Blog Archives

Wild ID

7/20/2012

Giraffes fascinate adults and children the world over. But this gentle and iconic animal is not only special in itself, it also indicates the health of African savanna ecosystems, home to the greatest diversity of large mammals and the most spectacular displays of wildlife in the world. Humans evolved in the African savanna and these landscapes hold a special place in our hearts. But savanna ecosystems are in serious trouble - agriculture, deforestation, illegal hunting, and disease are decimating wildlife populations. Giraffe numbers have declined by one-third in the last decade alone.

Maasai Giraffe in Tarangire National Park, Tanzania.

Classic African savanna in Tarangire National Park, with Acacia trees in full bloom.

Through the Environmental Studies Program at Dartmouth College, we are studying giraffe in the Tarangire-Manyara Ecosystem using a special tool: state-of-the-art computer-assisted photographic identification to follow individuals throughout their lifetimes, without ever laying a hand on them. Traditional capturing and marking of animals for identification purposes is traumatic and expensive, but our methods are a fraction of the cost and have no negative effect on the animals.

So how does it work? Every giraffe's fur pattern is unique to that individual. We use a computer program called WildID, developed by software engineers at Dartmouth College, which can rapidly sort through thousands of our photographs to tell us which of the patterns we have previously seen. By "capturing" the animals on film during one survey, "marking" them in our computer database as an individual with a unique pattern, and "recapturing" them on film the next time we survey - and by recording the GPS location of each giraffe when we take its photograph - we can track hundreds of individuals to see where they move, whether a female has a calf, and how long the calves and adults live.

Below is a sample of photographs that we input into the WildID program. The program uses algorithms to match patterns with each other, so we know whether two different photographs are the same animal. Notice the wide variety of fur patterns - and how beautiful they are!

Using information about survival, reproduction, and movements from our photographic database, we can learn how differences in vegetation, predation, disease, and human activities are affecting giraffe populations in the Tarangire-Manyara Ecosystem. Unlike the nearby Serengeti, large parts of the Tarangire-Manyara Ecosystem are not protected. Our long-term goal is to use our information to provide effective conservation measures to ensure the future of wild giraffes and all the creatures of the savanna.

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Scavengers in the Savanna's Food Web

7/6/2012

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Scavengers are animals that eat dead animals. In the Maasai Steppe Ecosystem where the Wild Nature Institute's scientists work, there are many scavengers which feed on the numerous animals that die from natural causes, or clean up the carcasses after a predator is finished. Vultures, hyenas, jackals, and even predators like lions often scavenge food.

This lioness had just killed a full-grown buffalo. Scavengers were not far behind.

What would happen on the African savanna if there were no scavengers? Dead animals would pile up and take a long time to decompose, especially in drier climates where there are fewer decomposers such as fungi. Therefore, scavengers play an important role in the savanna ecosystem.

Hyenas are the undisputed top scavengers of the African savanna, with specialized jaws that can crush bones. These spotted hyenas can drive a leopard or lion off its kill.

Black-backed jackals are often spotted at the scene of a lion kill.

Avian scavengers like White-backed Vultures and Marabou Storks have no feathers on their heads - otherwise, their heads would get covered with blood and tissue from a carcass, which would then become a source of disease.

The White-backed Vulture is listed as Endangered on the IUCN Red List.

The massive Marabou Stork may have the largest wingspan of any living bird, and can weigh up to 20 pounds!

Scavengers also provide another service. Their presence helps scientists to locate recent predator kills so we can document life - and death - in the savanna.

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