FRIENDS OF HOWIE ISLAND
AUGUST 2021
RECLAIMING HOWIE
Pacific Gulls flushed from their rookery, Howie Island.
WRITTEN BY REES CAMPBELL AND COL MEYERS
HOWIE ISLAND, north-west Tasmania
Howie coastline
Howie Island is a tiny outcrop of land off the north-western tip of Tasmania, hidden between Stony Point at Montagu and Robbins Island. The island sits in Robbins Passage, a stretch of water known for extraordinary tidal movements, with deep fast-moving channels cutting through sea grass and sand flats. The area is a rich recreational fishing spot and setting-out point for mutton birding and commercial fishing off outlying islands such as Walker, Hunter and Three Hummock.
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"and that's the boring, superficial description you might read in a tourist brochure, which only tells a fraction of the tale..."
The real howie Howie is a perfect miniature world with a mountain all of 5 m high covered in a forest of melaleuca, a shoreline with sandy coves and craggy rocky ridges hiding molluscs and anemones from prying eyes; muddy sand flats dotted with mini pools filled with shrimp and baby flounder, surrounded by beds of samphire, providing camouflage for oyster catcher chicks. It has a poa-covered sand dune with a 360degree view, just right for heavy Cape Barren Geese and Pacific Gulls to land on, rest and nest, and with uplift for easy takeoff. Huge boulders, remnants from a volcanic age, offer a range of mini environments or feeding platforms for the gulls to drop their heavy trophies of molluscs on.
The water surrounding Howie is clear crystal pale blue reflecting the sandy bottom, merging into deep mysterious blue/black where the riches of oxygenated water feed underwater gardens of seaweed. The native foliage of leucopogon, salt bush, corea, pigface and swordgrass offers feeding and nesting sites for the loquacious White-fronted Chats, Olive Whistlers and Crescent Honeyeaters. An exposed volcanic outcrop nearby serves as resting and wing-drying platform for gangs of cormorants, and a vantage point for the local family of White-bellied Sea Eagles to keep an eye on their kingdom and future meals.
Nearby are several piles of old ballast rocks forming small pyramid mountains underwater, where Bigbellied Sea Horses live and breed, along with hermit crabs and sea urchins. In mid-summer, the huge, orange appropriatelynamed Spider Crabs hold a mating orgy with millions entwined on the sand. Abalone are on the move and eagle rays quietly munch their way through small molluscs, often leaving perfect indented outlines in the soft sand after the tide falls. Rocks at Howie
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Pacific Gull nest, Howie Island
Pacific Gulls AND POA TUSSOCKS
Like most islands, Howie is home to sea birds. It has a sandy knoll on the northern end originally covered with tussocks of native poa, which hosts a Pacific Gull rookery; and pairs of oyster catchers nest along its shores, as do terns, Cape Barren Geese and others. Brown Quail nest amongst the tussocks and the island also supports swans, pelicans and cormorants. Many migratory waders, with whimsical names such as turnstones, curlews, tattlers and whimbrels use the rich sandflats to fuel up for their return flight to the Siberian tundra to breed.
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The Pacific Gull is magnificent, up to 65 cm long with a wingspan of up to 150 cm and weighing over 1 kg. It is strikingly coloured with a massive red-tipped yellow beak, yellow legs, an all-white body; set off by a black back, wings and tail band. The juveniles (up to 4 years) are so different they are often thought to be a separate species, known as “mollyhawks”. They are mottled brown all over and only after the first couple of years change to the spectacular and dignified white and black of their parents.
Pacific Gull (Larus pacificus) by Dr. Margot Oorebeek
Pacific Gulls are not endangered, nor even rare, but it is common creatures which drive ecological systems. There have been too many species regarded as common, and their value underestimated until they begin to slip into rarity. Habitat loss is a primary reason for so many extinctions, and currently 1 in 5 species of birds in Australia is under habitat threat. Rookeries of Pacific Gulls rarely exceed 100 birds, but the rich fishing grounds of Robbins Passage sustain one of the larger rookeries in Australia. The Pacific Gull has a varied diet, eating fish, molluscs, crustaceans, carrion, eggs and young of other sea birds, and all manner of human rubbish. The enormous population of Spider Crabs forms a large part of the local Pacific Gull diet, but they also carry hardshelled molluscs high above selected rock platforms, then drop them to break open the shell.
LUCKILY, FEW HUMANS VISIT HOWIE AND ALL INHABITANTS ARE GENERALLY ABLE TO FEED, BREED, REAR THEIR YOUNG, AND BASICALLY LIVE THEIR LIVES IN THE MANNER THEY WISH. HOWEVER, ONE COMMON ISSUE FOR CLOSE-TOSHORE ISLANDS IS WEED INFESTATIONS, AND UNFORTUNATELY, HOWIE ISLAND IS NO EXCEPTION.
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The weed threat
Col in the mallow, Oct 2010
Bird, wind, tide and human-carried weed seeds are fertilised by guano, and have no grazers to keep them under control. Rice Grass, thistles, nettles, African Boxthorn and Sea Spurge all grow on the island, but the real threat to the birds is Tree Mallow. This attractive Mediterranean plant (Malva arborea), often grown in local gardens, thrives. It is known to be a problem for birds nesting on close-to-shore islands from as disparate areas as Scotland to West Australia. The plants have a fibrous “daisy-bush” stem, but grow rapidly over two years into a dense thicket up to 5 m tall, making the area impossible for the gulls to nest in. They flower in the second year, and beautiful purple/pink flowers produce thousands of seeds, which rapidly germinate and replace older bushes. They reproduce extremely quickly and effectively.
