This part of an interesting discussion that was generated following a report in Britain to shoot magpies as they are threat to other songbirds…
Monday 28th February 2005, I wasn't much impressed by the spokesman for this proposal on Radio 4 this morning. I think what is worrying is that the "It's the Magpies/Sparrowhawks what done it, Guv" school of ecology only serves to obscure the fact that this is a complex issue which involves our own use/abuse of the environment. Given that these shootin' folks & their sympathisers tend to enjoy a dominant role in the countryside, I find this worrying. If I was cynical I'd find it sinister. What was obvious, I thought in today's interview was that the RSPB spokesman (Andre Farrar I think) was willing to accept that song bird decline was complex whilst his interlocutor seemed fixated by a single cause,John
Jane Turner Sunday 27th February 2005,
You all know my views on this type of hogwash. I'm about to step on an aeroplane or I'd post the plethora of peer reviewed articles in respected journals showing that Magpies/Sparrowhaks etc have no effect what so ever on the numbers of breeding pairs of songbirds.
If they insist on using over-simplistic simplistic measure of "eats the eggs and young of smaller species" they would do better to shoot Jays. However both would be entirely futile and they'd do better to campaign for more songbird friendly farming methods.
Gaz Shilton Well said Jane. Reminds of a conversation I overheard once between a man who had just given a talk about birds of prey at our local birdclub and a woman who thought that sparrowhawks should be shot because they took HER birds were being taken from her garden. She wouldn't listen when he mentioned the Tawny Owl does similar things because to her they were too Cute to do such things. And her attitude towards him when he mentioned her cat was taking more birds than their natural predators do, well I couldn't believe it!!!
Touty
Sunday 27th February 2005, 15:35
You all know my views on this type of hogwash. I'm about to step on an aeroplane or I'd post the plethora of peer reviewed articles in respected journals showing that Magpies/Sparrowhaks etc have no effect what so ever on the numbers of breeding pairs of songbirds.
Please don't muddy the waters by bracketing specialist predators / protected species (Sparrowhawks) with generalist-switching predators / unprotected ones (Magpies).
As regards the "plethora of peer reviewed articles in respected journals" I'm genuinely interested in them, so if you could post them when you get back. I'm very interested in the methodologies they use to demonstrate that generalist / switching predators have no effect (on songbird numbers) without removing them from the equation. Safe journey.
Touty
I read Thomson, Green, Gregory and Baillie's paper when it came out. I'll read it again, now that I'm wiser and older.
Here's a paper,peer-reviewed and published in Conservation Biology that takes a less rosy (and in my opinion) more balanced view of the arguments.
http://www.uea.ac.uk/~b102/pdfs/Cote&Sutherland_1997_cb.pdf
Jane Turner
Sunday 27th February 2005,
Here are some more
No evidence of any long-term effect on songbird populations in England including in urban areas (Wilkinson 1988, British Birds, 81,657-8; Gooch et al. 1991, Journal of Applied Ecology, 68, 1068-86), and in Berlin and Osnabrück (
Jane Turner
I can see we are about to revisit the debate about post breeding numbers, which clearly predators do affect, and number of breeding birds the following spring, which evidence suggests there is no effect on! Lack of food in winter being the most likely limiting factor.
Touty Sunday 27th February 2005,
Thank you. I read Thomson, Green, Gregory and Baillie's paper when it came out. I'll read it again, now that I'm wiser and older.
Here's a paper, peer-reviewed and published in Conservation Biology that takes a less rosy (and in my opinion) more balanced view of the arguments.
http://www.uea.ac.uk/~b102/pdfs/Cote&Sutherland_1997_cb.pdf
# Tapper, SC, Potts, GR, Brockless, M (1996) The effects of an experimental reduction in predation pressure on the breeding success and population density of grey partridges (Perdix perdix). Journal of Applied Ecology, 33, 965-78
showed that (legal) predator control on Salisbury Plain for 3 years in one area (A) led to higher breeding success and spring pair density while in the area where predators were not controlled (B) breeding success and spring pair density declined. After 3 years the researchers switched the control from area A to area B and the breeding success and spring pair density in area A fell back to its original level whilst rising several-fold in area B. I grant you that grey partridges are not songbirds
Touty
Sunday 27th February 2005,
Forgot to say that the Loddington Study (completed in 2004) follows a similar if not identical methodology (actually removing predators and then letting them return, rather than area A and area B)
alcedo.atthisSunday 27th February 2005,
Jane, I do not expect a response at the moment, as you may be elsewhere, but your comment :- "Lack of food in winter being the most likely limiting factor." How does this relate then to the tonnes of food put out by bird-lovers on a daily basis especially during the winter, and even during the rest of the year. Are we as bird lovers creating an unhealthy situation of keeping the numbers high just to serve our consciences in doing our bit for the part of nature which we happen to like. Should we stop putting out this vast amount of resources, which is artificially keeping numbers well over the natural balance, and let nature take it's own course?Regards
This a study by Anil Kumar (Department of Zoology and Environmental Science, Gurukul Kangri University, Haridwar) and Dinesh Bhatt (Desert Regional Station, Zoological Survey of India, Jodhpur) on Oriental magpie robin found in the net I thought was interesting, it is about research done on different calls of this bird. This the preface para of the paper...
Birds use a variety of vocal signals while communicating. These signals play an important role in their social life. A number of avian species often deliver either calls or songs or both in a variety of contexts. Information in a call usually relates to the immediate circumstances of the caller. This study characterizes different types of calls 
on the basis of their physical characteristics and socio-biological functions, in a tropical avian species Copsychus saularis (Oriental Magpie Robin). This species has been found to use mainly six types of calls, namely territorial calls, emergence and roosting calls, threat calls, submissive calls, begging calls and distress calls in their communication. In addition, members of this species have been observed to use escape call, anger call, etc. occasionally.
Vocal signals in birds can be classified into songs and calls. A number of avian species often deliver either calls or songs or both in a variety of contexts. In general, songs are longer than calls. The former represent complex vocalizations produced by males in the breeding season. The latter are short, simple and less spontaneous. The calls are contextual and often produced with reference to a particular function1. However, there are many examples of overlaps between simple songs and calls. The study of communication not only enriches our knowledge about behavior associated with signals, but also allows us to work out the evolutionary history of any species or relationships between closely related species.
