Today we happened to visit the “nursery”. There were seven young ones – four newborns and three first-year babies. The smallest one was still rather clumsy and popped to the surface like a little cork. The bigger ones were darting about like little torpedoes amongst other members of the group. All were supervised by their (presumed) mums some of whom were conveniently well marked individuals. There was a lot going on. We had a field day!
Dolphin galore! Note the newborns with the foetal fold marks still visible. (photo: Caye)
Of course I’m talking about Chilean dolphins here. We were on our second round of surveying when we came upon this large group with calves. We always take extra care when working around mother-calf groups to avoid disturbing them. Today’s dolphin mums and calves were busy minding their own dolphin business, and didn’t really seem interested in or bothered by our presence. So we got to watch and photograph them from a respectful distance, except when they briefly came to check us out and passed as little grey shadows underneath our boat (underwater visibility was poor with less than 2 meters). We know from our long-term study on Chiloé that dolphin group sizes tend to increase as the summer season progresses (and more babies are born). Mother-calf pairs often form distinct groups as they are bound by a common cause. There’s not really a fixed area for a dolphin “nursery”. The little one has to go where mum goes, and mum goes where the food is. Ideally the food should be easy to get in an area that is safe from predators. Food supply should be reliable and plentiful so that mum and calf do not have to travel much. Today’s area seemed to fit these requirements very well.
Two mother-calf pairs surface almost in unison. Both mums bear subtle identification marks on their dorsal fins. The sea appears green because the dolphins are close to shore and the coastal trees are reflected on the water’s surface. (photo: Sonja)
Dolphin mothers have to feed regularly to nurse their young and maintain their own body condition. So they need high value areas that can provide for their needs. In poor light a typical Chilean dolphin can appear black, short and stocky - or in local lingo: negrito, bajito y gordito. Chilean people have a good sense of humour, and some have pointed out with a smile that this is also an apt description for many of the locals :-). In a typical expression of cheeky endearment Poli, one of our Chilean team members, calls Chilean dolphins “gorditos lindos”.
Depending on the light Chilean dolphins can appear almost black (here an adult with marks on the dorsal fin and a calf in front). Hence, in English they are also known as “black dolphins” but this is a misnomer as their true colouration consists of shades of grey with some white parts. (photo: Sonja)
We have noticed that the local dolphins appear a bit bulkier than those off Chiloé, and are a lot more interactive with our boat and with each other. Yesterday we saw more dolphin leaps in one day than we would see in a typical field season in southern Chiloé. Our team members have observed Chilean dolphins in different areas and we all notice this difference in behaviour of the local dolphins which just seem “easier and friendlier” to work with. Could it be that life is a lot harder for our more familiar “fome” (boring/ difficult) dolphins in our long-term research area on Chiloé than it is for the ones we’re currently observing? Of course photographs and impressions in the field are not enough to establish how well the dolphins are doing or what they are feeding on. Other methods are needed for such studies – more about that in a different post.
Some Chilean dolphins are more fun than others. These two are showing off…. (photo: Sonja)
At least today’s mother-calf pairs seemed to be doing well. We were lucky enough to watch them both resting and feeding. Or rather, we watched the dolphins’ food trying to escape being eaten. We also had some helpful assistants who brought the dolphins’ presumed prey to the surface for us to see more clearly. South American terns were feeding right next to the dolphins and showed off what both species (and many other birds and even some sea lions) seemed to be feasting on.
This South American tern very helpfully sampled the available dolphin food. (photo: Sonja)
So at first impression, we’ve found a bountiful place for dolphins and other marine creatures. We did not expect this as this dolphin habitat is next door to (but does not overlap with) a busy fishing port, a wood chip factory, lots and lots of aquaculture farms (both mussel and salmon) and an important shipping route. It’s like having an idyllic picnic spot next to the Panamerican highway….
Chilean dolphins attacking a school of sardines. (photo: Caye)