An elephant stands in a river while eating a leafy branch. Scientists are studying T3 hormone levels to determine why elephants are losing their appetite. Photo by Lesli Whitecotton.

Rapidly changing environments have serious consequences for native animal populations. Anthropogenic pressures brought on by human settlement often force large land mammals like the African elephant (Loxodonta africana) to adapt much quicker than natural evolution pace accommodates. Their daily and seasonal rhythms have been accosted on several fronts. The most severe effects stem from the loss of habitat combined with a warming world that has decreased vegetative nutritional access. Dr. Isabelle Szott led an international group of conservation biologists and endocrine researchers from South Africa and the UK to investigate how these human-caused effects may be detected using metabolic hormones, such as triiodothyronine (T3), without waiting for body condition and reproductive rates to deteriorate at the population level.  

Endocrine markers, such as thyroid hormones, provide significant conservation value for monitoring and quantifying the energetic state of the elephants and their caloric intake. Having a sufficient caloric intake directly affects the animals’ wellbeing and ability to reproduce. Thyroid hormones like T3 that control metabolism and appetite have been studied in captive populations for this reason. However, to be useful in management efforts of wild populations, the correlation of hormone concentration and the environmental factors of concern in their natural habitat must be well understood.  

To that end, the scientists collected 188 fecal samples from elephants at the Madikwe Game Reserve in South Africa. They extracted T3 from each sample and measured its concentration using Triiodothyronine (T3) ELISA Kits (K056-H) from Arbor Assays. Population, temperature, and food availability, as quantified by the normalized difference vegetation index (NDVI), were also measured. The researchers found that increasing NDVI was related to higher concentrations of T3, demonstrating that elephants increased their food consumption and energy expenditure as would be expected with more vegetation available. However, that relationship disappeared as the environment’s temperature rose, indicating that the elephants reverted to a resting metabolic state during heat waves regardless of food availability. This could have serious implications on the native population’s health as climate change continues to create warmer conditions, disrupting their natural foraging and migration patterns that accommodate the seasonal variation in vegetation growth.  

While the environmental implications are bleak, studies like this are vital in understanding the most effective strategies that wildlife conservation managers can use to keep elephant populations healthy, such as providing additional targeted water sources and forage for the animals in their region.  

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