earleybird
Well-known member
Has anyone considered the possibility that cats and Sparrowhawks may have evolved to working together ? :t: just kiddin ok
ditto, I agree
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Sparrowhawks responsible for House Sparrow decline says scientist (1 Viewer)
- Thread starter John B (not the sloop)
- Start date
Has anyone considered the possibility that cats and Sparrowhawks may have evolved to working together ? :t: just kiddin ok
ditto, I agree
John B (not the sloop)
Don't blame me I didn't vote for 'em
Huh? When were Sparrowhawks reintroduced and who did the reintroducing? |:S|
deboo
.............
Did I really read this? From a 'scientist'?
*blinks*
nope...didn't miss it. Oh dear...oh dear indeed.
\thread.
Thanks to Spencer, Stephen and Earleybird for the words of encouragement – and don’t worry - I know you still don’t believe me! When you decide to put yourself out there, it’s pretty much a case of taking the rough with the smooth, but it is nice to get the odd bit of positive feedback.
To understand the silence from the likes of Peach, Newton et al. you really have to get inside the mind of a professional ornithologist. To most amateur enthusiasts, it probably seems like about the best thing you could possibly do. However the truth is, once you’ve got your feet under the table, it becomes pretty much like any other job, and your priorities are simply getting through the day, paying off the mortgage, putting the kids through school, just like everybody else. All thoughts of solving the great mysteries of nature soon become a distant memory.
Against this background the ‘professional’ mentality takes over. You want to hear Peach’s opinion? Put your hand in your pocket. You want to catch the pearls of wisdom dripping from the lips of Newton? Insert your debit card here.
Their calculation is that they don’t have to engage in this debate, either on birdforum or anywhere else, since it will gradually fade away, leaving their preferred interpretation of events intact. They will only emerge from their bunker if failure to do so begins to tarnish their reputations, and thereby threaten their ability to make money in the business.
http://www.cpbell.co.uk
http://www.youtube.com/CultoftheAmateur
To understand the silence from the likes of Peach, Newton et al. you really have to get inside the mind of a professional ornithologist. To most amateur enthusiasts, it probably seems like about the best thing you could possibly do. However the truth is, once you’ve got your feet under the table, it becomes pretty much like any other job, and your priorities are simply getting through the day, paying off the mortgage, putting the kids through school, just like everybody else. All thoughts of solving the great mysteries of nature soon become a distant memory.
Against this background the ‘professional’ mentality takes over. You want to hear Peach’s opinion? Put your hand in your pocket. You want to catch the pearls of wisdom dripping from the lips of Newton? Insert your debit card here.
Their calculation is that they don’t have to engage in this debate, either on birdforum or anywhere else, since it will gradually fade away, leaving their preferred interpretation of events intact. They will only emerge from their bunker if failure to do so begins to tarnish their reputations, and thereby threaten their ability to make money in the business.
http://www.cpbell.co.uk
http://www.youtube.com/CultoftheAmateur
Interesting,
I drew alot of inspiration from a website called 'Sparrows Need Hedges' written by Mr Donald E Lyven, its been around for some years. However when I recently tried to return to the site I found it was no longer there, there were some interesting letters from Summersmith on it. I Later discovered that Mr Lyven had become a serious green party candidate for Barnett that same year. Mr Lyven is himself a member of bird forum, I wondered if this was merely a coincidence or the reason for the sites disapearance was a political one, I hope not for he seemed to be a genuine chap in touch with his environment.
I drew alot of inspiration from a website called 'Sparrows Need Hedges' written by Mr Donald E Lyven, its been around for some years. However when I recently tried to return to the site I found it was no longer there, there were some interesting letters from Summersmith on it. I Later discovered that Mr Lyven had become a serious green party candidate for Barnett that same year. Mr Lyven is himself a member of bird forum, I wondered if this was merely a coincidence or the reason for the sites disapearance was a political one, I hope not for he seemed to be a genuine chap in touch with his environment.
birdbrainer
but some people call me Helen!!
Wow this thread takes some trawling through! All I can add is that we have had a healthy population of house sparrows in our hedgerow at the back of our garden. I have seen a sparrow hawk take one once in 20 years. They come to my feeders and bird table and feed on the ground. A regular all rounder.
We have three cats which ignore the birds preferring the occasional vole or mouse. :cat:
We have three cats which ignore the birds preferring the occasional vole or mouse. :cat:
GiG
Well-known member
Have been following this thread for a while and thought it was about time I added my thoughts especially after a phone call I had the other day (see later).
