was dug, then the nest was considered to be preyed on by the mongoose. Without any interference by humans, mongoose attacks on nests result in a 100% mortality rate.
The results were that human variation on the beach has the capability to significantly change the mortality rate in nesting sea turtles. Although many people would and have expected this result, this study is believed to be the first with sufficient information. The scientists observed that the numbers of humans on the beach significantly changed the hunting area of the mongoose. The mongoose would avoid nests where human interaction was most likely even if it was where the eggs were. Most mongooses moved to dense vegetation although over 50% of the sea turtle eggs were found close to no vegetation. Scientists are calling this the “scarecrow effect”, implying that us [humans], are acting like a scarecrow and scaring away the mongooses.
Many people are saying that this could be the key to the sea turtle recovery. Although turtles face huge obstacles in all stages of life, the damage being done to nests can have long term and irreversible effects. The ‘human scarecrow’ idea is a very risky concept due to the fact that when not used in moderation it can destroy ecosystems. It can affect many organisms that may not be visible at the beginning. There must be a balance between positive and negative effects and this is a very thin line that is still being discovered. However, when used in proper balance this new idea could revolutionize the idea on conservation. Already ideas of nature walks on the beaches to keep the mongoose back when visitor numbers are down are being discussed. We do not know what is next for the sea turtles and how they will fare in the future, but now with this research we have a new understanding of how our actions can help the endangered species recover.
Peter Dickson
References
Leighton, Patrick A., Julia A. Horrocks, and Donald L. Kramer. "Conservation and the Scarecrow Effect: Can Human Activity Benefit Threatened Species by Displacing Predators?" Biological Conservation 143.9 (2010): 2156-163. Print.
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