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Pacific Gulls, like many other sea birds, like an open vantage point for nesting. The tree mallows, which we first observed as a 10 m square area in 2007, have pushed the resident gull population off the knoll into hazardous nesting sites right on the high tide mark. In just 3 years the size of the mallow thicket increased from 10 x 10 m, to almost 40 x 60 m! In 2010, we kayaked to the island and observed gulls nesting right on the high tide seawrack line… not a good career move. We looked at each other and said “someone oughta do something about that”. So we did.
After researching minimal impact weeding on the island’s tiny and fragile ecosystem, we recruited and trained a group of unwary volunteers to withstand three primary problems: getting there, timing, and stinging nettles!
Native Scrub Nettle, Urtica incisa
tackling tree mallow Robbins Passage is a notoriously volatile stretch of water – the tide rushes in and out of the channels creating extreme turbulence, and almost impossible currents to paddle against. Also it is not by chance that the wind farm is at Cape Grim – directly to the west…. the wind is fairly constant and can whip the smooth lake-like surface into confused and choppy waves within minutes. Timing is a problem as nesting Pacific Gulls are wary, lifting from the nests in a huge raucous flock when disturbed. This ruckus alerts potential predators, with unprotected nests vulnerable to attack by opportunistic crows and rats; and to cooling or heating eggs or young. Unfortunately breeding coincides with the active growing, flowering and seeding season, so the majority of work needs to be done at a less than optimal time. And less optimal not only means less effective on weeds; but autumn and spring, when the weather is fickle at best and abysmal at worst!
Native and introduced stinging nettles are downright vicious - sounds trivial but is anything but! These creeping, unobtrusive, dark green serrated leaved plants grow well in the sandy environment with each stem and each leaf edged with an armoury of razor sharp, almost microscopic hairy thorns which penetrate skin, even through light clothing, and set up a very painful response which cannot be rubbed or washed away. The nettles continue to sting for as long as the hairs remain embedded and are irritated by rubbing, washing, even breathing it seems! Our first major attack was at Easter in 2011, when we spent several days cutting down every standing mallow! This involved one team with machetes, axes or tomahawks hacking down the up-to 5 m tall, and 150 cm diameter stem plants. Following closely were the second team, who carried or dragged plants from the rookery area down the steep, nettled slopes to a gully where they stacked the plants. The third wave was armed with secateurs; they cut smaller plants left to wilt where they lay. It was easy to pull out small plants but we tried to avoid that as disturbed ground encourages germination, and we were worried about erosion. We just hoped we had not left any plants big enough to flower over summer…
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Weary volunteers, April 2010
The whole difficult exercise was repeated several times a year for the next two years. Finally we were rewarded with significantly less mallow re-growth and native pelargonium and pigface making a slow but essential comeback. We planted 500 poa seedlings as the gulls work the tussocks hard during the breeding season, standing on them for a lookout, and leaving heavy deposits of guano -the equivalent of Christmas dinner every day. The poas have trouble withstanding the annual onslaught, but the birds leave the area in winter, and heavy rains wash the fertiliser though into the knoll, and the poa tussocks emerge fresh and green in early spring, ready for the fray. Early spring of 2012/13/14 came, and we were even more delighted, as on approach we could see adult birds utilising the top of the knoll as their selected nesting sites the first time in three years this had been possible. It was so gratifying to see the birds reclaim the territory we had fought so hard for.
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OUR RESULTS HAD EXCEEDED EXPECTATIONS. NO PLANTS HAVE FLOWERED AND SEEDED FOR SEVERAL FULL YEARS, SO WE ARE HOPEFUL OF CONTINUED REDUCTION IN SEEDLING NUMBERS WITH BI-ANNUAL WEEDING PRE AND POST BREEDING SEASON. WE HAVE BEEN WEARY, FRUSTRATED, EXHAUSTED, BUT FELT FINALLY EXHILARATED AND JUBILANT TO HAVE RECLAIMED HOWIE FOR THE BIRDS.
A pile of Tree Mallow after a working bee
...hang on a minute!
Since then until now (2021), we have discovered, disappointingly, that even though we have prevented the mallows from seeding for many years, there has been significant new germination each year. So in spite of all the effort with help from numerous volunteers, some of whom are part of Circular Head Landcare, and some early funds from CCNRM, we haven't yet won the battle (although it is gradually getting easier). So what the heck is going on? It has become apparent that the birds are somehow inadvertently bringing fresh mallow seed from the mainland. We believe it's the gulls but it could also be common starlings and or
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Cape Barren Geese, all of which roost and breed on the island. Bugger! We have to get our heads around the fact that even though we have saved the colony there needs to be biannual follow up work to maintain site viability. In spite of the above frustrations the project has been extremely worthwhile from a conservation perspective.
A huge thank you to all the volunteers and unfortunate family and friends who have been sucked in to giving us a hand, arm or leg by sweet talking from Rees and Col.
References
Brothers, N., Pemberton,E., Pryor,H., Halley,V. 2001. Tasmania’s Offshore Island: seabirds and other natural features , Tasmanian Museum and Art Gallery publishing Campbell, R. 2006. A Thousand Pleasures, A Million Treasures, self-pub Campbell,R. 2012. Brazenly Pure – the Truth and beauty of Tasmania, 40 South publishing. Edgar, G.J. 2012. Australian Marine Life (2nd Ed) The plants and animals of temperate waters Reed New Holland Lloyd,S. 2012. Yellow Throat The newsletter of BirdLife Tasmania branch of BirdLife Australia Number 66, November 2012 Watts,D. 2002. Field Guide to Tasmanian Birds new ed., Reed New Holland
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