UK Hawfinch occurence last weekend....? (1 Viewer)

[dantheman]

Are they ''U'' Turning at Lands End or going on to colonise the New World?

What is the predominant compass point (if any) in Cornwall on their departure?

Don't think any have been seen to leave yet ...

Most records seem to be between Cot Valley/Pendeen area, vismig over Falmouth and nearby Devoran, with odd scattered elsewhere.

 

[Simon Wates]

Don't think any have been seen to leave yet ...

We are getting Hawfinch passage down here in southwest Portugal - a few tens at the moment through the wider Sagres area. Probably not coming via the UK but it seems probable that they have come a very long way, the same as the UK birds. We do have breeding birds here, not so many but the birds these days at migration watches are definitely travelling. Most years we hardly get any of these, usually small single figures.. Also there are higher than normal numbers of Bullfinches and a few Brambling. Siskins are in force this autumn - but then we do get big years for those quite often.

 

[dcweather]

Are any actually stopping over? Virtually all the reports are "flew over".

 

[KenM]

Are any actually stopping over? Virtually all the reports are "flew over".

I had two yesterday, briefly in the canopy of a Hornbeam that had shed it's leaves at the top before flying off. At the moment the trees are virtually still in full leaf....bit like looking for a needle in the proverbial. :-C

 

[Dave Ball]

There seem to be a few hanging around the RSPB HQ ("The Lodge") and surrounding woodland at Sandy in Bedfordshire, though this may be more an artefact of a concentration of birders in the area rather than a concentration of Hawfinches.

 

[Captain_of_Crunch]

All the Hawfinches I have heard in Britain this autumn have been giving what I call the 'visp'-type call and which isn't described in the Collins Bird Guide. Good recording here:

http://www.xeno-canto.org/390062

The call is quite loud and is given by perched and flying birds. A good way to locate birds perched in leaf covered canopy.

 

[Xenospiza]

All the Hawfinches I have heard in Britain this autumn have been giving what I call the 'visp'-type call and which isn't described in the Collins Bird Guide. Good recording here:

http://www.xeno-canto.org/390062

The call is quite loud and is given by perched and flying birds. A good way to locate birds perched in leaf covered canopy.

Yes, that's the typical call of migrating Hawfinches. I find >90% by this call, which I only learnt about when I started "vismigging".

 

[Simon Wates]

I've heard the "visp" call type (ie; very similar or identical) in the late breeding season here (late June I think). Birds were in trees and included adults and imms., not fledglings. They were calling plenty and the "tic" calls were mixed in too.

 

[KenM]

Did Greater London peak yesterday with 50 plus (doubling the previous day's figure) reported (including a flock of 26+ in Surrey!)...with just the one report so far today...as per London Wiki Birds, or will it peak and trough into the Winter months, as their are still plenty of sightings in the shires today?

 

[halftwo]

Been thinking about this a bit more:

Maple seeds contain saponins (toxic)
Yew seeds contain taxine (toxic)
Hornbeam and Beech seeds contain tannins (toxic)

So do many other tree seeds contain various toxins.

But if a Hawfinch eats a small amount of each of lots of different seeds, then it has a far better chance of avoiding a damaging dose of any one toxin. Some of the toxins may even have neutralising effects on other toxins (e.g. saponins and tannins are good at binding to other organic compounds, which is why they're toxic in the first place).

That could explain well why Hawfinches do best where tree species diversity is greatest, and also why they are such "notoriously fussy eaters".

An interesting research project for a PhD student, perhaps?

Thinking about this - doesn't explain how a Mistle Thrush can eat yew almost exclusively without any harm coming to it. Some (most?) birds seem immune.

 

[Nutcracker]

Thinking about this - doesn't explain how a Mistle Thrush can eat yew almost exclusively without any harm coming to it. Some (most?) birds seem immune.

Mistle Thrushes eat the non-toxic red aril (cone scale, to be precise); they swallow the toxic seed whole and pass it out in the droppings undamaged, with the toxins not released.

Hawfinches crack the seed open and eat the kernel. Even just 10 seeds is enough to kill a child, so Hawfinches much have some immunity to the toxins, but varying the diet will still help by reducing the dosage of any one toxin.

For a similar comparison, we eat cherries, but we don't eat the cherry stone kernel (also toxic, with cyanogenic glycosides). Hawfinches crack the seed open and eat the kernel.

 

[Jos Stratford]

Even just 10 seeds is enough to kill a child, so Hawfinches much have some immunity to the toxins, but varying the diet will still help by reducing the dosage of any one toxin.

Still not sure of this, as said Hawfinch is abundant in LT where tree diversity is lower, ie possibly against the idea that Hawfinches do best where tree species diversity is greatest, but moreover I wonder if the variable diet necessarily applies in reducing dosage that a bird might expose itself at any one time - in my experience, the variability is perhaps more usually seasonal/period variability of diet, rather than at a particular time. What I try to say here is that Hawfinch often seem to linger at available food sources, feeding near non-stop on these while that food is easily available, then moving onto another when this becomes exhausted or others become available. If this does reflect reality, then short time dosage should actually be extremely high. Perhaps long-term dosage reduced though. Anyhow, conclusion, all Hawfinches are actually dead

 

[Jos Stratford]

Anybody in an area of the UK where they are appearing though might do well to scatter large quantities of sunflower seeds in their gardens, they are extremely fond of these.

