Why no Woodpeckers in Ireland (1 Viewer)

[breffni]

GSW fledged quite a while ago, way back in early-mid june, so any juv has had plenty of time to move. The key point about juvs is if they're dependent or not, i.e. being fed by an adult or giving begging calls.

I'm not sharp on irish geography - how close is the second juv to the first?

Rumour I've heard, from people who'd know, is that a couple of pairs have been breeding for several years anyway.

Any idea how soon after fledging do juvenile GWS disperse? And what are typical dispersal distances? (web has not much literature on this...)

The distance is about 20 miles (http://maps.google.com/maps?f=q&hl=...37355,-6.446228&spn=0.674094,1.430969&t=h&z=9)


The rumour has been going for a few years now - it would make sense to surpress a breeding site from a conservation point of view.

 

[KnockerNorton]

Any idea how soon after fledging do juvenile GWS disperse? And what are typical dispersal distances? (web has not much literature on this...)

because there isn't much info. They probably disperse about 2-4 weeks after fledging. Only 17 pulli have ever been recovered, up to 54 km away (only 3 moved >20km), but this doesn't mean much as the sample is so small. We know that most birds of other species don't disperse far (most under 20km for other sedentary species) but some individuals of each species do make much bigger movements. Juv GSW in autumn have been recorded moving >150km, but this is already after post-juv dispersal. As i said, 200,000 GSW fledge in Britain each year, so statistically some of those will be moving large distances, and some of those will be to ireland. It will be tiny numbers, but a tiny fraction such as 0.1% of that total is still 200 birds.

The distance is about 20 miles (http://maps.google.com/maps?f=q&hl=...37355,-6.446228&spn=0.674094,1.430969&t=h&z=9)

oh ok, cheers. If they were in the same wood or soemthing, that'd be different (though still not conclusive), but 20 miles is enough to make them independent obs and events, i think.

The rumour has been going for a few years now - it would make sense to surpress a breeding site from a conservation point of view.

I'm pretty sure the rumour is true, but I think there's a lot that isn't being revealed. Origins could be one of them.

The thing is, breeding GSW and fledgling GSW are very easy to find, so if they're not being found then either people aren't looking, or they're not there.

 

[breffni]

because there isn't much info. They probably disperse about 2-4 weeks after fledging. Only 17 pulli have ever been recovered, up to 54 km away (only 3 moved >20km), but this doesn't mean much as the sample is so small. ... Juv GSW in autumn have been recorded moving >150km, but this is already after post-juv dispersal. .

So all juv birds have left parents nad are living independently four weeks after fledging? any data to support that?

Is there any evidence ever of a recently fledged juv travelling over 100 km of open sea? Surely this would be a very poor adaptation and juvs with a tendancy for such long dispersal over sea would be much less likely to survive than more conservative birds.

As i said, 200,000 GSW fledge in Britain each year, so statistically some of those will be moving large distances, and some of those will be to ireland. .

Not enough data for statistics with only 17 records. Do you have a source for the ringing report - i can't find anything...

oh ok, cheers. If they were in the same wood or soemthing, that'd be different (though still not conclusive), but 20 miles is enough to make them independent obs and events, i think..

why is 20 miles over land too far and at least 100 km over sea not too far?

I'm pretty sure the rumour is true, but I think there's a lot that isn't being revealed. Origins could be one of them..

While someone may be releasing autumn juvs in ireland, i think it is very unlikely that anyone would be releasing birds only six weeks out of the nest in july.

The thing is, breeding GSW and fledgling GSW are very easy to find, so if they're not being found then either people aren't looking, or they're not there.

Unlike Britain, there are relatively few birders in ireland and the general population are unfamiliar with the call or knocking of peckers. If a couple of pairs were breeding somewhere in the very extensive wicklow forests they could easily go unnoticed until one turned up at a bird feeder...

Its important to keep an open mind and without a nest it is impossible to be 100% certain of breeding but, as i say, my money is on an irish bred GSW.

 

[Pariah]

Breffni,

While someone may be releasing autumn juvs in ireland, i think it is very unlikely that anyone would be releasing birds only six weeks out of the nest in july.