While I do endorse scientific study to help solve problems/ask questions there is a lot of info provided from BF members on here to put forward that the sparrowhawk is not the sole factor in house sparrow decline. Remember how much of the birding information such as occurences and populations is down to everyday birding enthusiasts, such as the BTO Atlas currently running along with other BTO surveys, and each year all the county bird reports are compiled by an army of volunteers.
From my own observations, there is a regular house sparrow population that visit my garden. They breed along our road. Firstly, the population has been slightly increasing each year. I regularly see sparrowhawk from/in the garden as a pair breed in a park close by. I've never seen them take a house sparrow - only blackbird, blue tit, starling and woodpigeon.
What I have noticed this year though is that the sparrows are not in their normal roost site, they would regularly use a tall thick jumble of forsythia with hop growing over it as a place to roost, fly from it to the feeders further up the garden. The feeders are up in a hawthorn tree as there are numerous cats in the vicinty. The next door neighbour moved out and the landlord came in and cut the forsythia back on their side so it is still tall, 15 ft, but is less dense now. As a consequence they will use it to fly to the feeders but less regularly so and do not roost there now. They are more inclined to fly from the privet on the other side of my garden, in fact definitely more so, as I can often see a number of them with their heads poking out. Fortunately they roost a few gardens down now.
Having done the BTO Atlas the last few years it is noticeable that the house sparrows that I've recorded were almost always where human habitation was within the farmland areas. But a couple of years ago I did a tetrad in the town I live and there was a distinct area where I recorded house sparrows. Following the route round the area that was more suburban with tended gardens I noted very few house sparrows compared to the area which was a poorer council estate, where the garden were less tended and the house sparrows had nesting sites. In fact looking at my notes for example on the second breeding visit, two were seen in the suburban section with no breeding, whereas in the estate section 21 were counted with nest with young.
As I mentioned at the start about a phone call; I rang my parents at xmas and as often we do, talk about birds in the garden - I got my first ever waxwing in the garden on xmas day! My parents who are just general bird lovers who like to watch the birds in their garden and put a lot of food out. My mother said that there were a lot less house sparrows in the garden this winter and she said it was due to their next door neighbour cutting a thick hawthorn hedge down at the bottom of her garden. My parents had noted that this was where the sparrows would congregate before flying to their feeders and were sure that this was the cause of the decline. They regularly get sparrowhawk in the garden, which they were not keen on at first, until I pointed out they they had a good population of different species in the garden which had not disappeared, in fact house sparrow and goldfinch had been increasing. They have noted that greenfinch is very rare in the garden now, but that is probably down to that disease, trichomonosis.
What I was trying to show from the notes above is that it is evident that many factors should be taken in to account to determine a decline in house sparrows and not solely on the sparrowhawk.
Gi
While I do endorse scientific study to help solve problems/ask questions there is a lot of info provided from BF members on here to put forward that the sparrowhawk is not the sole factor in house sparrow decline. Remember how much of the birding information such as occurences and populations is down to everyday birding enthusiasts, such as the BTO Atlas currently running along with other BTO surveys, and each year all the county bird reports are compiled by an army of volunteers.
From my own observations, there is a regular house sparrow population that visit my garden. They breed along our road. Firstly, the population has been slightly increasing each year. I regularly see sparrowhawk from/in the garden as a pair breed in a park close by. I've never seen them take a house sparrow - only blackbird, blue tit, starling and woodpigeon.
What I have noticed this year though is that the sparrows are not in their normal roost site, they would regularly use a tall thick jumble of forsythia with hop growing over it as a place to roost, fly from it to the feeders further up the garden. The feeders are up in a hawthorn tree as there are numerous cats in the vicinty. The next door neighbour moved out and the landlord came in and cut the forsythia back on their side so it is still tall, 15 ft, but is less dense now. As a consequence they will use it to fly to the feeders but less regularly so and do not roost there now. They are more inclined to fly from the privet on the other side of my garden, in fact definitely more so, as I can often see a number of them with their heads poking out. Fortunately they roost a few gardens down now.
Having done the BTO Atlas the last few years it is noticeable that the house sparrows that I've recorded were almost always where human habitation was within the farmland areas. But a couple of years ago I did a tetrad in the town I live and there was a distinct area where I recorded house sparrows. Following the route round the area that was more suburban with tended gardens I noted very few house sparrows compared to the area which was a poorer council estate, where the garden were less tended and the house sparrows had nesting sites. In fact looking at my notes for example on the second breeding visit, two were seen in the suburban section with no breeding, whereas in the estate section 21 were counted with nest with young.
