Raising for Release: a Guide to Growing Wild

By Lisa Horn

In our daily lives, jumping into things without proper preparation might leave us kicking ourselves for not planning ahead. You can have all the equipment you need for a successful camping trip, but if you’ve never set up a tent or started a campfire before, you might not have the most pleasant of experiences.

In conservation-breeding programs, however, preparing for everything that lies ahead is of the utmost importance. Many captive-bred animals, raised in an artificial environment, lack the required ‘street smarts’ to survive in the wild. For these animals, being unprepared for their release is literally a matter of life and death.

The Keauhou Endangered Bird Conservation Center is part of the Hawaii Endangered Bird Conservation Program

Conservation-breeding facilities have a daunting task. They need to find the right balance of raising animals that are content and healthy (but not too pampered), and also well-equipped with their natural skillsets and behaviours.

On the surface, Hawaii may appear to be a paradise teeming with biodiversity and avian life, but the state has the unfortunate title of being the bird extinction capital of the world. In fact, three-quarters of Hawaii’s surviving endemic bird species are listed on the Endangered Species Act, with some populations having dwindled to only a handful of individuals. The Hawaii Endangered Bird Conservation Program (HEBCP) works with some of Hawaii’s most endangered bird species. A recent article from Frontiers of Veterinary Science discusses how the HEBCP faces the high-stakes challenge of raising endangered species for release.

Click on the tiles below to read about the ‘Opportunities to Thrive’:


Our shrike parents are given natural materials to make their own nest. The female incubates the eggs and they raise their own young.

Being in a captive environment can be an incredibly stressful experience for wild animals. You may have been to a zoo and noticed an animal like a tiger pacing incessantly around its cage. This type of repetitive behaviour which lacks an obvious function (called sterotypies) can be seen in captive animals and is often a red-flag for poor welfare. Since stereotypies are thought to come, at least partially, from an animal’s inability to act as it would in the wild, providing choices and more things to do are a way to restore healthy, natural behaviours, which animals will need after release.

The HEBCP team keeps birds busy with activities they would normally do in the wild, like starting a family. They promote a natural experience by allowing birds to construct their own nests and offering a choice of nesting materials and nesting locations. The single-minded focus on building nests, incubating eggs, and raising chicks prevents problem behaviours and also encourages positive, natural behaviours, like pair bonding.


Our Oregon spotted frogs in BC are provided with natural environments – complete with algae and scum!

At the enclosure level, opportunities to act in a natural way are built in. Just as we might escape to our bedroom when we need some time alone, animals need to be able to get away from uncomfortable situations like bad weather or unwanted social interaction. Consciously building in opportunities to take shelter, bathe, exercise, and forage gives animalschoice and control over their activities and surroundings, reducing stress and problem behaviours, and also helps maintain wild, species-typical behaviours.


The yellow-banded bumble bees in our breeding program are kept under red light because they can’t see that colour and it won’t disturb them.

In addition to preventing negative behaviours that come from a captive environment, a critical goal in conservation-breeding programs is keeping animals as wild as possible. To this end, the HEBCP uses remote-monitoring techniques, like one-way glass and CC-TV, to minimize human interaction. The team can check in on birds without disrupting them. They also use these techniques to search proactively for signs of well-being and make improvements along the way, instead of simply waiting for signs of poor health to become apparent, where more hand-on interventions may be required.


Our headstarted turtles spend the winter together in simulated natural ponds. It can be close quarters but they seem quite comfortable!

When deciding who gets to live with whom, a careful consideration of a species’ social behaviour is required. The Hawaiian crow (Corvus hawaiiensis) is the world’s most endangered crow species. The last two wild birds vanished in 2002, but the HEBCP has been working hard to help this clever and charismatic bird make a comeback in the wild. Young Hawaiian crows are very sociable and like to play. One youngster was even seen picking flowers and adorning the feathers of a companion. Adults, on the other hand, are fiercely territorial. This means juvenile birds can be housed with other juveniles, but when they reach maturity, they move to more private settings: a breeding aviary for them and their sweetie, away from the prying eyes of their neighbours. Housing breeding pairs in a socially-appropriate way, well-separated from other crows, also seems to be increasing their reproductive success.


Our Taylor’s checkerspot caterpillars are fed the exact same plants as they would eat in the wild so they are able to locate and digest them when released.

Being able to find and handle wild foods is crucial for survival after release. The endangered palila (Loxioides bailleui)is a species of Hawaiian honeycreeper with a heavy finch-like beak, perfect for breaking through the tough, fibrous pods of the mamane tree (Sophora chrysophylla). The palila relies almost entirely on resources from this tree; even its chicks are fed larvae from mamane pods. The mamane tree, just like the palila, is found nowhere else on earth.

Sometimes, captive-reared birds are not proficient at processing the pods to get to the highly nutritious seeds. Without having mastered this essential foraging skill, birds could quickly perish in the wild due to starvation. This is why the team at the HEBCP tests the palila’s competency. Birds are given a set number of pods and their skill level is tracked by seeing how many pods have been successfully opened and how many are left.

The take-home message:

Back in Canada, Wildlife Preservation Canada is also working hard to master this balancing act and prepare their animals for success in the wild. By providing natural environments and diets, privacy, and appropriate group sizes, we see the animals in our care thrive and display a full array of normal behaviours.  Our efforts to provide the right conditions are rewarded with good breeding and high survival.  Shrikes released from our conservation breeding program return from migration at a rate at least as high as wild birds.  A wild population of Oregon spotted frogs has been re-established at a historic site with froglets from our breeding and headstarting program.

Planning pays for conservation breeding programs, because when you’re working with critically endangered species, you might not get more than one shot at making it work.

Greggor AL, Vicino GA, Swaisgood RR, Fidgett A, Brenner D, Kinney ME, Farabaugh S, Masuda B and Lamberski N. 2018. Animal Welfare in Conservation Breeding: Applications and Challenges. Frontiers in Veterinary Science. Volume 5, Issue 323, 18 December 2018.

Get access to the published paper 

Lisa Horn

Lisa Horn

Guest Blogger – MSc Candidate at York University in the Stutchbury Lab

Lisa is an ecologist with a passion for wildlife and conservation. Lisa has wide-ranging experience in conducting ecological inventories, assessing environmental impact of proposed developments, and navigating the framework of environmental legislation. She has a special interest in ornithology and species at risk and is currently investigating the effects of climate change in wintering habitats of migratory songbirds on their arrival condition in Ontario.