Stress is an unavoidable factor in a release program, but acute stress is critical for surviving in the wild. So in a process that involves diet changes, transmitter attachments, health checks, transportation, acclimatisation and finally release, how do we monitor and minimise the amount of stress, preventing it becoming chronic and detrimental to the animal’s health?
Years of study at the CPCP centre have identified a number of stressed behaviours including: rapidly climbing on the enclosure wire and along the wire ceiling, running very quickly on the ground or branches, repeatedly putting their head through the wire mesh while clawing at the mesh, and scratching at the door of the enclosure as if to get out. Although these animals may still be seen to eat and drink, they still lose weight.
In order to minimise these behaviours several things are done. A period of recuperation is provided after any activity, before the next one is implemented. This is supported by video monitoring at the CPCP centre, and direct monitoring at Cat Tien National Park. As direct monitoring itself can affect the behaviour of the animal this is supported by placing a camera trap at the den entrance to record time and length of activity. A program of environmental enrichment and a high quality diet is followed at both the CPCP centre and in Cat Tien and regular weighing of the animal is used as an indicator of health.
To put this into context, we were confronted with the situation where our latest release candidate, P34, was consistently sleeping in the tunnel to the underground bedbox. This makes it impossible to reach her to a) weigh her and b) release her. Within the enclosure there is already one bedbox from which we can access her and we moved a second one in there for her to get used to in the hope that she would begin to sleep in one of these, putting food near the entrance to try and encourage use.
However, when she continued to sleep in the tunnel we were left with no choice but to block the entrance. So while active one night, we used one bedbox to block the tunnel entrance.
Since then we have been watching her every night. Although we have observed her climbing on the fencing and trying to get back into the tunnel, we have seen a great reduction in these behaviours over the following nights, last night she didn’t try to get into the tunnel at all and only climbed the fence for 10 minutes.
However, her active periods have become longer, whereas previously she would spend around 30 minutes sniffing before exiting the tunnel; she now exits the bedbox immediately but is active in the enclosure for a lot longer. Reassuringly this increase in activity is supported by her eating more, both on immediate exit from the bedbox and just before re entering.
This evening, we plan to leave her in peace and set up a camera trap to monitor her feeding and activity period, we will then monitor her directly the following night. In a few days we plan to weigh her to assess her health before release. Armed with this information and the records collected at the CPCP centre we will be able to decided whether or not we need to delay the release so she has more time to recover.
This situation neatly highlights how there can appear to be a conflict between animal welfare and conservation: occasionally to achieve a conservation goal it may seem that the animal’s welfare is compromised. What I hope to instead have highlighted is the importance of information flow; without all the captive studies previously done, it would be incredibly difficult to make the informed decisions required to achieve the conservation goals of this project.