As I mentioned at the start about a phone call; I rang my parents at xmas and as often we do, talk about birds in the garden - I got my first ever waxwing in the garden on xmas day! My parents who are just general bird lovers who like to watch the birds in their garden and put a lot of food out. My mother said that there were a lot less house sparrows in the garden this winter and she said it was due to their next door neighbour cutting a thick hawthorn hedge down at the bottom of her garden. My parents had noted that this was where the sparrows would congregate before flying to their feeders and were sure that this was the cause of the decline. They regularly get sparrowhawk in the garden, which they were not keen on at first, until I pointed out they they had a good population of different species in the garden which had not disappeared, in fact house sparrow and goldfinch had been increasing. They have noted that greenfinch is very rare in the garden now, but that is probably down to that disease, trichomonosis.
What I was trying to show from the notes above is that it is evident that many factors should be taken in to account to determine a decline in house sparrows and not solely on the sparrowhawk.
Gi
earleybird
Well-known member
this co-incides exactly with the situation in my garden and that of my neighbours in our 4x cottage terrace.
The end of terrace garden has a 7 foot high stone garden wall built against the rear wall of an adjacent 2x storey building. 12 years ago when I moved in, all of the neigbourhood sparrows would congreate at various times of the day in the dense foliage growing along the top of the garden wall . From this safe vantage point they would fly down into the feeders in the 4x cottage gardens .I estimated their number approx 45+ birds, sometimes more and the noise was deafening :eek!:
About six years ago the end cottage was sold and refurbished and part of the work was to remove the ivy and elder and other foilage running along the garden wall in order to build a rear extension.
Since this time house sparrow numbers plumeted and have never recovered. The largest number of house sparrows counted in my garden this year was 18 which was exceptional . Mostly the count is 12x or less .
Unless I had witnessed this transformation first hand I would never have credited it possible that cutting back this rough foliage on top of a garden wall could have effected Housesparrow numbers so dramatically and for such a sustained period. This discussion has motivated me to think about providing a congreation point for the smaller birds adjacent to the feeders for all year round cover as we have nesting Sparrowhawks next door which regularly take starlings and blackbirds from my garden
It would seem to me that this bears out your observation that it is perhaps the loss of foliage adjacent to the House sparrow feeding areas (where they congreate prior to feeding )that is the significant factor in the decline of Housesparrows and not necessarily the loss of their nesting/ roosting habitat
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All this confirms that a very specific habbitat structure has become increasingly important for sparrows. There are instances where this is not as important, in the absense of severe competition from other seed eaters, lack of predators etc, but these situations are becoming rare in the UK. People may believe that their area is devoid of greenary yet there are plenty of sparrows, yet there may be one seemingly insignificant bush of the correct density that is probarbly vital to that colonies success.
I provide a range of food all through the year, but sparrows only appear during the breeding season for live mealworms, the colonies are only about 50 metres away. This may demonstrate that they struggle to find enough invertibrates in the several gardens they have to cross before they get to mine.
I've also noticed that although there are still a good amount of privet hedges in my area they are not often utilised by sparrows. I believe this has something to do with the appearance of motorised hedge cutters over the last couple of decades. People are more inclined to cut more often with these labour saving devises. The result is a much tighter manicured hedge that may not be as suitable and I suspect more likely disturbance during the breeding season. Sparrows around here tend to use old shrubs or slightly more open beech hedges that require less trimming.
The situation is obviously not cut and dry which is why there is so much opposition to Mr Bells results. There are just too many variables that are unresolved.
I provide a range of food all through the year, but sparrows only appear during the breeding season for live mealworms, the colonies are only about 50 metres away. This may demonstrate that they struggle to find enough invertibrates in the several gardens they have to cross before they get to mine.
I've also noticed that although there are still a good amount of privet hedges in my area they are not often utilised by sparrows. I believe this has something to do with the appearance of motorised hedge cutters over the last couple of decades. People are more inclined to cut more often with these labour saving devises. The result is a much tighter manicured hedge that may not be as suitable and I suspect more likely disturbance during the breeding season. Sparrows around here tend to use old shrubs or slightly more open beech hedges that require less trimming.
The situation is obviously not cut and dry which is why there is so much opposition to Mr Bells results. There are just too many variables that are unresolved.
