Tuesday 22 December 2015

Irish Bird Ringing Data - Thrushes

Since 1975, a total of eight species of Thrush have been ringed in Ireland.  Those include the resident breeders of Blackbird, Song Thrush & Mistle Thrush, the rare breeder, Ring Ouzel and the wintering thrushes of Fieldfare and Redwing.  There are also a couple of very rare species to have been ringed -  White's Thrush and  Grey-cheeked Thrush.  There are a further three species of Thrush that have been recorded in Ireland which include - Hermit Thrush, Siberian Thrush and Swainson's Thrush. 
Three (4) White's Thrush have been trapped in Ireland, with the first at Copeland Bird Observatory (CBO) back in 1993.  The only other ringing records came in 2009 but the data doesn't quite match - certainly two but potentially three were ringed in Ireland in this year.  This is very impressive for an eastern Thrush, with only 12 ringed in the UK and Ireland since 1909. 
Four Grey-cheeked Thrush have been ringed in Ireland, coming in a 10 year period between 1982-91.  The bird caught at Cape Clear in October 1982 was a first for Ireland.  A total of 16 have been caught in the UK and Ireland since 1909. 


The Blackbird is one of the most recognisable species in Ireland, which frequent gardens up and down the island.  Come winter we receive a large influx of birds from northern Europe, which join our resident birds - a few of which will move south for winter.
The Scandinavian birds tend to differ from our resident Blackbirds, often larger, heavier and can have slight differences in appearance i.e. the bill colouration.
The graph below shows a decline in the numbers being trapped before it levels off over the last 20 years.  Copeland BO shows a steady decline in the totals trapped at the Observatory below. 

  1956-65          1966-75          1976-85          1986-95          1996-05
1,235                996                  499                  343                220

The suggested explanation for the decline in numbers caught at the Observatory over the years is the ever increasing bright lights of Belfast and the mainland.  With this, this lighthouse no longer attracts the birds that it used to.  This may account for some of downward trend across the board but probably limited to only a couple of the coastal ringing sites. 
Since 1977 there have been 12,013 trapped in the north and 13,366 in the south.  The most productive year in Ireland was 1985 with 1,429 and the least 2008, with 394. 

 Given the number of Blackbird recoveries, I have separated them into three maps.  The first shows the birds coming in from Britain, the second from Europe and the third, birds leaving Ireland.  The data presented includes only a selection of the recoveries, with many more not available to me.  Between 1983-86 for example there were further recoveries not included - 13 Norway, 2 Netherlands, 3 Denmark, 3 Sweden and 1 Germany. 
A few of the most distant movements include birds to Latvia, Finland and northern Norway, some moving over 2,000km.  Some of the key sites during migration include Helgoland, off the Germany Coast and the Lincolnshire/Yorkshire coast, particularly Spurn Point.   
For both the birds coming in and going out, the majority fit well within the general south west/north east movements, with only a few birds moving in different directions. 
Unfortunately for the Blackbirds, most of the recoveries come from dead birds - cats and cars are the big killers. 

 Blackbirds coming into Ireland from Britain
Blackbirds coming into Ireland from Europe
Blackbirds leaving Ireland

Ring Ouzel

The Ring Ouzel is a rare breeder in Ireland with only a handful of pairs each year in the mountains of the north and west.  It is more commonly seen on passage during the spring and autumn with c25-50 birds a year.  The majority of these records come from the south coast around Cork and Wexford, with a few records every other year in Northern Ireland.
I was fortunate to get my hands on the bird pictured above last year - the first trapped in the north since 2000. 
The graph doesn't present much in the way of trends but the birds were certainly caught on a regular basis in the late seventies to eighties.  At Copeland BO they trapped 21 Ring Ouzel from 1954-1984 and only two in the thirty years since - including the bird above.  Only 17 have been caught across Ireland since 1977 and apparently no recoveries. 


These Nordic beauties spend the winter in Ireland roving around in mixed flocks with Redwings.  The species was traditionally targeted at roost sites and orchards but there has been little focus on the species in recent years. 
A total of 2,432 Fieldfare have been ringed in Ireland since 1975 - the most productive year was in 1985 with 495 birds, 399 of those in the south.  I can't comment on the weather conditions in Scandinavia in 1985 or ringing effort in Ireland but it was also the most productive year for Blackbird, Redwings and Song Thrush.  There were no birds caught in 1994 and 1998. 

