Forest Hinge-back Tortoise

1 Overview

The African hinge-back tortoise (Kinixys erosa) is one of the most valuable tortoise species from Africa. It lives on a continent with sharply divided wet and dry seasons, so it tolerates both hot, humid conditions and up to half a year of drought.

The genus Kinixys contains six species, all from Africa, united by one shared trait: a hinge at the rear of the carapace that can fold shut. This is unique among all tortoises. Of the hinge-backs, Bell’s hinge-back (Kinixys belliana) is the most widespread and numerous and is the representative species of the group.

Chinese Name: African Hinge-back Tortoise (Forest Hinge-back)

English Name: Forest Hinge-back Tortoise

Binomial: Kinixys erosa

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Order: Testudines

Family: Testudinidae

Genus: Kinixys

Distribution: Guinea, Liberia, Senegal, Chad, Cameroon, Congo and the Central African Republic.

2 Physical Characteristics

The defining feature of the hinge-back is its movable rear carapace, which helps it evade predators and also assists breathing and egg-laying — an alternative evolutionary adaptation.

The African hinge-back is the largest of all hinge-backs, exceeding 30 cm when mature. Its carapace base colour is brown, scattered with a few yellow markings, and its sexual traits are no different from other tortoises: males have a thicker, longer tail. It is distributed mainly across central and western Africa, including Guinea, Liberia, Senegal, Chad, Cameroon, Congo, the Central African Republic and surrounding countries, with Cameroon the main exporting nation. It lives mostly in rainforest, often around swamps, riverbanks or streams.

What sets the hinge-back apart from other tortoises, beyond its peculiar crawling posture, is the fold that drops down from between the seventh and eighth marginal scutes. There, a ligament-like soft tissue lets it pull the fold partially closed when threatened — and that closing action also helps breathing and egg-laying. Among all tortoises, only this genus does this.

Another trait unique to the African hinge-back: its swimming skill rivals that of box turtles, showing its habitat is more humid than other hinge-backs, living in Africa’s true tropical rainforest.

3 General Care

Few are kept domestically, so research on this tortoise is limited to the wild — its habits and breeding. A brief introduction follows.

Habitat and climate: it lives in an equatorial rainforest climate, warm and humid all year. Because of elevation, the average annual temperature is about 25–30°C, with only a clear wet/dry split — the long wet season of 7 months runs roughly May to November.

Breeding: wild African hinge-backs may mate any month of the year, laying 5–8 eggs depending on size. Incubate at about 30.5°C and roughly 90% humidity; hatching takes 130–160 days.

Most hinge-backs are wild-collected and easily carry internal and external parasites, so deworming must be done properly. If the tortoise adapts to its new environment, breeding and hatching it is not difficult. Note that closely related species (e.g. Home’s hinge-back) dislike strong light and need large shaded areas.

4 Captive Habitat

It is demanding of its environment. Although it tolerates extremes in the wild, in captivity it needs high temperature and humidity, so many locations are unsuitable.

Temperature: keep it within about 27–30°C (day), 24–26°C and 20–22°C bands. Wild individuals have a summer-dormancy habit, so do not let it get too hot (above 35°C); at night it can drop to 20°C, but keep at least 27°C around feeding to aid digestion.

Humidity: it needs fairly high humidity, with 60–85% as the basic requirement. Though distributed across Africa and drought-tolerant, research shows high humidity suits it better; its wide range and distinct rainy season let it adapt to a broad humidity span.

Feeding focus: provide high-fibre, high-calcium, low-phosphorus food with moderate protein to keep the shell from pyramiding and the diet balanced with normal urate excretion.

Activity: it is most active when rain begins, but in extreme heat it digs into dried-up puddles to hide and conserve moisture, waiting for the next rain.

5 Feeding

Although we think of tortoises as strict vegetarians, and some keepers add animal calcium, the African hinge-back is an out-and-out omnivore that will try many things.

Diet: despite being a tortoise, its environment and feeding differ from other African tortoises — closer to red-foot behaviour. It is a standard omnivorous tortoise with higher protein needs: vegetables, fruit, weeds, snails and beetles are all eaten. Fruit should be the staple. It also needs very high humidity, at least 80–90%, with misting morning and night; a water dish is essential. It is timid and easily stressed into refusing food, especially freshly imported individuals. Basically all hinge-backs are unsuitable for beginners and count as a difficult group.

What to feed: in the wild its diet is broad, refusing little of either plant or animal origin. In captivity offer snails or insects, even animal offal as high-protein food, and for plants choose soft, moist fruit or leafy greens. Keep the diet varied — monotonous food triggers disease and nutritional excess or deficiency. Commonly eaten plants include insects, banana, leafy greens, carrion, mushrooms, snails, tomato and various melons and gourds.