I for one would love to see a goverment initiative that encourages people to plant natives in their garden. If everyone just planted a single Hawthorn in their garden the benefits would be imense. Hawthorn is probably the best allrounder and has been mentioned quite alot on this thread, it is the foodplant of many moths and a huge number of invertibrates second only to Oak and Willow. Hawthorn dosn't grow too tall, provides nectar and a heavy crop of berry's, provides excellent protection and can be grown as hedge or small specamin tree, wonderful.
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occasional
Well-known member
Re Spain. When I read the link on the Spanish sparrowhawk population posted by Jane in post #310, my first reaction was to look for a missing zero in the population figure. In fact there appears to be no typographical error, so I suspect this indicates that there has been a very substantial increase in the Spanish sparrowhawk population in recent years.
As to sparrowhawks in Spanish cities; about 5 years ago a friend found a sprawk trying to remove a goldfinch from a cage on her fifth floor balcony, and when she mentioned this, at least two other people recounted that they had had a similar experience.
Even on this trivial evidence I would suggest that Spanish data are unlikely to contradict CPB"s thesis.
And a question for CPB - is it possible to demonstrate from your data a clear directional basis to the house sparrow decline, ie from W to E, or perhaps towards a fixed point such as Cambridge ?
As to sparrowhawks in Spanish cities; about 5 years ago a friend found a sprawk trying to remove a goldfinch from a cage on her fifth floor balcony, and when she mentioned this, at least two other people recounted that they had had a similar experience.
Even on this trivial evidence I would suggest that Spanish data are unlikely to contradict CPB"s thesis.
And a question for CPB - is it possible to demonstrate from your data a clear directional basis to the house sparrow decline, ie from W to E, or perhaps towards a fixed point such as Cambridge ?
GiG/Earleybird/Spencer
All your observations corroborate the importance of cover for local distribution of sparrows, but I would be cautious in deducing that local declines associated with loss of cover account for a significant proportion of national decline when aggregated together, since they might just reflect spatial redistribution.
This is one of the more robust of the arguments contrary to the predation hypothesis put forward by the RSPB, who claim that the patterns we demonstrated merely show sparrows avoiding gardens where Sparrowhawks occur, so represent local redistribution. In this case the argument fails, since we show that Sparrowhawk incidence accounts for essentially all of the observed decline, from which the RSPB would be forced to conclude that no real decline has occurred. The argument remains valid in the case of the cover hypothesis, however, since no quantitative link has been established between cover and sparrow decline.
I get a sense that the constructive debate on the thread increasingly revolves around the extent to which habitat change has interacted with predation in causing sparrow decline. It’s worth remembering, therefore, that the RSPB still swears blind that there is no evidence that predation affects songbird populations. They know this is not the case, and I’m afraid they are simply lying to the public.
The short answer is not really, but there’s no reason to expect that there should be. To understand why, take a look at Figure 2 in the paper (downloadable here). Figure 2c indicates that sparrows start declining in zones 1-3 (the three westernmost zones) from the mid-1980s, but only from the early 1990s in the easternmost zone 4. The reason for this can be seen in Figure 2a, which shows the growth of sparrowhawk incidence in the four zones. In the early 1970s this is higher in the west, but it grows more rapidly further east, so that by the early 2000s the relative incidence is reversed.
If there had been a simple, progressive recolonisation at the same rate across the country, one might have expected a W-E trend in sparrow decline, but the actual situation was more complicated than this. Figure 2e shows that the trends in Sparrowhawk incidence in the four zones predict the trajectory of sparrow decline with precision.
Incidentally, the fact that there is no clear W-E trend in sparrow decline is another of the counter-arguments offered by the RSPB, but as described above this betrays a naïve and simple minded approach to the problem.
http://www.cpbell.co.uk
http://www.youtube.com/CultoftheAmateur
All your observations corroborate the importance of cover for local distribution of sparrows, but I would be cautious in deducing that local declines associated with loss of cover account for a significant proportion of national decline when aggregated together, since they might just reflect spatial redistribution.
This is one of the more robust of the arguments contrary to the predation hypothesis put forward by the RSPB, who claim that the patterns we demonstrated merely show sparrows avoiding gardens where Sparrowhawks occur, so represent local redistribution. In this case the argument fails, since we show that Sparrowhawk incidence accounts for essentially all of the observed decline, from which the RSPB would be forced to conclude that no real decline has occurred. The argument remains valid in the case of the cover hypothesis, however, since no quantitative link has been established between cover and sparrow decline.
