Where have all the rats in Miramar gone?

We know they’re out there somewhere but the rat population of Miramar is proving particularly elusive, or perhaps just plain camera shy.

That’s what we found recently when we set up Operation Ratcam to identify where rats in Miramar gather and feed.

Predator Free Wellington’s partner Greater Wellington Regional Council recently led this piece of citizen science. The first part of this was to place a grid of ‘chew cards’ across the peninsula to gauge the scale and location of the local rat population and its threat to native birdlife. Chew cards are an innovative product used to detect the presence of a range of small mammals including rats, mice, stoats, cats, possums and hedgehogs. Unique bite or tooth mark impressions left behind on the chew card accurately indicate just what animal you are dealing with.

Chew cards were placed along the roads, raising the question of what was happening in peoples’ backyards. In particular, there was the question of the role that compost heaps and dumpsters play in supporting rats.

Then we moved to stage two of our inventory of predators, which involved installing “backyard” cameras to identify where they gather and feed; information we will use to better target the pests through backyard trapping. The ‘ratcam’ operation involved Greater Wellington Regional Council sending out ten camera traps with citizen scientists to investigate. With the assistance of Predator Free Miramar we were able to identify willing participants and would like to thank everyone who volunteered to have a camera on their section.

The cameras were placed in a number of locations including commercial premises, outside restaurants and residential backyards and then orientated to capture images close to compost bins, rubbish bins and dumpsters.

The most striking result was how few rats and mice were seen over the three weeks the cameras were out from 15 June to 6 July 2017.

Chicken coop rat

Rats were recorded at two sites: the backyard trap and the chicken coop.

Mice at three sites: the backyard trap; behind one of the closed compost bins; and at one of the restaurant dumpster bins.

Restaurant dumpster mouse

The cameras also snapped a procession of nosey cats, both day...

and night!

And this dog was a regular evening visitor to the one restaurant dumpster, but only stopped for a quick sniff.

Although we didn’t capture a lot of rodent images with this trial we do know they are out there — albeit a little camera shy.

We have good reports of traps located close to compost heaps and other food sources delivering results so we encourage community trappers to keep up the great work! There’s also some good evidence that current rubbish disposal bins/dumpsters are working well to exclude rodents at commercial sites which is fantastic.

This monitoring trial has been helpful in continuing to build our detailed understanding of rodent behaviour in the urban landscape. Thank you again to everyone who participated in this team initiative.

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Predator Free Wellington

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Predator Free Wellington was launched in September 2016 and aims to make Wellington, New Zealand, the first predator free capital city in the world.

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