 

[halftwo]

Mistle Thrushes eat the non-toxic red aril (cone scale, to be precise); they swallow the toxic seed whole and pass it out in the droppings undamaged, with the toxins not released.

Hawfinches crack the seed open and eat the kernel. Even just 10 seeds is enough to kill a child, so Hawfinches much have some immunity to the toxins, but varying the diet will still help by reducing the dosage of any one toxin.

For a similar comparison, we eat cherries, but we don't eat the cherry stone kernel (also toxic, with cyanogenic glycosides). Hawfinches crack the seed open and eat the kernel.

Interesting stuff - I'm impressed with your knowledge of all things arboreal, N. Is this something you studied/study - or part of your wider interest in natural history?

 

[Adey Baker]

Still not sure of this, as said Hawfinch is abundant in LT where tree diversity is lower, ie possibly against the idea that Hawfinches do best where tree species diversity is greatest, but moreover I wonder if the variable diet necessarily applies in reducing dosage that a bird might expose itself at any one time - in my experience, the variability is perhaps more usually seasonal/period variability of diet, rather than at a particular time. What I try to say here is that Hawfinch often seem to linger at available food sources, feeding near non-stop on these while that food is easily available, then moving onto another when this becomes exhausted or others become available. If this does reflect reality, then short time dosage should actually be extremely high. Perhaps long-term dosage reduced though. Anyhow, conclusion, all Hawfinches are actually dead

In the 'NN' book 'Finches' Ian Newton comments that they return daily to the same place if food holds out and late in the winter they return to woodland to eat buds of oak and other trees and the terminal shoots of yew.

He doesn't list the full range of food taken though, so there's no mention of the fruits of yew either way.

 

[Jos Stratford]

In the 'NN' book 'Finches' Ian Newton comments that they return daily to the same place if food holds out and late in the winter they return to woodland to eat buds of oak and other trees and the terminal shoots of yew.

Interesting, thanks. Pretty much reflects my observations.

 

[Torchepot]

When we first had hawfinches visiting our feeding station I thought I'd give them a treat and saved the stones from some cherries, after drying them for a couple of weeks I put them out next to the sunflower seeds and they were totally ignored! It's been suggested to me that they may prefer last year's crop - but I haven't tried storing them over winter yet. I do wonder if toxins would be as potent in older seeds?

I'ts curious that they have the reputation of fussy eaters - is this because they don't visit bird feeders? Here they never feed from the hanging feeders unless they have a tray under them catching the bits (they perch on the tray) - they much prefer the big table or the ground.

 

[King Edward]

Mistle Thrushes eat the non-toxic red aril (cone scale, to be precise); they swallow the toxic seed whole and pass it out in the droppings undamaged, with the toxins not released.

Great Tits are very keen on eating Yew seeds, hammering them open like a Nuthatch. I hear them doing this quite a lot.

 

[Nutcracker]

When we first had hawfinches visiting our feeding station I thought I'd give them a treat and saved the stones from some cherries, after drying them for a couple of weeks I put them out next to the sunflower seeds and they were totally ignored! It's been suggested to me that they may prefer last year's crop - but I haven't tried storing them over winter yet. I do wonder if toxins would be as potent in older seeds?

Because sunflower seeds are easier to eat, would be my guess - less energy needed to crack them, toxin-free kernels, and oil-rich too. Once you've got them used to coming, try a day when they only have cherry stones as an option, and see what happens then.

I'd be very doubtful they'd prefer older stale seeds to fresh ones. Maybe they were already too old? They mainly go for cherry seeds in summer, when the new crop is ripe (cherry growers don't like them, because they'll rip up the fruit to take the stones still on the tree).

 

[KenM]

Many of the seeds that Hawfinches regularly take e.g. Yew, Mistletoe, Laburnum and a myriad of other seeded fruit species are given as poisonous, and as such are given a wide berth by humans. However the occurence of any real ill effects are often occasional, and only in extreme cases are there any serious side effects. That said...when I first moved into my present abode (34years ago) I had the good fortune one early July morning, to observe a movement in my Hawthorn hedge. After much waiting, I eventually noticed a single eye staring at me from within the hedge, rest of the bird was totally concealed, eventually the accompanying bill morphed into view...A Hawfinch I exclaimed :eek!: berries exuding over the rim of the lower mandible, along the entire length (to the point of the bill being partly open, as it was crammed with berries). I stared in almost disbelief and wonder, subsequent reference has stated that Hawthorn seeds contain cyanide (as do apple seeds), thus the toxicity level in the brown seeds of the former (even just a few) would be extremely high. Therefore I would assume that a bird that can exert c175 lbs per sq.inch+pressure to split an olive stone, would also have evolved an efficient digestive system that would enable it to cope with quantative cyanide poisoning?