16 Sep 2015

16 Sep 15 - Was Last Week The Warm Up Act?

A recent Post covered a big movement of 888 Siskins moving North across South Haven on NE winds on 9 Sep 15. The winds then swung more Easterly (or South Westerly) which are poor winds for Vis Mig at South Haven. But the Siskin Vis Mig continued further East at Christchurch Harbour (CHOG) with 920 East on the 11 Sep & 820 East on 13 Sep. The forecast for this morning was light NE winds. I hadn't really picked up on the weather for a Vis Mig watch as I was more concerned about a wet front arriving from the sea. I had expected that front to have arrived by breakfast time. But I headed out, half expecting to be quickly retreating to the Brands Bay to shelter from the rain, whilst checking the rising tide. But it was dry, with threatening clouds. I started with a seawatch hoping that something might be moving/relocating after the SW gales from the previous day. But it was a long shot. However, I noticed a few parties of Siskins started to appear from 08:30 with good numbers of Swallows also moving. So given the light NE winds, I switched plans to a Vis Mig watch. By the time I had got to the Vis Mig viewpoint at 09:20, I had seen 135 Siskins going North. Time to watch & count properly. It started off steadily. Parties of Siskins coming over every few minutes & heading North. The Swallows were moving on a much broader front, with the bulk moving over the water on a 1/4 mile either side of the Vis Mig viewpoint. I clearly under counted the Swallows as my scans of the water, broke off every time I heard Birds overhead calling. Even so, in the two hours I was counting I saw 1232 Swallows moving North.
Siskin: A typical part of one of the many flocks moving this morning
But the clear highlight of the day was the Siskins. In the two hours from 09:20, I had a stunning 2071 Siskins heading North. At this point, I retreated to the car as it started to drizzle. With the threatening clouds, I was expecting worse to come. But it cleared after twenty minutes, so I headed out again, but got side tracked with a mixed Tit & Warbler flock, which also contained a Spotted Flycatcher. As I was generally Birding, I had another 217 Siskins heading North. The final total for the morning was 2423 which appears to be a new UK day record for Siskins.
Siskins: Unfortunately, they are mainly moving about 50 metres from the best viewpoint. So to try & get closer for photos, means I'm not going to be able to see all the movement. Hopefully, I will get a chance for better photos, when I get some Vis Mig company from Graham Armstrong
It's well known to Vis Miggers that Birds will coast into the wind providing it's not too strong, i.e. the follow the coastline & fly into the wind. They get lift in the same way that aeroplanes do. So that explains why I need a Northerly based wind for South Haven to work. Birds happily head into the wind along the North-facing Studland Peninsula.
Siskin: I need to get a NE wind when Graham is also at South Haven to do the counting, while I try & improve on the photos. Also a day with blue skies, rather than 7/8 grey cloud cover will be a big improvement
After my good Siskin movements last week, I have been thinking about where these Siskins had originated. First I had a play with the interactive analysis maps function on the excellent Vis Mig site. A quick play gave this excellent analysis map of the movements of Siskins since the start of August to 16 Sep. Think this link should work, even if you aren't logged onto the Vis Mig site. This shows the biggest movements have been in Dorset, followed by Sandwich Bay, Kent. But why should Dorset & Kent be so good. Clearly, these counties are both great & related: I now live in Dorset, but was born in Kent. But that seems to be purely coincidence & had to be ruled out. I needed some better theories. There seemed to be three options: 
  • Siskins moving out of the SW & coasting
  • Siskins moving South & hitting the coast, followed by coasting into the wind
  • Siskins arriving into Dorset via Normandy.
The latter isn't as daft as option as it sounds, as that is the route many Chaffinches take each year. A significant percentage of the Chaffinches moving South along the European coast, then seem to track up through Normandy, across to the Dorset coast, with many ultimately ending up in Ireland. But not having any feeling for which option was most likely (but quietly liking the French Connection), I asked around. Looks like that isn't the answer. 