The recovery map below is quite misleading in that it would have you believe that these birds are passing through Ireland and wintering in southern Europe.  None of the movements into southern Europe go directly from Ireland but are during subsequent winters, having returned to Scandinavia to breed at least once.  These birds have, for some reason, chosen pastures new to spend the winter months, perhaps simply wind direction at the start of migration. 
A ringing site in Lucan, Dublin during the 1980's was very productive and accounts for 9 of the 17 birds ringed in Ireland that were recovered elsewhere.  These include - 3 to Finland, 2 to Italy, 3 Norway and 1 to France.   This site has managed a number of recaptures of birds over many years, proving some birds are site faithful. 
The species is quite different from Blackbird for example, because few of these birds are caught at coastal bird observatories, but rather, further inland in breeding/wintering locations.  This, may be in part, due to the fact the birds migrate in late autumn when many of the observatories have closed, particularly in Scandinavia. 

Fieldfare recoveries into (green) and out (red) of Ireland 


In Ireland, the majority of the Redwings that hit our shores in winter are supposedly of the Icelandic race 'Turdus iliacus coburni' with a few of the nominate Northern European race ' Turdus iliacus iliacus'
Despite being similar in nature and the obvious spike that correlates with Fieldfare, the two graphs differ, with Redwing fluctuating much more. 
A total of 4,519 have been ringed in Ireland since 1975.  As mentioned above, 1985 seen the most trapped, with 488 and the lowest was only 20 caught in both 2000 & 2001.  I probably would have expected the capture rate between Redwing/Fieldfare to have been greater than roughly 2/1. 

The ringing recoveries show a greater number of the nominate race coming into Ireland but this is probably down to the limited number of ringers in Iceland.  A couple of the Icelandic recoveries are very nice as they refer to birds ringed in the nest, so their birth location is known.  Some of the recoveries out of Ireland are far flung with Finland, Portugal, Poland and Cyprus.  The Portuguese and Cypriot recoveries come in subsequent winters and not directly from Ireland.  It might be possible to presume that the two birds wintering in Portugal are of the Icelandic race and step stone through Ireland - particularly the bird ringed at the Bridges of Ross, Clare.  The bird in Cyprus being so far east, is more likely from the nominate race.  The greatest distance travelled is a minimum of 2,943km from Russia. 
Redwings tend to frequent bird observatories more so than Fieldfare but there are many more of them and they are easily attracted to tape lures. 
Again, not all the recoveries are available and there are at least another 8 from Iceland, 2 Norway, 1 Finland, 1 Netherlands and 1 Fair Isle, Shetland.

Redwing recoveries coming into (green) and out (red) of Ireland

Check out Peter Alkers blog -'Two in a Bush' for nice comparisons of the two races

Song Thrush

A resident breeder with an influx of birds from the continent for the winter.  Similar to the Blackbird, the continental birds can appear different from our resident birds, again often larger & heavier, with more greyish feathering above and whiter below.  Unfortunately this is yet another species that is declining greatly and this is reciprocated in the ringing totals.  It will be interesting to see the ringing results for 2015, as it looks to have been a better breeding season going by the number of juveniles we caught personally. 
A total of 8,401 Song Thrush have been ringed in Ireland since 1975, again 1985 was the best year with 420 and the worst was 2002 with 37. 

The birds coming into Ireland seem to come in two main directions - a westerly passage through east England via Germany and Denmark and then a south west movement pouring in via the Northern Isles of Scotland, possibly from Scandinavia.  There are also then some probable Scottish breeding birds than winter in Ireland.  There is at least one Norwegian recovery but I do not have the precise details of this one.  The bird recovered in Ponferrada, Spain is interesting and is presumably a bird that passed through Ireland (Great Saltee) in late autumn to winter in Iberia. 

Song Thrush recoveries coming into (green) and out (red) of Ireland

Check out Peter Alkers blog -Two in a Bush for nice comparisons of the two races

Mistle Thrush

A large resident Thrush with a handful of immigrants during the winter.  There is a steady decline in the numbers being caught, which correlates with the decreasing populations nationwide.  The species is not easily caught, as they tend to stick to the high trees and open ground.  The best opportunities are around fruiting trees/bushes in winter or chicks in the nest. 
This is one of the few species where there have been many more ringed in the north - 770 than south - 338 since 1977.  In 1987, 92 birds were trapped in Ireland, falling to the lowest catches of 3 in 2012 and 2014. 
There are apparently no recoveries of this species coming into or leaving Ireland. 

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