Another Knot post

 It's a while since I posted anything about Knot. The project keeps going with sightings coming in thick and fast from the North West and recently Orkney, Shetland and Iceland. We have been very successful at colour marking moulters and winterers on the Sefton coast however the group we have targeted and failed are the 2nd year birds which historically congregate on the Sefton coast throughout summer. This changed last week when we added colour rings to around 250 2nd year birds and recaught three that were ringed last autumn in Ceredigion. 

One day I hope we will have answered some of the following questions about these second year knot:

• Where do they winter, is it in the North West or elsewhere?
• Do they moult in future years on the Sefton coast or go elsewhere?
• Do they avoid Norway as a migration route like those we have marked as Adults do?
• Do any canutus spend their second summer here? 
• Do males and females do the same thing or is there a heavy bias in those summering in the North West? 

I think it's safe to say very few or no canutus were in the catch from the biometrics so recoveries of these birds in Africa is pretty unlikely.

Perhaps the biggest surprise for me was the proportion of adults we caught (about 10%). Those going to breed should have gone in early to mid May so these are, without a doubt, birds that are not going to breed this year. The weights of birds were too low to make it to the arctic and only around 15g heavier than the immature birds.

If these were birds in poor condition as a result of issues in since their last moult it would be likely their wing and bill measurements would reflect those of the adult wintering population. When I plotted wings against bills of adults we caught last week and those we caught in March 2018 it's clear there is a significant difference. The May birds were short winged and short billed. This suggests they're more likely to be males. 

I can see a few possible reasons for this although none really provide a complete answer:

• Females are more likely to breed in their 3rd year
• Non-breeding males and females spend the summer in different places
• Males are more risk averse than females and therefore abandon migration earlier
• The birds present in March include bigger birds that have moved in from the South

I've no doubt I've missed a few possibilities, suggestions as to what could be going on are welcome.

This made me think about whether the adults and juveniles are of a similar size, anyway, what's interesting is these small adults have marginally bigger bills than the immature birds. I would expect that the full bill length should have been reached by now. Wing lengths are not comparable because the immature birds are still flying on their first set of flight feathers.

In summary there are no answers, just questions. With just 3 already ringed birds caught these cannot really help answer any questions other than showing that juvenile Knot that used Ceredigion in September 2020 have moved to the Sefton coastline for the summer.

A huge thanks to everyone involved, particularly Sefton Council for access, all the observers for the huge numbers of colour ring sightings and everyone involved in processing and flagging the Knot.