sparrows & declines

To: "crompton" <>, "Birding-aus (E-mail)" <>
Subject: sparrows & declines
From: "Philip Veerman" <>
Date: Sun, 26 Feb 2006 23:16:19 +1100
Hi All,
Well of course that is a big question that G.Crompton asked and there are House Sparrow populations around the world that are in decline. Not that all are consistent. There are many ideas about and most relate to opportunities for feeding and nest building. Generally if adjoining agriculture declined and people were more tidy then sparrows declined. These can clearly be very localised impacts. Having said that, findings of decline are occurring in most studies.
I was sent an advance copy of the new 450 page book Birds in European Cities Edited by John G. Kelcey and Goetz Rheinwald 2005. This book is an impressive compilation from 23 expert local authors, on the avifaunal communities of 16 European cities, in 11 countries. I actually had a small role in editing or refereeing a couple of chapters, a few years ago, when the book was in very early draft stage. There is a lot of interest developing about status patterns of urban birds. The issue of House Sparrow populations rates several mentions (along with many other species of course). This book is a research and status book also useful for travellers, not a picture book or field guide.
Few places have consistently collected surveys of continuous long-term data on bird populations, that have been published that can answer the question, but this is one. The information on the species from my book: Veerman, P. A. 2003 & 2006, Canberra Birds: A Report on the first 21 years of the Garden Bird Survey. is as follows:

"House Sparrow Passer domesticus

This is a species well known for their strong dependence on human habitation (Summers-Smith 1963). This species is more common in the urban (town centres, major shopping centres) than suburban environment. For the first 14 years it was the second most common species but it has since declined. The monthly pattern is quite regular but of small amplitude. From a November low, rises to the March peak. This is associated with breeding. Apparent numbers decline as birds are nesting, due to birds being out of sight and the fact that much nesting occurs around town centres and buildings away from garden areas. The March peak represents the impact of flocks of newly independent juveniles. Winter numbers are fairly uniform. The fact that July abundance is higher than that of June (eleven months later), is most likely due to the steady population decline of the species. The abundance has declined smoothly and markedly, particularly from Years 6 to 21. This is clearly a valid result as this is a widespread species. However, it could be a long-term undulation as the population was increasing from Years 1 to 6. Breeding records were highest in the mid 1980s and have declined since. Nest building and other activities at nest commence in mid-September but most breeding activity is from October to January. There is a large overlap with many nest activities commencing late, these are rarely followed by observations of dependent young. There are few dependent young after late February.
Graphs on page: 104, Rank: 11, Breeding Rank: 9, Breeding graph on page: 107, A = 7.07589, F = 96.11%, W = 52.0, R = 73.676%, G = 9.60."

The decline in the House Sparrow is occurring around the world, well at least in Europe, so Canberra is not an exception. I have had correspondence with various others and seen publications attesting to that. eg work of another Garden Bird Survey, done in Holland.
Interestingly I have had the following e-mail discussion (recently) with someone from the ZOOLOGICAL SOCIETY OF LONDON who wrote to me this week about the GBS trends, in particular following up about the House Sparrow and its avian predators around the world. Extracts follow:

Dear Philip
That is superb - you've certainly whetted my appetite to see the book! I've just emailed our librarian declaring it to be an essential addition to the collection, so hopefully she'll be in touch. The EGI library is in Oxford - not too far away. There's probably also a copy in the British Museum Library at Tring, as they're supposed to have "everything" on birds.
The items from the entries below that stand out for me are:
[Collared Sparrowhawk] declined to a low in Year 11 (1991) and since then has had a dramatic increase. For the first 14 years [House Sparrow] was the second most common species but it has since declined. Wherever I look, there is an almost relentless inevitability about finding increases in the local small Accipiter where House Sparrows decline, and conversely no change in status of the Accipiter where they don't. Granted your Currawongs have also increased, but I somehow can't see a generalized, opportunist predator as a more likely culprit than a specialist like the Collared Sparrowhawk - esp. as you tell us that it's probably the predator most at home in suburban environments.

Chris Bell
Conservation Programmes
Zoological Society of London
Regent's Park
London NW1 4RY


to which I have responded:
"If there is a connection between small Accipiter increase and House Sparrows decline, then I can see causative only in that direction (i.e. House Sparrows decline could hardly cause a small Accipiter increase). It is indeed an interesting connection, it makes sense, and if it helps, you are welcome to cite this study as a consistent result. I wouldn't claim it on the basis of this study alone, but then I didn't know anyone had found such a connection. I'm sure there are many other factors involved. The Collared Sparrowhawk here takes a lot of Common Mynas and Common Starlings too. There may be partitioning between the sexes as to who takes what, as the female is much bigger than the male."
Philip Veerman
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