Pigeon Spotting

Years ago, I was at an ecology conference where scientists were sharing the results of a study on our native pigeon or kererū. They’d been tracking the long-term decline of kererū in native forests; some of the birds they’d been monitoring had been killed by predators during the study; others had been poached by hunters. Their conclusion was that kererū were in trouble.

Kererū, kūkū, or kūkupa are known to scientists as *Hemiphaga novaezelandiae*, the “New Zealand half-eater”, for the way they gobble up fruit and poo out the undigested seeds.

Kererū, kūkū, or kūkupa are known to scientists as Hemiphaga novaezelandiae, the “New Zealand half-eater”, for the way they gobble up fruit and poo out the undigested seeds. Photo: CC-BY-SA, Angrysunbird/Flickr

Someone in the audience stood up: a local. How could these scientists say that kererū were in decline, he asked. Why, just the other day he’d seen a flock of twenty five!

To the local, the evidence of his own eyes counted for more than years of research by scientists. But our own observations can be misleading. We tend to remember the day we saw twenty five kererū, and forget all the days we saw none at all. Also, our memories don’t stretch back very far. A few generations ago, flocks of dozens or even hundreds of kererū were not uncommon; today they’re very rare.

It matters if kererū are less common than they used to be. Our native pigeons play a vital role in the forest’s ecology: they’re the only bird species left with a big enough mouth to swallow the fruit of native trees like karaka, tawa, and matai. These trees have evolved to have their fruit eaten by birds, and the seeds passed out the other end some distance away. Now that larger birds like moa are extinct, we rely on kererū to help native forest regenerate.

The 2015 Great Kererū Count results, reflecting the distribution of observers as much as pigeons. From: greatkererucount.nz

The 2015 Great Kererū Count results, reflecting the distribution of observers as much as pigeons. From: greatkererucount.nz

One way to find out where kererū are – and aren’t – is the Great Kererū Count, a citizen science project that enlists members of the public to look for kererū locally and note down whether they’re regularly seen there. It runs September 16th to 25th. To take part, you just need to make an observation for 5 to 30 minutes, which could be in your backyard or walking in the park. You note down how many kererū you see, or if you saw none (equally important data) and enter the results at the Great Kereru Count site. You can add what the birds were doing or eating, and how common is is to see kererū in your area. You can even download an app to help count kererū on the go, or join up with the Great Kererū Count project at NatureWatch NZ.

Enlisting thousands of volunteers means kererū numbers are no longer just one person’s opinion. Last year there were over 8,700 observations, and over 19,000 kererū counted. It’s not the absolute numbers that matter, but the trends over time. As the data accumulate over the years, ecologists will be able to build up a picture of regional trends in kererū population: where numbers are healthy, and where the birds are in trouble. Most participants are in cities, so observers from out in the country are especially valuable. Looking at the map from last year, there are very few observations between Kai Iwi and Hawera, so I’ve been asking people around Whanganui to consider volunteering for half an hour and keeping their eyes peeled for kererū.

(This post appeared in the Whanganui Chronicle, 10 September 2016)

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