Good things take time – like breeding Galápagos tortoises

Auckland Zoo is celebrating the hatching of four tiny Galápagos tortoises, the most hatched from a single clutch to date within the small Australasian zoo population of this ‘Endangered’ giant reptile – Chelonoidis vicina.

The four hatchlings are the offspring of ‘young’ parents, 50-year-old mum Chippie and 49-year-old dad Smiley and hatched on 26 January (weighing between 74-88 grams) in a climate-controlled incubator. As the world’s largest tortoise, all going well they’ll grow a massive 2,500 - 4000 times in body mass (males like 241kg Smiley, are double the size of females) and could live for over 180 years! 

The hatchlings’ arrival after a 110-day incubation follows Chippie and Smiley’s first successful breeding in December 2017 (a first for Auckland Zoo and New Zealand) with the premature hatching of Pinta, who due to shell abnormalities and an associated untreatable infection, had to euthanased aged four months.

The Zoo’s ectotherms specialists say that this time, all four animals are indicating they’re in great health - extremely active from day one and already eating and growing in size and weight.

“While tough to lose Pinta, confirmation of Chippie and Smiley’s fertility was incredibly heartening. Now we have this very exciting upward turn that we hope reflects the sweet spot we’ve hit after years of incrementally refining our husbandry for this species,” says Auckland Zoo’s Ectotherms team leader, Don McFarlane.

“Through the training we’ve done with our four adults so we can easily physically check and take bloods from them, we know they’re in excellent health and this year’s breeding, that also saw one of the hatchling’s weights register off the charts at a whopping 88 grams, indicates the great potential of our adult females.

“However, we are reminding ourselves that everything about these slow-maturing reptiles takes time, that these are famously challenging tortoises to rear, and that success will only truly come when these hatchlings reach adulthood in 20-40 years - it’s a long game!”  (Reaching adult size and sexual maturity is dependent on how fast they grow).

Science-based care

The 13 eggs laid last October were delicately excavated by the Zoo’s Ectotherms team with all the care of an archaeological dig, then moved into an incubation environment of 30 degrees centigrade (likely to produce females) and 60-70 percent humidity - replicating wild conditions. After hatching and absorbing their yolks, the four hatchlings were shifted to a miniature habitat that they share together. 

“Here they have all the vital environmental elements they need – a temperature gradient from 35°C via an ultra-violet basking lamp down to 22°C  at night, and everything in-between, and steady high humidity (they originate from equatorial oceanic islands after all).We’ve provided varying terrain for climbing, fresh grassy bed areas that we spray with tepid water every afternoon and which they love to tuck themselves into to feel safe at night, and an outdoor area for time in the sunshine to gain additional vitamin D3 to aid calcium uptake from their diet,” explains Don.

Described by Don as a “reptilian cow”, Galapagos tortoises require high fibre, moderate protein and low sugar for their digestive health. The hatchlings and adults alike have a diet of chopped hay, and leaves and flowers from plants like dandelion, puha, and plantain. “Like kids, they do tend to gravitate to colourful sweet foods like bright hibiscus flowers and grated carrot. The latter, surprisingly high in sugar, is a rare treat for them that we mix in with their hay to stimulate their appetite”. To aid their hydration/moisture uptake, the hatchlings are also given twice weekly hour-long “bath time” in tepid water.

A common conservation story

Auckland Zoo’s Head of Animal Care and Conservation, Richard Gibson, says Galápagos tortoise species’ tragic history of over-exploitation for food, decimation by introduced mammalian predators and habitat loss, and subsequent recovery efforts, has much in common with the plight and ongoing recovery efforts for so many New Zealand endemic species.

“Amazing efforts to protect and restore the Galápagos’ wildlife and wild places by organisations like the Galápagos Conservancy and Charles Darwin Foundation and their countless supporters - through the likes of intensive captive breeding-for-release programmes for tortoise species - are seeing these reptiles and other threatened Galápagos species, slowly recovering.   

“The opportunity for Kiwis to experience these absolutely extraordinary giant reptiles here at Auckland Zoo - for some families over generations, is incredibly special. As a wildlife conservation organisation, we put enormous resources into helping conserve both native wildlife throughout Aotearoa and exotic species all over the world, including in the Galápagos Islands. None of this would be possible without our visitors.”    

Visitor viewing of hatchlings

While the seven-week-old hatchlings remain under close care for now, in a few months’ time we hope they will be able to join their parents and our other two adults in the Galápagos tortoise house where a special raised ‘island’ home for them will offer visitors great viewing. We’ll keep you posted!

Galápagos tortoise facts:

• The Galápagos tortoise is the world’s largest tortoise; males can reach 250kg and females up to 150kg
• There are 11 different Galápagos tortoise species; down from 15 when Charles Darwin first visited in 1835. Six are Critically Endangered, and three are Endangered (including the species Chelonoidis vicina which we house at Auckland Zoo). 
• Exploited for food by pirates, whalers, and merchantmen during the 17th - 19th centuries, more than 100,000 tortoises are estimated to have been harvested. Introduced mammalian species, including rats, pigs, and dogs that prey on tortoise eggs and hatchlings, and species such as goats, cattle, donkeys, and invasive plants, damaging or destroying habitat have driven their decline.
• Highly threatened, Galápagos tortoises have been protected by the Ecuadorian government since 1970. Many restoration programmes, including captive breed-for-release programmes by the Charles Darwin Research Station and Galápagos Conservancy, are having some amazing results.
• Breeding: Sexual maturity is between 20 - 40 years (dependent on how fast an individual grows to reach adulthood), and these reptiles can keep growing even up to 40-50 years old! Females use their hind legs to dig a flask-shaped hole about half a metre deep and lay up to 16 billiard-sized eggs. They will urinate in the nest to soften the soil and increase its humidity while laying. Once laid, they fill the hole and walk away. Incubation is 110 -150 days.
• Longevity: The longest-living Galápagos tortoise is 188-year-old male Jonathan

Auckland Zoo’s Galápagos tortoises: Auckland Zoo has four adult Galápagos tortoises (Chelonoidis vicina); males Smiley and Willy (both 49 years) and females Chippie (50) and Snapper (51), all of whom hatched at Honolulu Zoo and came to Auckland Zoo in 1983, and now our four new hatchlings. Auckland Zoo’s tortoises are part of the ZAA (Zoo Aquarium Association) Australasian regional breeding programme for Galápagos tortoises, and these latest four hatchlings increase the programme’s population to 20.

Zoo support to The Galápagos : Among the many conservation projects Auckland Zoo supports locally and globally through its Conservation Fund are a number in The Galápagos Islands. Grants have facilitated Massey University’s ‘Rat control for the conservation of Pseudalsophis dorsalis dorsalis’ and ‘Conservation of the Galápagos racer (Pseudalsophis biseralis’ (bothendemic diurnal colubrid snakes); and a Friends of the Galápagos project to locate the breeding rounds of the white-vented storm petrel (Oceanites gracilis galapagoensis). In addition, a travel grant supported one of Auckland Zoo’s bird specialists travel to The Galápagos in 2017 to help the Charles Darwin Foundation team artificially incubate and hand rear ‘Critically Endangered’ Mangrove finch chicks, as part of the Mangrove Finch Restoration Project.