I get a sense that the constructive debate on the thread increasingly revolves around the extent to which habitat change has interacted with predation in causing sparrow decline. It’s worth remembering, therefore, that the RSPB still swears blind that there is no evidence that predation affects songbird populations. They know this is not the case, and I’m afraid they are simply lying to the public.
The short answer is not really, but there’s no reason to expect that there should be. To understand why, take a look at Figure 2 in the paper (downloadable here). Figure 2c indicates that sparrows start declining in zones 1-3 (the three westernmost zones) from the mid-1980s, but only from the early 1990s in the easternmost zone 4. The reason for this can be seen in Figure 2a, which shows the growth of sparrowhawk incidence in the four zones. In the early 1970s this is higher in the west, but it grows more rapidly further east, so that by the early 2000s the relative incidence is reversed.
If there had been a simple, progressive recolonisation at the same rate across the country, one might have expected a W-E trend in sparrow decline, but the actual situation was more complicated than this. Figure 2e shows that the trends in Sparrowhawk incidence in the four zones predict the trajectory of sparrow decline with precision.
Incidentally, the fact that there is no clear W-E trend in sparrow decline is another of the counter-arguments offered by the RSPB, but as described above this betrays a naïve and simple minded approach to the problem.
http://www.cpbell.co.uk
http://www.youtube.com/CultoftheAmateur
I know you don't believe that habitat has degraded but if loss of cover is happening on such a large scale, where are they going to redistribute to. The same reasoning can be applied to the idea that sparrows are avoiding gardens with hawks in, if the hawks are everywhere, where can sparrows hide.
I think the argument would be that sparrows are simply avoiding feeders and foraging where there is less risk of predation, since they somehow calculate that the benefit of using feeders is outweighed by the added risk.
The temporal trend in availability of cover is clearly the issue on which we disagree here, but I doubt whether this can be resolved scientifically. This is because I don’t think that it would be possible to reconstruct any trend in cover with sufficient precision to explain sparrow population trend to a significant degree, notwithstanding some of the interesting suggestions that have been put forward on the thread such as the one concerning aerial photography by Frenchy @#257.
Instead, the urgent priority must be to apply the proven approach we used in the Auk paper to other species that have declined. Unfortunately the data required for this are controlled by the cynical current management of the British Trust for Ornithology, who appear determined to scupper any research proposals that threaten the dogmas which provide them with so much of their income and influence. The fact that they are allowed to use data generated by the hard work of volunteers as a corporate asset, while receiving £½million per year for their monitoring schemes from the taxpayer, is nothing short of a scandal. On top of all this they pretend on their new website that their data are available through the National Biodiversity Network. It’s all faintly nauseating, and shows clearly why BTO datasets need to be made genuinely open source for ornithological science in the UK to recover some of its integrity.
The BTO isn’t a public body so the Freedom of Information Act doesn’t apply. They have the luxury of being able to suck on the teat of the taxpayer with no accountability whatsoever. It’s therefore hardly surprising that they treat their datasets as a private asset to be used for the purpose of manipulating public policy to generate further income. JNCC have been trying to push them into making their datasets open source through the National Biodiversity Network, but the BTO keep giving them the finger, and ultimately JNCC are too limp-wristed to call their bluff.
Remember, the BTO is a private organisation, and it serves its own interest, not that of the public. We should therefore be more than a little concerned that more and more of our money is flowing into their coffers. Since I was last a member the BTO has at least quadrupled in size, though their membership seems to be pretty much what it was back then. The suits up at Thetford appear to have done a ruthlessly efficient job of empire building on the back of public funds.
In the same way that neither you nor I have a regulator nor are accountable to anyone.
I presume your boss wherever you work doesn’t read Birdforum, otherwise I’ll be interested to hear your explanation of how completely unaccountable you are.
The nearest thing the BTO have to a regulator would be the Charity Commission, but they are just interested in making sure they don’t turn a profit. That’s why it’s so important to keep growing. If you’re a director of an outfit that has 150 staff and a turnover of £5 million, you pay yourself the salary and benefits that the market ‘demands’, i.e. a lot more than if it has 30 staff and a £½million turnover.
They have contracts for the public funding they receive, but then who’s to say whether they deliver or not, since they’re supposedly the experts. I’ve scoured the JNCC contract for something I could use to winkle the data out of them, but to no avail. Ultimately JNCC are just another bunch of public sector jobsworths who don’t dare rock the boat.
The Romans had it right: Quis custodiet ipsos custodes? Who shall guard the guards themselves?
http://www.cpbell.co.uk
http://www.youtube.com/CultoftheAmateur
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