I think there are one or two people wondering if birds were released LAST year or the year before that have NOW produced these juveniles. Not releasing juveniles themselves...though that in itself is not beyond the realms of impossibility.

Owen

 

[KnockerNorton]

So all juv birds have left parents nad are living independently four weeks after fledging? any data to support that?

BWP.

Is there any evidence ever of a recently fledged juv travelling over 100 km of open sea? Surely this would be a very poor adaptation and juvs with a tendancy for such long dispersal over sea would be much less likely to survive than more conservative birds.

as i said, only 17 pulli have been ringed and recovered. They may be less likely to survive, but they may not. Nobody has quantified it so your argument is no better than mine. And we do know that some juvs of lots of species make big post-fledging movements, such at Nuthatch (see Matthysen)

Not enough data for statistics with only 17 records. Do you have a source for the ringing report - i can't find anything...

Migration Atlas.

why is 20 miles over land too far and at least 100 km over sea not too far?

I said it was probably too far for both obs of juvs to be considered 'linked'. 5km would be a very funny coincidence (though still not inpossible), but 20 miles is a long way.

While someone may be releasing autumn juvs in ireland, i think it is very unlikely that anyone would be releasing birds only six weeks out of the nest in july.

Nobody is suggesting that. What I was implying is that the breeding records could be from birds released in winter, whereas these 2 juvs could be natural vagrants. Or they could all be natural vagrants.

Unlike Britain, there are relatively few birders in ireland and the general population are unfamiliar with the call or knocking of peckers. If a couple of pairs were breeding somewhere in the very extensive wicklow forests they could easily go unnoticed until one turned up at a bird feeder...

GSW drum loudly, and it is audible over 500 m. They are also extremely noisy, making a terrible racket around spring, and the young make an enormous amoung of noise in the week before fledging. They call almost continuously, and loudly, and you cannot fail to notice it if anyone passes nearby (but I accept that perhaps nobody would be doing that). It is very very distinctive, however, and very very noticeable.

Its important to keep an open mind and without a nest it is impossible to be 100% certain of breeding but, as i say, my money is on an irish bred GSW.

well fair enough, you are free to think what you want. But you are making a leap of logic, putting 2 and 2 together and possibly making 5. And there is no value to be attached to your opinion (or mine - although I've not expressed an opinion about where I think they've come from, just explored the options). The facts stand alone - 2 birds 20 miles apart in late July, just after British birds have dispersed, and no inference should be taken from those facts imo, otherwise we end up with a story rather than documentation. And stories corrupt the facts by filling in the gaps in knowledge with a made-up narrative. We should accept and acknowledge the gaps in knowledge - i.e. we don't know where they came from and supposition is pointless and meaningless and could be damaging (by introducing false data - "possible/probable/definite breeding in Brittas 2008" when there is nothing solid to back it up, and other possibilities that are just as strong/stronger)

 

[HH75]

