Friday, 3 May 2013

Has Spring Been Cancelled?

A rather quiet period recently.    There are no signs of otters, and they seem to have gone.   I looked backed at all our observations over the last 8 years, a total of 69 events, to see if there was a seasonal pattern.   Of this total on 19 occasions we saw two or more otters together including a sighting of 5 otters in December 2010 (mother, 3 cubs and  male).   Below is a picture of the three cubs back then.

There is a seasonal pattern as can be seen in the plot below of sightings by month.

Otters are seen more frequently in the period October to March than they are between April and September (a ratio of over 2:1)  The pattern is even more pronounced for multiple sightings. If there is any bias in the data then it would be towards the summer months with much longer days and ease of observation.

I estimated the date of birth of the cubs we saw between January and March, by comparing their size to that of the adult mother from photographs in January and March and then using a chart of the rate of growth of otters in a paper by C Reuther (IUCN Specialist Group Bulletin Vol 16 Issue 1 11-16).  This information was for captive animals and it may be that wild animals grow more slowly, so that my estimate that the otters were born in late November and we started seeing them when they were 6 to 8 weeks old, might have been rather later than reality and their age understated.

 I also looked at the observation data to see whether there was any preference to the state of the tide, using data from the British Oceanographic Data Centre to provide the time of high tide.  Do otters prefer to fish on a rising or falling tide?   If there is a preference then it is not marked; maybe a falling off as high tide approaches.

Spring has been much delayed and there are very few plants in flower. The celandines and primroses are now flourishing but little else.   A small patch of  Great Woodrush is in flower, growing where I cleared away bracken 2 years ago and will soon be followed by Field Woodrush which is very widespread.  But little else, other than a solitary flower of  Wood Sorrell.

There are though some more hopeful signs.   I heard a cuckoo on Scalpay on 26 April, and other summer visitors have arrived - lots of meadow pipits, a pair of Common Sandpipers, a Wheatear and Stonechat.   In the garden there were queens of both  Early and White-tailed Bumblebees and the Hoverfly, Eristalis pertinax.

Last weekend there were some very low tides.  Moving a buoy anchored to two iron girders gave me a chance to poke around the kelps which was fully exposed.  Lots of Starfish and Velvet Swimming Crabs, and a small rather fat round fish which jumped out when I moved one of the girders.  It was away before I knew what was going on..

Then I fell over and got completely soaked.   The sea is cold!


  1. Don't worry about the otters: they are not far away! Since the middle of April we have had frequent (though not quite daily) sitings of them just offshore here - at the southern end of Ard Dorch township and less than a mile from you. I watched them for a good 20 minutes this morning.

    1. Very interesting. Mother and two cubs? Presumably by now the cubs are the same size or thereabouts as the mother. If I am right and the behaviour follows the Shetland observations by Kruuk, in the late eighties, then otters find calmer water, and eat smaller fish in summer. It was noticeable when they were up at the northwest end the mother was catching large fish, eg dogfish, though several were not fully eaten. The water gets shallower moving southeast on Loch na Cairidh.

      Looks like I will have to get the canoe out as the rocky area near in that direction is tricky.

    2. Yes, mother and two cubs.

      But today something new: Happened to be cleaning window when two otters belted past along the shore, northwards from here. Thought at first it was mother and one cub, but may well have been two adults: one pursuing the other. They were moving at speed, about 5 metres apart. I watched them until out of sight and they showed no signs of slowing down.

  2. Ooooh, that's exciting Gill!
    Maybe they have found a holt near you?

  3. Otters out of the breeding season don't have a permanent holt, rather they use temporary holts to rest up and if there is freshwater available, clean off the sea water. There are several such holts on the Ard Dorch coast - in the next week or two I shall survey south east down towards Dunan. In the breeding season a holt will be out of the way, often inland and well concealed.

  4. Hi Terry

    Your neighbour Steve gave me the link to your blog and I would like to make contact. Also a few comments about your blog. It is great to see your detailed observations.

    Eurasian otters don't actually have a strict breeding season though and cubs can be born throughout the year and they do actually use holts all year round. It is just that they have different holts and so may have moved to another one. This may be why you aren't seeing yours just now.

    I also think that because day length is so long in the summer and the weather better (?!!) they can be less obvious and will sleep more. They can sleep for so long too - we have watched one sleep for nearly four hours!

    Tides don't seem to make any difference unless it is in a narrow channel where the water is being pulled through on a moving tide. Low tides may be more difficult for us to spot them though if it is a wide shoreline.

    Normally cubs wouldn't be leaving the holt until about 10 weeks so I think you are right that captive bred ones may grow quicker.

    1. Grace

      Your comments are most welcome. (Grace with Paul run the International Otter Survival Fund based down the road in Broadford, undertaking otter conservation work throughout the world, see: I suppose I was trying to contrast otter behaviour with other mustelids such as badgers which occupy the same sett for years, and are very reliable when it comes to observation whereas otters don't use the same holt all the time, and are elusive. Other mustelids such as pine martens seem to behave like otters.