Trackers provide insights into penguin life

This little penguin, known at the Oamaru Blue Penguin Colony as 47211, is fitted out with a...
This little penguin, known at the Oamaru Blue Penguin Colony as 47211, is fitted out with a tracking device that can monitor its location, depth, acceleration and sea temperature. Photos: Hamish MacLean
The breeding season at the Oamaru Blue Penguin Colony could start any day. Hamish Maclean talks to colony research scientist Dr Philippa Agnew about how researchers find out what the birds are up to.

The penguins at the Oamaru Blue Penguin Colony could begin laying eggs to start the breeding season any day.

But before they do, colony research scientist Dr Philippa Agnew wants to know what the little penguins are up to.

To that end, Dr Agnew and colony staff are fitting birds with tracking devices that monitor their location, depth, acceleration and the sea temperature.

Tracking  the birds’ pre-breeding behaviour could provide an important insight into the success of an upcoming breeding season.

The data  would be an important addition to the more than two decades’ worth  already collected.

"When the birds start laying eggs is the key to their breeding success," Dr Agnew said.

"So this period of pre-egg-laying must determine when they start laying eggs and then that will determine how successful they are in the season. The more we can find out about this time, the more we will be able to predict what might happen during the breeding season.

"Maybe not in an individual level, but maybe at a population level per year."

The study follows on from Dr Agnew’s 2010-12 fieldwork — with less powerful tracking devices, over three years, she observed penguins typically heading roughly 50km northeast of the colony, leaving the colony for a couple of weeks at a time.

Oamaru Blue Penguin Colony research scientist Dr Philippa Agnew, with assistance from colony...
Oamaru Blue Penguin Colony research scientist Dr Philippa Agnew, with assistance from colony staff member Aimee Horrell, fits a tracking device to a little penguin at the colony on Thursday.
Battery life was an issue then, and the devices attached in the earlier study lost track of the birds after two or three days, so the record of their movements was far from complete.

This year, with more sophisticated tracking devices, Dr Agnew was not only getting  a more detailed view of the birds’ behaviour, but complete trips to sea were being recorded. And this year also the birds’ behaviour was "the complete opposite from what I expected," Dr Agnew said.

One bird, that had a tracker attached on May 31, ventured 60km from the colony, swimming past the mouth of the Waitaki River and foraging for nine days. But most birds were getting their fill — of slender sprat or other small schooling fish about 10cm in length that make up the little penguin’s diet — no more than 10km from home.

At the start of May at the Oamaru Penguin Symposium, Dr Agnew presented her finding’s on Oamaru’s little penguins’ breeding: with a 43% survival rate in their first year, birds hatched earlier in the breeding season and those with higher body mass when they fledged had a better chance of making it through to become breeders themselves.

"In a year like this, when they’re travelling really close and foraging near the colony — and they’re all really good body weights — you might expect that they start breeding early, because there’s obviously plenty of fish nearby," Dr Agnew said.

Last year the colony was home to 189 breeding pairs. At this time tourists who come to watch the birds coming in at night are told to expect about 50 birds, but 130 returned to the colony in one night this week. 

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