Wild in the city IV – the Ashley-Rakahuri

The criteria for my Wild in the City series is that the focus of each episode in the series be a wild place within or close to Christchurch City and readily accessible. The Ashley-Rakahuri River meets these criteria and more.

The Ashley-Rakahuri River - a braided gem

A braided gem – Photo courtesy of Ashley-Rakahuri Rivercare Group

A little treasure – the Ashley-Rakahuri

There are far mightier braided rivers in Canterbury, but the modestly sized Ashley-Rakahuri is an ecological gem, a taonga* of a value disproportionate to its size.

For the most part the Ashley-Rakahuri weaves through highly modified rural farmland where indigenous natural New Zealand has almost been scrubbed from existence. But the braided river channels of the river itself are a largely unmodified natural environment that has been a unique feature of the Canterbury plains for eons.

Braided rivers are rare in the rest of the world, with New Zealand considered a hot spot, and Canterbury the centre of that, with 59% of the country’s braided river surface area. They are the home of highly adapted braided river specialists, chief among them being the birds.

bath time - tarapiroe - black-fronted tern - braided river specialists

bath time – tarapiroe – black-fronted tern – braided river specialists

The Ashley-Rakahuri is a smaller braided river and is rain fed, originating in the Canterbury foothills, rather than glacier-fed and originating from the eastern slopes of the Southern Alps as the dominant braided rivers of Canterbury such as the Waimakariri, Rakaia and Rangitata do. But what the Ashley-Rakahuri lacks in size it more than makes up for in variety. Among its labyrinthine waterways, dynamic shingle islands and stony banks breed some of the most rare and endangered birds in the world. In a relatively short span of riverbed quite close to the township of Rangiora nest three of the principle and most threatened braided river specialists: The black-billed gull (the most endangered gull in the world), the unique wrybill (under threat and the only bird in the world with a bill that bends sideways), and the beautiful black-fronted tern (also an endangered species).

The world's most endangered gull - the black-billed gull - nesting on the Ashley-Rakahuri

The world’s most endangered gull – the black-billed gull – nesting on the Ashley-Rakahuri

Ngutuparore - the wrybill - the iconic braided river bird

Ngutuparore – the wrybill – the iconic braided river bird

Tarapiroe - the black-fronted tern - in flight above the Ashley-Rakahuri waters

Tarapiroe – the black-fronted tern – in flight above the Ashley-Rakahuri waters

Where the Ashley-Rakahuri reaches the sea, just 25km north of Christchurch, it spreads out into a large, generally unmodified estuary that is ranked as an internationally important wetland with a host of resident and seasonally visiting birds. It is a vital stopover site for birds migrating up and down the coast, and beyond; including the iconic kuaka (bar-tailed godwit) and other Arctic migrants that live out their winter in our summer.

Karoro - black-backed gull chick with a penthouse view - Ashley-Rakahuri Estuary

Karoro – black-backed gull chick with a penthouse view – Ashley-Rakahuri Estuary

Unfortunately, the ecological values of these braided river systems are increasingly threatened; most have been invaded by introduced weeds and introduced mammalian predators, and are further degraded by a wide variety of human activities. From its gorge, a popular swimming picnicking and fishing spot, to its mouth, the Ashley-Rakahuri, being so accessible and so close to Christchurch, is particularly vulnerable to these pressures. The numbers of birds along the river have declined and its ecological rating downgraded accordingly, from ‘outstanding’ to ‘nationally important.’

Safe among the stones? Like the other river breeding specialists, the banded dotterel is a threatened species under risk from human-caused environmental degradation

Safe among the stones? Like the other river breeding specialists, the banded dotterel is a threatened species at risk from human-caused environmental degradation

male banded dotterel with its chick  among the river stones

male banded dotterel with its chick among the river stones

young warou - welcome swallow - beg to be fed

young warou – welcome swallow – beg to be fed

But, being so small in comparison to the bigger braided rivers, The Ashley-Rakahuri also offers a unique opportunity for effective intervention; initiatives to protect the river in places where the most threatened of birds are known to feed and breed – predator trapping, weed clearance, public education, vehicle discouragement and monitoring – are showing signs of at least stopping the decline of the endangered species, perhaps even reversing it.

Trapping of introduced mammalian predators helps protect these vulnerable tarapiroe chicks hidden among the stones

Trapping of introduced mammalian predators helps protect these vulnerable tarapiroe chicks hidden among the stones

While the protection efforts at the Ashley-Rakahuri focus on the wrybill, black-billed gull and black-fronted tern, many other bird species benefit. The braided river is 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). The very rare kaki (black stilt – Himantopus novaezelandiae) has bred occasionally on the river in recent years (mated with a pied stilt) and over-wintering kaki are regularly seen in small numbers on the estuary.

tern fish exchange

courting tara – white-fronted tern – share space on the Ashley-Rakahuri with their more rare black-fronted cousins

juvenile kaki - black stilt - benefit from the protection efforts on the Ashley-Rakahuri

juvenile kaki – black stilt – benefit from the protection efforts on the Ashley-Rakahuri

white-faced heron are found throughout the river, but gather in big numbers at the estuary

white-faced heron are found throughout the river, but gather in big numbers at the estuary

Migratory wading birds are the spring through to autumn stars of the estuarine environment. Here I have seen godwit, knots, whimbrel and turnstone.