Hi all,
An interesting debate! I agree that, for now at least, nothing can be assumed based on sightings of juveniles: we have no way of knowing the provenance of the recent birds. However, it must be acknowledged that, even if breeding has yet to take place, there has been a marked change in the occurrence pattern and frequency of GSW in the last few years in Ireland. Prior to around 2002, the species was found only about once every 5-6 years, usually involving 1-2 birds per annum max even in those years where there were records (with a few notable exceptions, such as during the occasional invasion of presumed Scandinavian birds), and tended only to occur from November to March, by and large. In recent years, however, there have been many records of juveniles, between July and September, and, in this year alone, there have been records from far-flung sites such as Great Saltee, Cape Clear, Co. Galway and so on, in addition to birds in suitable breeding habitat (again, I concede that this proves nothing in and of itself) at a few sites this spring (per BINS and Irishbirding).
I personally feel that the spread of records probably points away from birds having been illegally introduced: sure, the juvs around now on the east coast could come from an indigenous introduced population alone, with no immigration whatsoever, but, were this the case, it would be distinctly unusual for there to have been spring records from Cape Clear and Great Saltee, and also for there to have been a record as far west as Galway: one would surely imagine that any Irish-bred GSW, on reaching SW Ireland, would be extremely reluctant to leave Baltimore to fly over the sea to relatively barren Cape Clear, whereas a genuine immigrant, in need of somewhere to make landfall, could be expected to be more likely to 'make do' with the cover there?
It is my own belief (and again I stress that, in the absence of ringing recoveries, this is only a theory) that the recent dramatic increase of GSW in Britain, especially that in areas just across the Irish Sea, has led to a marked increase in immigrants from that population (perhaps the increase also means that some areas are already at carrying capacity for GSW, leading to an increased likelihood of birds dispersing across the sea in the search for their own territories?), and, if they haven't done so already, it is likely that a breeding attempt will be made before too long. Given the general lack of interest and/or knowledge of the natural world shown by many Irish people (though this situation is improving slightly), it is quite likely that pair(s) would only be detected in a given area if birders stumbled across them, or, at a push, if one or more visited a garden feeder (how many Irish people would know GSW's flight call, for example? Not many, I suspect, other than actual birders. Drumming, on the other hand, may at least gain people's attention).
Owen: I assume that the information on Irishbirding, referring to the Bray woodpecker having been present since last November, is erroneous...think there are still a few teething problems with that website, leading to birds being listed as first present well before they were found. After all, the current bird there is a juvenile, and wouldn't even have been any more than a twinkle in some woodpecker's eye last November...

 

[KnockerNorton]

It is my own belief (and again I stress that, in the absence of ringing recoveries, this is only a theory) that the recent dramatic increase of GSW in Britain, especially that in areas just across the Irish Sea, has led to a marked increase in immigrants from that population (perhaps the increase also means that some areas are already at carrying capacity for GSW, leading to an increased likelihood of birds dispersing across the sea in the search for their own territories?),

Hard to disagree - just look at the population curve in Britain in recent years: http://www.bto.org/birdtrends2006/wcrgrswo.htm

 

[breffni]

Se we're all agreed that, given the number and pattern of GSW occurences in Ireland, breeding is likely sooner or later (if it has not already occured).

But out of interest, how would we rate the Brittas bird?
- no evidence of breeding
- possible breeding
- probable breeding
- confirmed breeding

(in the knowledge that the people who decide these things will take no account of our opinions)...

 

[DEREK CHARLES]

Hello Breffni,
Confirmed breeding.
There is no evidence of juvenile GSWoodpeckers migrateing or dispersing from UK breeding sites over the Irish Sea during July. Surely that is more unlikely than a pair or pairs breeding near Dublin?

Derek

 

[liverpool_bob]

Hello Breffni,
Confirmed breeding.
There is no evidence of juvenile GSWoodpeckers migrateing or dispersing from UK breeding sites over the Irish Sea during July. Surely that is more unlikely than a pair or pairs breeding near Dublin?

In other words 'probable' not 'confirmed'.

 

[DEREK CHARLES]

In other words 'probable' not 'confirmed'.

Hello Bob,
Technically you are right but i think there is no doubt that GSWoodpeckers are breeding in Ireland but it will take someone to find a nest hole and then watch a fledged juvenile fly out of it to convince everyone. Even then there will be doubters!

All the best

Derek

 

[pianoman]

:-OWhat is it about Woodpeckers that divides people into believers and unbelievers :-O

 

[HH75]

:-OWhat is it about Woodpeckers that divides people into believers and unbelievers :-O

At least we can all agree that there actually are some Great Spotteds in Ireland, regardless of whether they have bred or not, or where they came from...

 

[KnockerNorton]

Se we're all agreed that, given the number and pattern of GSW occurences in Ireland, breeding is likely sooner or later (if it has not already occured).

But out of interest, how would we rate the Brittas bird?
- no evidence of breeding
- possible breeding
- probable breeding
- confirmed breeding

(in the knowledge that the people who decide these things will take no account of our opinions)...

I'm moderately well-informed that breeding has occurred.

I'd class the Brittas birds as somewhere between no evidence and possible. It really is impossible to tell.

