A dog chases a banded dotterel bird at the Ashley River. There are concerns they are also disturbing birds at the Avon-Heathcote Estuary Ihutai. Photo: Supplied
Dogs are threatening - and in some cases killing - native and migratory birds on a Canterbury estuary.
Conservationists want dogs banned from Avon-Heathcote Estuary Ihutai, a crucial stop-off point for the bar-tailed godwit on its migration to Alaska.
It is also a popular dog walking spot in Christchurch.
The estuary is home to around 33,000 birds at this time of year, including oystercatchers, gulls and little penguins.
Estuary Trust manager Tanya Jenkins said dog owners were ignoring estuary rules and letting their pets run over the mudflats, a crucial feeding spot for birds.
She said some dogs killed birds, but disturbing them on the mudflats could also be fatal.
Jenkins said birds could only feed on the mudflats at low tide, so they only had a short window of a few hours to eat enough to last the day.
"If they are disturbed by dogs it can take them up to 45 minutes before they will settle again and continue eating. By then, often the tide is coming in again so they've missed out on dinner.
"If that happens a few days in a row they get very hungry. If that happens during their migration, like for the godwits who leave for Alaska in March and need to fly 12,000 kilometres, if they don't have enough to eat they won't make it."
Tanya Jenkins. Photo: Supplied
Estuary Trust data showed the number of bar-tailed godwits had massively declined at the estuary. Last November there were about 1200 godwits, but that was only half the number recorded in 2013.
The trust wanted dogs banned from the entire estuary.
Jenkins said the big problem with many areas was the limits on dogs were simply that they be under effective control, and that was not protecting the birds adequately.
Forest and Bird Canterbury manager Nicky Snoyink agreed estuary rules were not being enforced.
"Dog are a significant threat particularly when they are running free. The lack of enforcement of the bylaw where dogs are supposed to be leashed, that's a real problem for the ecological area and the species that live there."
The Christchurch City Council had received 26 complaints since July last year about dogs in prohibited areas at the estuary. But it said none were taken further, because there was not enough evidence to identify dogs or dog owners from photos taken from a distance.
A pawprint in the mudflats, where dogs are forbidden. Photo: Supplied
Julia Knoef, owner of Checkers Dog Walking, has exercised her dogs at the estuary a number of times. She said it was a popular spot for walkers, and dog control signs were not clear enough.
"I could understand how people don't realise that some birds nest in the area, or that dogs need to be on a lead for reasons. The city council could do a lot more around the information they have available."
The Christchurch City Council planned to update its dog control policy and bylaw this year, and put in better signs. The council said it had already put in additional signage after working with the Estuary Trust.
The dogs versus birds problem is right across the country. Department of Conservation (DOC) science advisor Laura Boren said it received on average 300 calls a year about dogs, and about 10 of those were reporting a wild bird being killed.
But she said the real number would be a lot higher because many went unreported.
A dog chasing oystercatchers and godwits at Avon Heathcote Estuary. Photo: Supplied
BirdCare Aotearoa is an Auckland based charity which takes in injured wild birds. Manager Lynn Miller said many patients coming through the bird hospital were there because of dog attacks.
She said dog bites were devastating to birds, and only 2 percent of all birds coming in from those attacks could be saved.
The godwits are breeding in Alaska and will arrive back at the Avon-Heathcote Estuary Ihutai in September, exhausted and starving after a non-stop flight. Bird groups hope they will not be greeted by dogs stretching their legs.
