Capturing the Diversity – Cat, Scat and a Pat on the back

I joined Ray, Damian and Greggy one time on one of their walks to check and maintain these stations.  The route took us between One Boat and Traveller’s Hill, passing nearby the refuse dump.  It was fairly easy walking through a flat plain of gravelly rock coated in Mexican thorn bushes.  They knew the route, but I had helped to digitise the walks they did around the island and thought it a useful idea to log the locations of the stations.  It was a good practical exercise for the guys to learn how to use GPS and record and download waypoints.

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Greggy, Damien and Ray at a cat station

Ray was carrying a sizeable rucksack.   He was a bull of a man, not particularly tall and at first sight, his round shape might make you think he was unfit.  But every walk I did with him he was at the front, and putting the lads half his age to shame.  We found the first station; they were relatively easy to spot as they had red and white tape flapping from a piece of rebar fixed in the ground and was surrounded by a circle of beach sand.  They used beach sand as the yellow always contrasted against the reds, greys and blacks of the inland soils.  Attached to the piece of rebar would be the attracting bait, usually a small piece of fish that Ray and Stedson would fish off the rocks for the day before.  The guys took a GPS waypoint over the rebar, then checked to see if the bait had been touched.  Even if part of the bait or the whole bait were gone, this would not necessarily be evidence of a cat.  The height of the bait on the rebar was critical, too low and crabs and rats could access it, too high and the birds might swoop in and capture it.  The sand was there to detect any footprints.  Crabs were easily distinguished by the lines in the sand as they dragged their shells.  Cat footprints were different from rats in size and shape.  With all this precision on a rather rudimentary piece of kit, no cat attempting to get the bait would get away undetected.

I asked Ray how many cat footprints he had seen.  He said none in the last year.  But they wanted to continue doing this for at least another six months to make absolutely sure.  The last thing would be to miss a small pocket of breeding cats that once monitoring had stopped could reproduce unchecked and damage the restoration of seabirds on the mainland.

So they reset the bait, throwing away the old fish and tying on the new from the supply in a plastic bucket.  Ray then unbuckled the rucksack and slipped it off his back, sprinkled new sand on the circle and raked it across, having removed bits of vegetative and mineral debris first.  And on we went to the next one.  A few months later, a large party was held at the Klinka Klub beach hut to celebrate the successful eradication of the feral cats.

Capturing the Diversity -Capturing the cats

Much more problematic for the sooty terns were the predation by the introduced mammals.  One of the key drivers for the bird conservation programme on Ascension had been the massive increase in feral cats on the island.  Generations of cats had been introduced on to the island since the first sailing ships arrived, some escaped and bred, and somehow managed to survive in the inhospitable environment.  The main reason for their success was the prolific abundance of bird eggs and chicks.  At one time most of the key bird species on Ascension had all bred on the main land, but, apart from the Wideawakes, the cats in particular had pushed them back to a couple of isolated cliff locations on the south east tip of the island, or the stacks and small islands around.  Boatswainbird Island, the largest of these, was where the most flourishing colonies were and now the only safe place for the Ascension Frigate Birds to breed.

There was only one way to deal with this problem and that was to eradicate the feral cats.  At first hunters were brought in to shoot or capture the cats.  Controversially, cats were often disposed of by throwing them out to sea, where a piranha-like fish called the blackfish would hunt in packs and devour them in seconds.  While at first the cats were easy to spot; they were literally everywhere, after the cull had been underway several months,  finding out where the remaining cats were hiding out became more of a problem.  They were still predating on any birds that tried to nest on land, especially the fruitful pickings at the Wideawake Fairs.  But small populations were still to be found around the rest of the island too.  Poisoning was used for a while, attracting the cats to bait laced with sodium monofluoroacetate.

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Birds and eggs under threat from the cats

Cat eradication programmes are usually conducted on island uninhabited by humans.  Here on Ascension they had to be extremely careful not to kill domestic cats. For this reason exclusion zones were set up around the bases and settlements where no bait trapping were conducted.  Domestic cats were all registered and tagged with a microchip.  In the areas around the villages traps were often used to find the feral cats, and when a cat was caught, it could be checked for a microchip and if a positive reading given could be returned to their owners; if no tag were found the cat would be put down.

As the population of feral cats continued to decline, finding the last few pockets became more and more difficult.  If any evidence of cat activity (particularly cat scat or faeces) was found, then an intensive effort to find and eradicate the cats was focused in that neighbourhood.  When this evidence dribbled out to nothing, a set of cat tracking stations were set up to make absolutely sure that every cat had indeed gone.