 

[KnockerNorton]

Hello Breffni,
Confirmed breeding.
There is no evidence of juvenile GSWoodpeckers migrateing or dispersing from UK breeding sites over the Irish Sea during July. Surely that is more unlikely than a pair or pairs breeding near Dublin?

Derek

and how much precedence is there for the current britsh breeding population, and associated dispersal?

More things to consider than here than just the annual reports. We've never been in this situation before.

 

[KnockerNorton]

Hello Bob,
Technically you are right but i think there is no doubt that GSWoodpeckers are breeding in Ireland but it will take someone to find a nest hole and then watch a fledged juvenile fly out of it to convince everyone. Even then there will be doubters!

All the best

Derek

No, that's all it will take, and that's all it should take. No more, no less. It's not a competition, or an exercise in wishful thinking. Let hsitory be recorded in cool hard facts, not opinion. In every other circumstance, we require conclusive evidence before admitting a record. A juv after post-juv dispersal is not conclusive (even if it is Irish - we can neevr know), a nest with young is. That's what all 'authorities' adhere too. But people are free to make up their personal lists and reords if they want. I's just that BirdLife or anyone else wont recognise it.

Incidently, used GSW holes are easy to spot. Why not keep an eye out?

 

[Sancho]

Incidently, used GSW holes are easy to spot. Why not keep an eye out?

That's what I don't understand. There are reports of juveniles, and rumours of breeding. I acknowledge that there are probably folk who know more but are remaining shtum to protect the birds. But, despite the comparatively low (human) population density here, and sparsity of birders, why aren't there more reports of drumming in Spring, or sightings of pairs? And why is it only juveniles we're hearing of at feeders recently...where are the adults? Don't adults frequent feeders too in the U.K.? It's all terribly exciting and interesting. But I'm still a Woodpecker Agnostic.

 

[breffni]

In every other circumstance, we require conclusive evidence before admitting a record.

Breeding records have four categories as above - only one "confirmed breeding" is conclusive. This is to reflect the fact that it can be very difficult to determine breeding for sure.

But this is not a rare breeding bird committee and this forum is replete with threads discussing possible explanations for bird sightings, behavior etc. So adopting the methodology of a rarity committee, the first question would be: Do we have a plausable story for how the bird got there. The Britas bird woudl not only have to have flown 100 km over open water, it would then have to have either flown over or around Dublin, a conurbation of 1.5 million people. If our intrepid bird flew came in from the north (at say howth), it would then have a 40 km trip through suburbia or if further inland, would go through several areas of alternative suitable habitat. If it came in from the south, eg at Bray, it would again have to cross both suitable woodland areas, suburban areas to the north or an elevation of about 500 metres with open heather to the south. Maybe I'm missing something?

 

[KnockerNorton]

Breeding records have four categories as above - only one "confirmed breeding" is conclusive. This is to reflect the fact that it can be very difficult to determine breeding for sure.

indeed, so if we're talking about proof then we need a conclusive breeding record. Otherwis eit isn't really proof of anything.

the first question would be: Do we have a plausable story for how the bird got there.

again, it's entirely up to you what "story" you make up, but it remains a story and not a fact.

The Britas bird woudl not only have to have flown 100 km over open water,

which is no problem for GSW - 3 or 400 km of open water crossings are known (eg North Sea).

it would then have to have either flown over or around Dublin, a conurbation of 1.5 million people. If our intrepid bird flew came in from the north (at say howth), it would then have a 40 km trip through suburbia or if further inland, would go through several areas of alternative suitable habitat.

Do you have much experience of the species in England? They are a suburban bird. They breen in London (a conurbation of about 10 million people), they occur regularly at barren coastal watchpoints, they breed in intensive arable with just scattered hedgerow trees. They are common at bird tables in towns and cities. Dublin is no barrier whatsoever, and is not hostile habitat.

Maybe I'm missing something?

I think you must be - GSW is not a weak-flying bird that is restricted to high forest. It has pretty much the same capabilities as a blackbird and the same habitat restrictions as a Grey Squirrel.

 

[KnockerNorton]

double post