A couple of our group (Annette & Nikki)are back from the Chatham Islands, where they were helping with the Black Robin post-breeding census. The following post is from Annette.
Departure was delayed several days while waiting for Cyclone Pam to pass over the islands and the sea to calm down. On arrival they found that there was little damage on Mangere Island, which had been largely protected from the full force of the wind and the seas by Pitt Island, but Rangatira had suffered significantly. Many huge old Chatham Island Ake Ake (Olearia traversii) had been blown over, and in some places this had set off a domino reaction, cutting a swathe of destruction through the bush.
The destruction around the coast was equally dramatic, with immense carpets of muehlenbeckia rolled up on the rock platforms or torn away completely, and huge straps of bull kelp wound around trees tens of metres above the normal sea level.
The Robins had obviously been affected also as they were more warier and secretive than usual, and even reluctant to come down and eat mealworms. 259 adults were present at the start of the breeding season but only 222 of these were seen during this trip. Juvenile numbers were even further down, with 49 seen compared with the 75-80 seen the last two years at this time. However the extent of the losses will not be known until the start of the next breeding season, as the birds may still have been ‘spooked’ and reluctant to show themselves; and on the other hand the combined stress of a summer drought followed by the cyclone may cause higher than usual mortality over winter.
|Male Chatham Is Black Robin|
Surprisingly, the smaller forest birds were plentiful. There were many Silvereyes, and more Fantails than I have ever seen, with groups of five to seven frequently present. Warblers flitted around busily and Tomtits were always ready to profit from the robins’ reluctance to eat the mealworms.
|Chatham Is Warbler|
|Male Chatham Is Tomtit|
|Female Chatham Is Tomtit with mealworm|
One positive effect of the storm was that most of the canopy was defoliated and so it was much lighter in the bush. This made it much easier to read the colour bands, and also it seemed warmer as the sun was able to reach the forest floor.
The contorted shapes of the trees show that the island has weathered such storms in the past and doubtless will face more in the future.