The Annual Cycle of Reproductive and Stress Hormones in the Gentoo Penguins - Penguins Restraint and Stress Level

Brief description

The only work that went ahead as part of this ASAC project was to look at Penguins restraint and stress level (see the referenced paper below).

From the paper:

During most research on penguins it is necessary to temporarily immobilise the birds at some time (to weigh, mark, or attach instruments). Although many penguin species seem unconcerned about a human's presence, a single approaching person has been shown to increase the birds heart rate, suggesting that the animal is aware and may be stressed. Corticosterone is one of the hormones regulating the stress reaction in birds, and in turn regulates that stress caused by immobilisation. As captured and bag restrained Adelie penguins show a three fold increase in heart rate, we can presume that this is a very stressful immobilisation technique. Restricting the stress reaction is particularly important during the breeding season to avoid nest desertion, or loss of eggs and chicks. The subject of this paper is to present a less stressful method for restraining penguins.

38 mature, male Gentoo penguins in good physical condition were used to test bag restraint methods. Resting animals were caught on the Macquarie Island Isthmus. 59 animals were used to test the effect of hood restraint methods.

There was a significant increase in corticosterone concentrations in the blood of bag restrained penguins within 10 minutes of restraint. Between 10 and 15 minutes, further changes were not significant. After 20 minutes, however, there was a second significant increase, when compared to the levels at 15 minutes. Upon release all birds were unconscious; they then showed symptoms of hysteria, such as disorientation and shaking of the head.

Corticosterone levels in the blood of hooded penguins rose significantly after 5 minutes. After 10 minutes, the mean concentration showed a tendency to decrease, when compared to the 5 minute levels. This, however, did not differ significantly to concentrations immediately after restraint. After 20 minutes concentrations rose again, and were again significantly higher than at the same time of restraint and after 15 minutes.

Both groups showed the same levels of corticosterone upon restraint. Hood restraint led overall to a lower increase in corticosterone levels than restraint with a bag. After 5, 10, 15 and 20 minutes, statistically significant lower levels in the blood were detected in hood restrained birds. The penguin's reaction to both restraint methods was identical in two respects: There was no significant increase in corticsterone concentration between 10 and 15 minutes. Secondly, concentrations were significantly higher after 20 minutes than at 15 minutes.

Lineage

Progress Code: completed

Statement: The raw data are not available, only a scanned graph of the final data.