Goldcrest passage through Heysham 1985-99

Its mid-March and a spell of wet and windy westerlies come to an abrupt end.  Overnight a light north-westerly changes to a light south-easterly and the unlocking of the nature reserve gate at dawn is accompanied by two squeaking noises.  One comes from the heavens in the form of a northbound Meadow Pipit, the other from a nearby hawthorn bush.  The spring passerine migration season has started in earnest (with apologies to the two Stonechats seen the previous week).  

It is not always like that, however.  The bushes were silent during spring 1997 with only two individuals trapped and ringed.  Yet the 1996/7 winter itself was not a major problem for winter survival.   Why were 24 ringed in spring 1996 and only 8 in autumn, yet the two in spring 1997 were followed by 178 in autumn?  The ringing effort has been similar throughout with the exception of spring 1988 which has been discounted from any analysis.

Ringing totals during 1985-99

Year Spring   Autumn





Here the effects of the hard winters in 1985/6, 1990/1 and 1995/6 can be seen.  However, we have to remember that this species is a partial migrant.  Therefore a proportion of mostly young birds risk a 400+ mile journey from northern Britain to southern Britain/northern France undertaken as a series of short night migrations.  What appear to be mainly adults remain at or near the breeding grounds.  Therefore any differences in winter conditions between northern and southern Britain need to be taken into account.  A look at the 1995-7 figures throws up the following:

a)      Extremely poor survival by adults remaining on the breeding grounds during the 1995/6 winter

b)      Better survival by the mainly young birds which moved south (hence better than expected numbers in spring 1996 at Heysham).

c)      Poor weather during the 1996 breeding season in northern Britain, coupled with very low numbers of adults which had already bred once (therefore more ‘experienced’ if you can really use this term with a species which lasts for two breeding seasons at best),  was assumed to have led to atrocious numbers on autumn passage in 1996.   Indeed, there were only three actual sightings during the time-slot for birds of north-British origin in September and most of the paltry total involved a small influx of continental birds (& a Firecrest) in mid-October.    

d)      Predictably low numbers in spring 1997 as there were very few birds to return .  High survival rate amongst the non-migratory birds in winter 1996/7 coupled with a good.  1997 breeding season leading to excellent numbers in autumn 1997

A noticeable feature of springs 1998 and 1999 has been the earlier nature of the spring passage with hardly any April records in 1999!   This first came to notice with the presence of a Firecrest on Westgate for  7/2–8/2/98 only.  Searching for this bird revealed several Goldcrests already obviously on passage and a similar check of Heysham Obs. revealed similar small numbers of unringed (therefore not the wintering) birds.  Peak numbers appeared at the end of March with relatively few into April.  1999 again saw what were probably early migrants during late February and then a very large fall on 17/3, a week earlier than any sizeable arrival in earlier years.  Smaller numbers passed through during the remainder of March but there were virtually no records in April, even during good fall conditions in the first week, which produced sizeable numbers of Chiffchaffs and early Willow Warblers

Passing reference has already been made to continental birds.  These are presumed to originate from Scandinavia or perhaps the Baltic states but there is a possibility that some do come from further east in north-west Russia.  Their arrival is always ‘telegraphed’ by reports of Goldcrest falls on the east coast although, in some instances, a reflection of these falls does not reach ‘our side’ due to a change to westerly type weather conditions.  Arrivals have sometimes coincided with Yellow-browed Warblers or, in one case, a Pallas’s Warbler.  The only really large arrival of  birds of continental origin followed a huge fall on the east coast during the previous week and involved over 150 present (in a limited area of the nature reserve) with 50 trapped on 27/10/90, a significant proportion of the autumn ringing total.  The highest proportion of continental birds in autumn has already been referred to (1996). 

The effect of poor weather during the breeding season has already been alluded to with reference to 1995-7.  It was also apparent in 1998.   Spring 1998 should have seen the theoretically highest breeding population of the period under review.  Yet numbers during September were relatively poor after what, by common consent, was an appalling breeding season in northern Britain.     

Retrap data and ringing recoveries reveal that the passage of birds of north-British origin is leisurely, involving quite a bit of lateral movement (e.g. Calf to Heysham and Walney to Heysham movements during the same season). However, one recovery took this to extremes and reminded Spurn observatory workers that you cannot be too presumptuous re-the origin of presumed ‘in-off’ (the sea) Goldcrests!  It was ringed at Heysham Obs. on 27/9/97 and controlled at Spurn on 15/10/97.  There have been winter-period recoveries from Dorset (2), Greater London, Staffordshire and breeding season recoveries from the Mull of Kintyre and Northumberland.  One of the most fascinating, however, was ringed during a strong north-easterly airflow, which produced Siberian Rubythroat and Red-flanked Bluetail in Dorset and Leicestershire respectively.  Surely of continental origin, it was ringed on 18/10/97 and, helped by the overnight tailwind, controlled on Anglesey during the morning of 19/10/97.

Hopefully this short article has revealed the interesting information, which can be obtained through operating an observatory-type ringing station.  This type of operation is particularly helpful in the study of partial migrants such as Goldcrests and Robins where very little that is meaningful can be gathered from casual observations.  Indeed, how many readers realise that Robin is the most consistently common medium to long distance night migrant through Heysham from late August to early October?   An article will be prepared for a forthcoming Newsletter.  

Pete Marsh  (September 1999)

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