(all photographs in this blog taken at Ashley Estuary)
An oft overlooked and abused treasure
One of the joys of returning home after years away is that you see your old stomping ground through fresh eyes. Absence sharpens your appreciation for familiar surroundings. Upon return you see them for what they really are; treasures that have added to the quality of your life in more ways than you had realised. Nearly a decade after leaving Canterbury I have returned, post earthquakes, and see Christchurch city and the surrounding province through more appreciative eyes. The city has changed, irrevocably. But the wild places remain. I’ve been back just over a year and have spent almost every weekend exploring wild places, either to renew an old acquaintance or, I’m ashamed to say, to discover some of these treasures for the first time; places I had overlooked when I lived here last.
One of the special places I had not discovered that first time around was the Ashley River / Rakahuri estuary. Now it is my most regular bird watching spot as I record the seasonal comings and goings of the birds that live or visit there. There is a boyish joy in spending hours getting filthy from lying prone in mudflats, or belly crawling through coastal reeds to get close to, but not disturbing, flocks of feeding godwits, nesting dotterels or courting terns. In conservation circles, Ashley-Rakahuri has long been recognised as a significant natural wildlife resource. The river and estuary are included in a list of wetland sites that meet the criteria for classification as being of international importance by the International Union for the Conservation of Nature (IUCN). Below the State Highway One bridge, the Ashley-Rakahuri River is tidal, and in combination with the mouth of Saltwater Creek, forms a largely unmodified estuary containing more than 150 ha of mudflats and shallow water, which is excellent feeding habitat for shore birds. It is a common stopover site for migrating birds whether they are those that migrate within New Zealand or to and from often very distant overseas locations. The estuary is also a handy feeding area for birds that nest in the riverbed.
Sadly, while these outstanding ecological values are recognised in conservation-friendly circles, they are not appreciated by everyone. In addition to the usual introduced weeds and predators, one of the biggest threats to the native plants and animals that make the estuary home is human beings; in particular their indiscriminate use of all-terrain vehicles in the fragile tidal environment. These vehicles compact or breakup delicate sedimentary structures, crush crustaceans and other animals living in the mud, facilitate the introduction of weeds, disturb nesting birds to the point they can abandon their nests, and physically run over nesting birds and their eggs. In spite of large signs prohibiting vehicles from the tidal zones at all times, and the braided river channels during nesting season, every time I visit Ashley the exposed mudflats and sand banks are marked afresh by the tyre tracks of these vehicles.
But people are also helping to protect the river and estuary and the birds that live there. Chief among them are the members of the Ashley-Rakahuri Rivercare Group. A community group formed in 1999 to assist with management of the lower reaches of the Ashley River, the group’s main aims are to protect birds and their habitat in the riverbed and estuary, to monitor breeding success, and to promote these activities to the wider public. Rivercare folk work closely with the Department of Conservation, Environment Canterbury and the Waimakariri District Council to protect and enhance river and estuarine environments. Awareness campaigns, regular trapping and bird monitoring began in earnest in 2004. Since that time, annual surveys of numbers and breeding success indicate that bird populations on the managed portion of the river are at least holding their own (you can learn more about and donate to the Ashley Rivercare group here.) One of my favourite birds at Ashley is regarded as the area’s iconic species, the ngutupare or wrybill (Anarhynchus frontalis). It is the only bird in the world with a side-ways turning bill and is endemic to New Zealand. A small plover, the ngutupare only breeds on the braided riverbeds of Canterbury (apart from just a few pairs in inland Otago). The Ashley-Rakahuri is one of its northern-most breeding sites. The Rivercare Group’s website reports that numbers of this rare and important species have been relatively stable on the river during the last few decades, with 5-8 pairs normally nesting annually. But many more wrybill than that visit the estuary on the way to and from their nesting sites. I have seen flocks comprising 50 to 100 birds busily gleaning the mudflats, filtering bill-fulls of mud to sieve out the minute crustaceans they feed on.
Two other important and threatened species native species that breed on the Ashley-Rakahuri River are the tarapiroe (black-fronted tern – Sterna albostriata) and the black-billed gull (Larus bulleri). Over the last 20-30 years, numbers have declined substantially (particularly of gulls), mainly due to weed invasions, predation by introduced animals and human disturbance. Again, while humans can be the saviour of these threatened birds – the black-billed gull is one of the rarest gulls in the world – they can also be their biggest threat. In December 2012 more than 50 black-billed gull chicks were stoned to death by human attackers despite signs asking people not to disturb the endangered birds while they are nesting.
While the protection efforts at the Ashley focus on the wrybill, black-billed gull and black-fronted tern, many other bird species benefit. The river and estuary are home to such other key native species as the tuturiwhatu (banded dotterel – Charadrius bicinctus), the poaka (pied stilt – Himantopus himantopus) and the torea (pied oystercatcher – Haematopus ostralegus). A very very rare kaki (black stilt – Himantopus novaezelandiae) has bred occasionally on the river in recent years (mated with a pied stilt).
Other native birds I regularly see include pied, little, spotted and black shags; royal spoonbill; white and white-faced heron; grey teal and New Zealand
shoveler, paradise, and scaup ducks; Australian coot; harrier; pied and variable oystercatcher; kingfisher; white fronted and Caspian terns; red-billed and black-backed gulls; grey warbler, silvereye, fantail. Migratory visitors I have seen include eastern bar-tailed godwit, whimbrel and knots. The estuary is also home to large number of introduced game birds such as black swan, mallard and Canada geese; and introduced field birds such as skylark, chaffinch, yellowhammer, redpoll, sparrow and goldfinch. This list is by no means exhaustive; many other species are recorded as residents, regular or occasional visitors.
The Ashley is a treasure. But it is a treasure under threat. The Rivercare group and other conservations are doing their bit, but we all have a role. Just as drinking and driving has become a social no-no, we should be similarly outraged when ignorant (or uncaring) idiots drive their vehicles onto the estuary or through the braided river channels; when folk let their dogs run free among the sand and shingle banks and mudflats at nesting times.
The Kiwi culture of not wanting to say anything, of “minding our own business”, of tolerance rather than action, does our special places and animals no good at all. Reporting offenders, educating yourself and your friends, joining active groups like Rivercare or Forest and Bird . . . these are the ways you can make a difference, and help ensure the beautiful, unique and precious places like the Ashley and its wildlife not just survive, but thrive.