Most of the white-flippered penguin colonies in the Christchurch area are below near vertical coastal bluffs which have been prone to rock fall during the recent series of earthquakes. Fortunately for the penguins, the largest rock falls have occurred on the more exposed parts of the coastline which are least preferred habitat, and mainly at times of the year when few if any birds were ashore. As a result, the overall effect of the earthquakes on the penguin population appears to have been minimal with the 2010 and 2011 breeding seasons being largely unaffected.
The main penguin colonies in Harris Bay have been monitored over the last year and a half to see how the earthquakes have affected them. This is a relatively sheltered area of rocky coastline backed by bluffs just to the east of Christchurch City. The first and strongest earthquake (mag. 7.2 on the Richter scale) occurred on the 4th September 2010 just prior to the main laying period when at least 50% of the adult birds would have been ashore. It was centred to the west of Christchurch and caused little damage in the Harris Bay area. All of the colonies were showered to some extent with fine debris from the bluffs and slopes above, and there were a few small rock falls. Only one of the 130 nest boxes in the Bay was damaged; it received a direct hit from a large rock. All of the nest boxes were checked straight after the earthquake and cleared of debris where necessary, and the penguins proceeded to lay and incubate as if nothing had happened.
During the next six months there were 19 aftershocks in the Christchurch area of mag. >5.0 including the two that devastated the city centre. These were on 26th December 2010 when only a few chicks remained in the colonies, and on 22nd February 2011 when only the late moulters were ashore. This spate of aftershocks had much the same effect in the Harris Bay area as the September earthquake with the addition of a few more small rock falls. The Godley Head area was closed to the public during some of this period because of the risk of further earthquakes and resulting rock falls. Despite this it was possible to check all of the smaller colonies on one or more occasions during the 2010 breeding season, and the largest colony frequently on a semi regular basis. The key indicators of breeding success for the season were close to long-term averages, which suggest the penguins were relatively unfazed by the ongoing seismic activity.
There were two more large earthquakes (mag. 6.4 & 5.9) on 13 June 2011 which were centred under the eastern suburbs of Christchurch. These brought down rock falls from most of the coastal bluffs in the area including numerous localized falls in Harris Bay. In the event 23 nest boxes were buried under slabs of basalt and volcanic debris that had fallen from the bluffs. Fortunately there were no penguins ashore at the time, and their next breeding season was still three months away. Efforts were made to clear the buried nest boxes and by September all but 7 were again available for use. Between September 2011 and January 2012 there were a further 10 earthquakes in the Christchurch area of mag. >5.0. Despite these ongoing upheavals the penguins laid earlier and fledged more chicks per pair during the 2011 breeding season than the long-term average.
Nest box occupancy in Harris Bay decreased by 11% between the 2009 and 2011 breeding seasons, which was a reversal of the trend over the previous decade. While it is tempting to conclude this reduction was somehow directly related to the earthquakes it has more likely been for demographic and behavioural reasons. Chick production during the 2008 season was poor, and as a result recruitment of new breeding birds was expected to be low in 2010 and 2011 (ie. when they would be 2 and 3 years old).There was some evidence that a few pairs were nesting in inaccessible places in new rock piles during the 2011 season and not recorded. Regardless of the reasons, if the medium term positive trend in penguin numbers around Banks Peninsula continues the deficit will quickly be made up.
During November 2010 (before, during and after our earthquakes), the Trustees of the White-flippered Penguin Trust invited a camera crew from TV3 to visit the penguin colony on Motunau Island. With the blessing of DOC who accompanied us, we all witnessed the arrival and departure of thousands of birds and now have a library of wonderful photographs and TV footage. Motunau Island, off the coast of North Canterbury, is the main breeding colony for the White-flippered penguin.
