Meisen Wood: September Slips By

Ringers:  CS and EB

Sound: various

Temp: from 6C to 34C

September has rapidly slipped by, again. We are amazed, each year, how fast September’s time gracefully slides from the heat of summer to Keats’s season of ‘mellow fruitfulness’. September is a fluid intermezzo between summer and autumn; guests of summer depart and pass through, guests of winter begin to arrive.  The Blackcap’s song fades into migratory tac-tac calls, the Chiffchaff’s onomatopoeic calls are uttered less and less and then are gone to be replaced by the the pink-pink calls of Chaffinch.  This passage of birds is partially reflected in our ringing totals.

Species	Ringed	Re-trapped	Total
Blackbird	4	1	5
Blackcap	6	0	6
Blue Tit	85	26	111
Bullfinch	2	0	2
Chaffinch	1	0	1
Chiffchaff	4	1	5
Coal Tit	20	3	23
Crested Tit	1	1	2
Dunnock	16	2	18
Firecrest	14	0	14
G S Woodpecker	0	2	2
Goldcrest	6	0	6
Great Tit	241	95	336
Greenfinch	0	1	1
Jay	2	0	2
Marsh Tit	6	6	12
Nuthatch	10	10	20
Robin	18	1	19
Short T Treecreeper	8	2	10
Song Thrush	1	0	1
Spotted Flycatcher	1	0	1
Wren	0	1	1
Total	446	152	598

Not shown in the table is that the totals are dominated by juvenile birds, reflecting a productive breeding season in most of the captured passerine species.  From ringing Great Tit, Blue Tit, Pied Flycatcher and Nuthatch pulli in our nest boxes we know that these species had a good breeding season, locally at least, as our figures were our best to date.    

The Coal Tit and Short-toed Treecreeper numbers are the best September figures we have had.  All the Coal Tits were juveniles and certainly represent juvenile dispersal (that is the movement of juveniles away from their natal area into new areas and probably new territories).  This conclusion is backed by the German Migration Atlas which states that most German adult breeders are sedentary with recoveries greater than 10km virtually unknown.  Though a caveat here is that in September and October, in some years, large numbers of juvenile Coal Tits arrive in Germany from the Baltic States – did any of the captured Coal Tits originate from that area of Europe?   

The Short-toed Treecreeper figures probably reflect juvenile dispersal, though adult – juvenile differentiation is difficult after post-juvenile moult is completed.  Ten newly ringed Nuthatches probably reflect post juvenile dispersal too.  Most of the re-trap Nuthatches were adults which we know from our ringing records are territory-holding local birds; they were frequently caught in close proximity to the juveniles thus a possible hypothesis is: the adults were escorting/chasing the dispersing juveniles off their territory.

Fourteen Firecrests through the month is a typical figure for us.  These miniature birds, but a few centimetres long and weighing a tad over five grams, migrate through here in early autumn.  A Firecrest ringed by us was controlled on the Channel Islands some kilometres distant.  No retraps of this species was semi pleasing too as through the spring and summer we have been frequently capturing two males, of two breeding pairs.  Firecrests are frequently in the vanguard of Goldcrest migration; will that be the case this year?

 

With the Great Tit and Blue Tit figures conclusions are more difficult to make and potentially complex.  They probably reflect a genuine mix of dispersal, partial migration and full migration but more on this in a later piece.

Considered caution is a cognitive skill that ringers exercise in relation to such aspects of ringing as: exactly how to extract each bird from the net; identification of a species that is rarely captured; assigning age and sex to an individual; and initially deciding if a re-trapped bird could in fact be a control. 

At one point during the month we were both hesitant as to whether, or not, we had a control Marsh Tit.  Tentatively we concluded that it was a bird with one of our early ring sequences.  The computer said we were correct.  The Marsh Tit was the twenty-ninth bird we ringed in our first ever ringing session here in February 2015.  Further this was its first recapture event; yes, that stimulates several questions but no explanations I’m afraid.  Back in 2015 this bird was aged as an adult meaning this individual is at least six years old.  From ringing studies the oldest German Marsh Tit was 11 years of age. 

Extracting Blue Tits can sometimes be awkward.  But in one of this month’s sessions an easy looking extraction proved to be otherwise: legs freed, wings freed so the remaining few net strands should just slip over the bird’s head and voila - that would be that, but that was not happening.  Careful examination of the bird’s nuchal nape band revealed a goliath of a tick around which several net strands were wrapped.  A judicious cutting of these strands completed the bird’s extraction.  Back at the ringing table the tick was removed and its measurements taken: length 14mm, width 6.5mm and weight 0.1g; it made a satisfying pop when destroyed.

Ticks are common parasites on birds here.  We particularly encounter them on Great Tits, Blue Tits, Chaffinches, Greenfinch and Blackbirds; we record their numbers and location.  Our ringing kit includes forceps for their removal and destruction.  This is partially for the health of the birds but also has a component of self preservation: we don’t want ticks in our garden, or at least only in low numbers.  We frequently find them on ourselves and given that they are vectors of a few nasty diseases we have no qualms in eliminating them. 

Caution needs to be exercised too when extracting garrulous Jays who can inflict pain and draw blood from a ringer’s fingers.  Each autumn we catch a few of these colourful corvids: this September one adult and one juvenile.  In late summer, early autumn we watch Jays with bulging crops excavate shallow depressions, with a few savage blows from their stout bills,

into which they then regurgitate an acorn.  We watch the red squirrels bury acorns too. Research indicates that both species remember where they have buried their treasure ready for consumption during the food scarce times of winter.  They may remember the location of some but by means all the acorns.  An annual spring task is plucking oak saplings from the meadow – this year that was over 300 freshly germinated oaks and maples.  Our plucking, like much of conservation work, prevents succession and our meadow becoming a wood. Though within the wider wood this means the oaks benefit through this method of seed dispersal. 

This year the acorn crop is much less than last year’s when there had been a super abundance of acorns.  This acorn deficit probably explains the near constant movement of Jays over Meisen Wood and along the Teutonburger Hills we have been witnessing this September.  On fine days there has been a clear and distinct migration of Jays flying from ESE to WNW.  CS on five mornings watched for an hour, those birds flying over our restricted view of the hills, his total was 771 Jays.  So the final total will have been huge.  Migration watch points north of here and in the Netherlands have recorded numbers into the thousands which suggests a major failure of their acorn food source somewhere and probably over a large area too.  The migrant Jays were flying at a greater height with a purposeful direction, compared to the lower flying local acorn hunter-gatherers.  They passed over in loose squadrons: 10 here, 17 there, then 39 over there but it was a constant passage just like September is a constant connection between seasons.