 |
|
|
In this year we decided to change our methods of orca observations. Land-observing team was disband, but instead we worked in two boat at sea – one for photoID and biopsy, and other for acoustics. This was able because we received a grant from Rufford Maurice Laing Foundation, which widened our abilities to study orcas. Comparing data from both boats enabled us to reveal new facts and patterns.
We began this season on June 21. Our house successfully survived Kamhatkan winter, which was very snowy. After several days of repairs and maintenance we finally went out to sea. There were no orcas for two days, and only at June 27 we heard familiar calls in the hydrophone. We defined the direction – cape Opasny – and went there, and soon found a small group feeding near Opasny cape, which soon left to the south. We met this group for
 |
some more days. On 5 July, following this group, we encountered a big multigroup aggregation of several tens of orcas. Some of them were resting, and some socializing, often making sounds in the air. We observed two females lying on the surface while their calves were playing around. Then a big male joined them, somebody from this group made a specific sound, and they started traveling. We observed other groups for a long time, but it was very difficult to work with orcas in such situation, because animals were mixed and all made different things. |
The next surprise orcas prepared for us on July 12. We met a big multigroup aggregation again, and they all together went by the island to the south towards cape Opasny. There they started to feed together around our boat, aometimes so close, that we feel spray from their blows. We distinctly saw Atka mackerel, jumping out of their mouths, and even made photo of a sea gull, who have stolen one fish. It was a first documented evidence that Kamchatkan orcas eat Atka mackerel.
| During this season we often observed such multigroup aggregations, and sometimes there were the same animals for several days. Rather often we met aggregation with our familiar male Hooky and Humpy – juvenile with a strange hump on his back. During this season we often observed such multigroup aggregations, and sometimes there were the same animals for several days. Rather often we met aggregation with our familiar male Hooky and Humpy – a juvenile with a strange hump on his back. |
|
It is difficult to work with such multigroup aggregations, but we noticed an interesting phenomena because of them. We noted that slowly travelling killer whales sometimes started to move very quickly, even porpoising, and then joined some other group which was foraging. On five occasions we made acoustic recordings of vocal exchanges between quickly travelling and foraging animals. The number of calls during fast traveling was significantly higher than during every other behavioural category. Together with behavioural observations, these data could be explained in several ways. One suggested hypothesis is that foraging killer whales could be calling for other conspecifics to join them. Attracting conspecifics could be a strategy for increasing the feeding success of the caller: the approach of other animals could chase fish back towards the caller and, thus, increase its probability of a catch. Attracting conspecifics could also be useful if the number of animals in a group is not large enough to herd the school of fish. This calling could also be used to attract closely related kin, because killer whale pods consist of animals which are closely related to each other. Another explanation is that traveling killer whales could announce their presence to foraging ones by calling.
Besides these findings with our familiar orcas, we also met totally unknown orcas. On August 13, we heard calls in the sea. We found orcas 15 km from the shore, and they were moving to the sea. Their appearance and sounds was unknown to us. We followed the until we were 30 km from the shore. We also met Dall’s porpoises who swam near orcas without fear. We also met a group of Baird’s beaked whales who prefer to keep far from the shore.
On 1 September we again heard unknown calls, but now they were even more strange. We found the orcas – there were only two animals, and by appearance they looked like transient, mammal-eating orcas from Northeastern Pacific. They had sharp dorsal fins and big saddle patches with bites of a small cookiecutter shark. Thus means that may travel to warm, even subtropical waters because this shark lives only in warm waters. Many species of whales and dolphins that live or travel through warm waters suffer bites from this shark; killer whales appear to be no exception. Transient whales are usually silent, but these two were calling almost all the time, like if they were calling for somebody. Unfortunately, we couldn’t follow them longer because of the weather.
On 3 September we returned to the city. But we saw orcas once more this year. We helped to guide the group of whalewatcher tourists from Japan, who came to Kamchatka especially to see our orcas. On the second day we met a group of orcas, and they made a real performance for the tourists – with breaches, spyhops etc. On the third day we met a playful group of Dall’s porpoises who bowride on our ship’s bow wave. Tourists were very happy to see all these wonderful wild cetaceans.
|
top |
|