A  turnstone, turning stones!

A turnstone, turning stones!

The whimbrel usually hangs out with godwit on the Ashley Estuary

The whimbrel usually hangs out with godwit on the Ashley Estuary

godwit and knots share space on the Ashley-Rakahuri Estuary

godwit and knots share space on the Ashley-Rakahuri Estuary

The number of resident species at the estuary is also substantial. Along with the mudflats, dunes, sand and shingle banks are freshwater ponds and creeks, reed and raupo beds, scrublands and grassy flats, providing a multitude of environments for birds to live, breed and feed in.

karuhiruhi - pied shag - nest above ponds on the edge of the estuary and hunt in the estuary itself

karuhiruhi – pied shag – nest above ponds on the edge of the estuary and hunt in the estuary itself

Caught in an estuarine sandstorm - Toreapango - variable oystercatcher

Caught in an estuarine sandstorm – Toreapango – variable oystercatcher

An adult red-billed gull scolds a juvenile. Confusingly, juvenile red-billed gulls have black bills

An adult red-billed gull scolds a juvenile. Confusingly, juvenile red-billed gulls have black bills

The native birds I have seen along the Ashley-Rakahuri include: the shags (pied, little, spotted and black); the large waders (Australasian bittern, royal spoonbill, white heron and white-faced heron); the intermediate-sized waders (spur-winged plover, South Island pied oystercatcher and variable oystercatcher and oystercatcher hybrids); the waterfowl (black swan, grey teal, New Zealand shoveler, paradise shelduck, New Zealand scaup and Australian coot); the terns (black-fronted, white-fronted and Caspian); the gulls (red-billed, black-billed and southern black-backed); and the birds of the forest, air and riverbank (harrier, welcome swallow, kingfisher, grey warbler, silvereye, and fantail).

white heron spearing

The kotuku is a regular winter visitor to the Ashley-Rakahuri estuary

Another large white wader that inhabits the estuary - the amazing royal spoonbill

Another large white wader that inhabits the estuary – the amazing royal spoonbill

A kurwuwhengi (NZ shoveler drake) with a kuaka (godwit) in the background - Ashley Estuary

A kurwuwhengi (NZ shoveler drake) with a kuaka (godwit) in the background – Ashley Estuary

Parekareka - spotted shag - can be seen at the Askley-Rakahuri estuary all-year round

The beautiful Parekareka – spotted shag – can be seen at the Askley-Rakahuri estuary all-year round

The estuary is also home to large number of introduced game birds such as mallard and Canada geese; and introduced field birds such as skylark, chaffinch, yellowhammer, redpoll, sparrow and goldfinch.

The glorious song of the introduced skylark is heard in spring throughout the Ashley-Rakahuri river

The glorious song of the introduced skylark is heard in spring throughout the Ashley-Rakahuri river

The above lists are by no means exhaustive as they are only my observations; other species are recorded as regular, occasional or rare visitors.

* treasure

A torea - South Island Pied Oystercatcher. The Ashley is known for being a place where SIPO and Variable Oystercatcheres hybridise.

A torea – South Island Pied Oystercatcher. The Ashley is known for being a place where SIPO and Variable Oystercatcheres hybridise.

Kotare -  the sacred kingfisher - favours the estuary but can also be seen upriver perched above the deeper pools

Kotare – the sacred kingfisher – favours the estuary but can also be seen upriver perched above the deeper pools

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Kawaupaka – little shags – also nest on the edges of the estuary and hunt its waters – they are regularly seen upstream as well hunting within the deeper pools

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5 thoughts on “Wild in the city IV – the Ashley-Rakahuri

  1. amazing photography.not only the clarity, but capturing the moment with a fish or insect or landing or sandstorm – you must have been there for hours! am ashamed as a Christchurch person to say I didn’t even know about some of those birds. The spotted shag’s fabulous colours . Hurry up with the book!

    Bruce

  2. Pingback: A little treasure – the Ashley-Rakahuri « Conservation blog

  3. I came to your blog via DOC’s Conservation blog. Fantastic photos and story Steve. You really capture the diverse and gorgeous occupants of our wonderful braided rivers. I love them all dearly. They are our little friends who deserve our care and attention. I can’t bear that they get harmed by people’s inattention to their needs and careless actions. Let’s do all we can to live side by side with them. We can keep our dogs and vehicles out of their habitat, and move away from them when they try to draw us away from their nests in springtime. We can kill wild cats, stoats, ferrets, rats, hedgehogs so their babies don’t get eaten. We can remove the introduced shrubbery and trees that makes their habitat useless to them. Let’s do it.

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