On the first day, 2 trustees, Chris and myself, flew by helicopter to the island to prepare for the remainder of the crew who were to arrive the next day. The island is about the size of a rugby field the top of which is flat and is approximately 50 metres above sea level. Because the sides are vertical cliffs, access to the top is via a well worn penguin path riddled with burrows and lavatera plants. On the plateau is a small DOC hut that sleeps 2 but Chris and I decided to pitch tents on the rocky foreshore amid the stench of resident seals and thousands of noisy penguins and prions. We had to ensure we did not camp on any burrows or tread on the well camouflaged eggs of the black backed gulls but once settled in and after a cold snack for dinner, we found ourselves a prominent, but not too obvious, position amongst the rocks to await the arrival of the white-flippered penguins. They 'raft' in after the sun has set in groups of up to 10 at a time, perch on a rock or on the stony foreshore and preen themselves, oblivious to the 2 intruders amongst the rocks.
As the night gets gloomier and encouraged by the calls of the penguins already in the burrows, they start their 'parade' up the steep slopes. Sudden movements or noise would obviously scare them but despite that, their instinct is to make it home to their chicks, eggs or partner and accordingly they passed by me so close that I could have reached out and touched them. There are dozens of tracks inland from the shore but there are so many birds arriving that each track is a highway of single file penguins for hours on end. I had a bicycle headlamp attached to myself which allowed me to not only see the parade but kept my hands free and the lamp was not strong enough to frighten the birds.
We finally went to bed around midnight amid a cacophony of noise from both penguins and fairy prions. The latter arrive after dark and swoop around at great speed and at low levels often rustling one's hair in the process. They too nest in burrows alongside their bigger neighbours and also return to sea at dawn. Chris woke me around 4am in readiness for the "reverse parade" when the penguins return to sea for the day. It is just as spectacular as the arrival the night before but does not take so long. Firstly it is downhill from the burrows and secondly, any preening is done before they leave the burrows rather than on the shore. The calling noises from the burrows continues until after the sun is up by which time those penguins returning to sea have gone and relative silence descends upon the island.
On day 2 around lunch time, the helicopter arrived, landed on the rough clearing that Chris and I had made the day before, and disgorged Samantha Hayes and her cameraman from TV3, another Trustee, Hiroshi, a stills photographer, Bridgett and Anita from DOC. By narrating our previous night's experiences, Chris and I were able to help everyone set up in good vantage points in readiness for the second night's parade. It was a repeat of night one to the delight of us all. I happened to be with the stills photographer and because the camera flash is only momentary, it did not seem to worry the penguins and we gained some wonderful shots. TV3 gained some excellent footage which was edited down and screened one Sunday night after the news as the 'feel good' item.
All this was undertaken by the Trust with the long term aim of setting up a similar parade at Boulder Bay on Godley Head. Since Motunau Island is a DOC Reserve, it is not accessible to the general public but if we can establish a breeding colony at Boulder Bay, the resulting parade can be accessible to everyone. DOC is supportive but sadly the Christchurch City Council considers the rights of the bach occupiers at Boulder Bay a higher priority than the public and conservation values of the bay and therefore oppose it. Ironically the baches are built on public land but that means little to the Council. Watch this space!
The White-flippered penguin population at Harris Bay is increasing with each breeding season and this year is no exception. The numbers of eggs laid and hatched this year is up on last year and the chicks are looking big and healthy so there must be plenty of food in the ocean for the parent birds. Some of the chicks are almost as big as the parents so you can imagine the tight squeeze in the nesting boxes especially if both parents return to shore on the same night. They will continue to feed the young birds until such time as the chicks are big and strong enough to leave for the sea (fledging) and fend for themselves. This happens during the months of January and February.
Two interesting facts have been observed by our resident ornithologist, Dr. Chris
Challies. Firstly there is one female parent bird that is leucistic and two of her
six chicks from this and previous years have also emerged the same. Leucism is a very
unusual condition whereby the pigmentation cells of the penguin fail to develop properly.
This can result in unusual white patches appearing amongst the feathers or more rarely,
as a completely white bird. This condition differs from albinism.
The other interesting fact noted is that there has been an influx of little blue penguins from Otago into Harris Bay and although they have occupied some nesting boxes and laid eggs, these have yet to hatch. Have they been interbreeding with the White-flippered cousin or do they prefer their own ilk? Watch this space!