Iguanas Face Severe Health Challenges — Because Tourists Are Feeding Them Too Much
Driven by compassion or pure fun, tourists across the world do not give a moment's thought before they feed wildlife. Already imperiled iguanas may likely become the next victim of their fad, suffering further physiological problems, according to a recent study published in Conservation Physiology.
The study, conducted by Dr. Charles Knapp of the John G. Shedd Aquarium in Chicago and colleagues, compared two groups of iguanas over two research trips made in 2010 and 2012. They collected blood and faecal samples of both male and female northern Bahamian rock iguanas exposed to tourists and the iguanas inhabiting non-tourist visited island, and compared them for differences in physiological value and endoparasitic infection rates.
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Listed on the IUCN Red List of Threatened Species, the Bahamian rock iguana is among the most endangered lizards in the world. "Although large-scale hunting and egg-collecting activities threaten wild iguana populations, the biggest threat to the wild existence of these lizards is habitat loss," according to Green Iguana Society.
The study did not find a difference in the body condition of the two groups of iguanas. However, dietary nutrition differed in the two groups. The iguanas (both male and female) from islands exposed to tourists suffered from a 100 percent endoparasitic infection rate and showed notably different levels of glucose, potassium, and uric acid. Male iguanas from the tourist areas showed different levels of triglycide concentrations, selenium, packed cell volume, copper, magnesium, copper, cholesterol, cobalt, and calcium. The female iguanas from the same group differ significantly in ionized calcium.
While both sexes on visited islands eat food distributed by tourists, male iguanas aggressively consume provisioned food which explains the huge physiological differences in males between populations, according to Knapp. Tourist-fed iguanas show higher concentration of glucose, excessive diarrhea, and less potassium because they are fed too many sugary foods such as grapes.
The raised cholesterol level in tourist-fed male iguana indicates an introduction of meat in their diet, while the higher uric acid level in both male and female iguanas specifically suggests that animal protein (likely ground beef) has been added to their diet. The altered biochemical concentrations in the iguanas could impact long term health and population stability, according to Knapp. The increased population density of the endangered species as a result of tourist feeding is beneficial only to an extent, but may lead to unnaturally high densities and also prove problematic, if supplement food is discontinued for some reason, said Knapp.
The changed feeding pattern may also adversely impact plant community dynamics. The iguanas on these islands spend more time foraging in the beachy, touristy areas, rather than further inland, which disrupts the marine and plant life balance.
Knapp recommends several measures to mitigate the impact of unhealthy food. Banning feeding altogether is unlikely to work, he says. Instead, tour operators could sell food pellets packed with more nutritionally balanced diet, to help mitigate improper iguana diets. A broad education campaign, avoiding referencing feeding iguanas on advertisements, and serious discussions among wildlife stakeholders are some of the other recommended steps.
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