This was the response from the ever helpful Clive McKay who is the UK Trektellen coordinator. I hope Clive won't mind me repeating his comments here:-
I’ve been posting on the vismig group since July about the large number of Siskins moving over the summer this year – starting in Scotland. The story is pretty straight forward – last autumn/winter was the best coning year for spruce in N Britain in so called “living memory” of various folk that I’ve spoken to (i.e. since at least since the last big cone crop up here in 2010/11). The forests appeared gold last winter rather than green - cones rather than leaves. So an “irruption” of northern birds south was on the cards, as last happened in 2011. Numbers this summer were higher than in 2011, so a big movement seemed likely. But with lots of winds in the easterly quarter recently, it seems the moving birds have been slipping through inland on a  broad front in small numbers, rather than being concentrated on the east coast. East coast sites require westerly winds to “work”, and I’ve been frustrated that there have been very few potentially good days at Carnoustie – as I was hoping to break my UK Trek British record of 2,200 from 7 Sep 2011. No record breaking counts at the east coast sites so far, but numbers have started to appear at the south coast (including CHOG and Sandwich) and your birds fit in well with this pattern.
This has been nicely confirmed by Paul Morton, the main man behind the Birds of Poole Harbour website. Paul is one of the Sound Approach team that has been doing night time recording over his garden & elsewhere. Every now & then he has put interesting recordings on the Birds of Poole Harbour website. Nick Hopper, the other member of the local Sound Approach night time team, has been recording at Portland Bird Observatory & his recordings appear on the Obs website. Paul has said this evening that he has been leaving the kit to carry on recording for a couple of hours after dawn, which seems to backup Clive's comments:-
The other thing I've noticed this year is the number of Siskin moving over my house so early in the autumn which I assume are birds making their way to the coast, and are then counted by the 'vis-miggers'. After a nights sound recording in the garden I often leave it running into the first couple of hours of daylight and when I listen to an hours worth after dawn Siskin calls almost become white noise with birds passing over (often distantly) every few minutes.
I must admit I didn't think I would get an answer to the question as to where the Siskins are coming from, so it is great to get this feedback from Clive & Paul which seem to support it.
Goldfinch: This cheeky Goldfinch tried sneaking through in one of the Siskin flocks
Unlike the first Vis Mig watch, there was a good selection of species on the move today. During the two hour Vis Mig watch, I saw the following species (all of which moved North): Sand Martin 10, Swallow 1232, House Martin 2, Tree Pipit 9, Meadow Pipit 291, Grey Wagtail 15, Pied Wagtail 1, Chiffchaff 6, Carrion Crow 6 (local movement? but the local Crows don't often cross the Harbour mouth), Goldfinch 3, Linnet 4, Redpoll 17 & of course, Siskin 2071.
Tree Pipit: Great to finally get to see a few Tree Pipits, they have been noticeable on the patch by their absence until late August. But when I checked back, most of my Autumn Studland/Ballard records are in September
One of the great local specialities of the South Haven site is seeing Vis Mig of species that normally seem to move in small hops between bushes. At South Haven, they run out of bushes & then have to cross the 200 metres to the nearest cover on the Sandbanks side. So we see Vis Mig of species that generally perfer to move in small hops like Warblers, Tits and Crests. I suspect this movement often gets missed at many Vis Mig sites. But it creates its own problem for us. The stronger species like the Finches, are mainly in flight when they past over the last bushes. Thus, they already have a good forward speed to cope with the more exposed winds at the Harbour mouth. Even if they stopped for a brief rest in the last bushes, they they are strong enough to be able to quickly get back up to speed to make it across. But the weaker fliers like the Warblers, Tits and Crests are always starting from the last bushes & trees. Thus, they are battling from a stationary position & also trying to climb to get over the Harbour mouth. Frequently, we see these species start & twenty or thirty seconds later, see the turn & rapidly head back into the bushes. So I end up having to keep a longer watch on them to see if they really make it or just turn back. Today was a typical day. There were at least ten Chiffchaffs trying to cross the Harbour mouth, with six ultimately making it across. But maybe twenty or more failed attempts.
Chiffchaff: They often make several attempts before the make it across

1 comment :

  1. Well my UK Siskin record lasted for one day. On 17 Sep 15, Sandwich Bay had an astonishing 4520 Siskins North in 6 hours. Hats off to the Vis Miggers. Details here

    http://www.trektellen.org/count/view/440/20150917

    Steve

    ReplyDelete