|J.D. Summers-Smith; alle redenen achteruitgang huismus
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|Auteur:||wittemus [ April 12th, 2011, 1:54 pm ]|
|Titel:||J.D. Summers-Smith; alle redenen achteruitgang huismus|
J.D. Summers-Smith; alle redenen achteruitgang huismus
Berichtdoor witteMus » 19 jun 2010, 16:11
Denis Summers-Smith stelde vandaag (19juni2010) een aantal stukken ter beschikking voor publicatie op dit huismussenforum.nl
(Wie ze kan en wil vertalen voor niet-engels lezenden; je bent van harte welkom !)
J.D. Summers_smith via e-mail aan Stichting Witte Mus:
By all means use anything you like from me on your web site. From time to time I write what I call File Notes. These roughly fall into three groups: ready-made answers to frequently asked questions (e.g. how can one sex juveniles, what is the sex ratio); topics that for some reason have interested me and it is convenient to assemble in one place all the information on the topic (e.g. sparrows and yellow crocuses, sparrows on ships and airplanes); collections of data preparatory to writing a paper.
I am attaching a list of my File Notes. If there are any of these that you think might be of interest, please let me know and I can send you a copy. Again you might like to use the odd one as the basis for an item on your web site.
Daar maken we natuurlijk heel graag gebruik van.
Dus hier een eerste deel.
Het is een zo volledig mogelijke opsomming van argumenten die Denis heeft horen aanvoeren.
Argumenten die de afname van het aantal huismussen in stedelijk gebied zouden kunnen verklaren.
Er bij wordt verwezen naar ter zake doend onderzoek.
In schuin gedrukte tekst heeft hij zijn ideeën over dat argument erbij gezet.
JD Summers-Smith - File Note V-20; SUGGESTED CAUSES OF URBAN SPARROW DECLINE
Met vriendelijke groet,
Het huismussenForum beheer
|Auteur:||wittemus [ April 12th, 2011, 1:56 pm ]|
|Titel:||Re: J.D. Summers-Smith; alle redenen achteruitgang huismus|
re: J.D. Summers-Smith; alle redenen achteruitgang huismus
Berichtdoor witteMus » 29 jun 2010, 17:30
Omdat het toch wat makkelijker leest als de tekst gewoon voor je in beeld staat zet ik pagina voor pagina van deze File Note V-20 op het forum.
File Note V-20
SUGGESTED CAUSES OF URBAN SPARROW DECLINE
Three species of Passer that inhabit man’s urban environment have recently
undergone severe declines. This has been best documented for the House Sparrow,
Passer domesticus in the British Isles and NW Europe, where the decline appears to
have started about 1990 (Summers-Smith 2003a, 2005); but more recently similar
declines have been recorded in the Italian Sparrow P. italiae (Dinetti 2007) and the
Tree Sparrow P. montanus in Japan (Mikami 2009).
Despite considerable research, the cause/causes of these declines has/have not been
established. This File Note has been prepared to provide an easy reference to the
various suggestions that have been advanced. Note the word ‘suggestions’. These
come from a wide spectrum of sources: off-the-cuff remarks, letters and e-mails that I
have received, newspaper articles and letters, Web sites, up to and including scientific
papers in peer-reviewed journals. References are given for the source of the various
suggestions. As a full explanation still eludes us, I think it sensible not to ignore any
idea, however wild.
In most cases, these suggested causes are at best described as ‘perceived associations’,
even when statistically correlated, rather than causal relationships. They are divided
into the following Sections that are listed in alphabetical order to avoid any indication
of importance. The allocations to specific sections are arbitrary, rather than
fundamental. This is a matter of convenience as many of the ideas are inextricably
intertwined. Cross-references are used where the suggestion clearly relates to more
than one of my sections.
My opinions are given in italics at the end of each Section with regard to their
relevance to urban sparrow decline (more particularly House Sparrow decline). Four
defining categories are used:
Consequent on Decline
Primary Factor refers to factors that relate directly to the bird: for example lack of
availability of invertebrates required to rear the chicks; whereas Secondary Factor
would be used for mechanisms causing the decline of invertebrates. It should be
noted that these are based on current information. The possibility of new evidence
should not be ignored. When electromagnetic radiation (emr) from mobile phone
masts was first suggested, it was greeted with derision both by biologists and
physicists. New findings, however, have given some support to the hypothesis. I have
recognised this by categorising emr as follows: Primary/Secondary Factor – both
might be relevant. Further investigation required.
List of Contents
1 Breeding Biology
1.1. Decrease in productivity
2.1 For food
2.2 For nest sites
3 Disease (parasites, pathogens)
3.1 Avian flu
3.5 Usutu virus (USUV)
3.6 West Nile Virus (WNV)
4.1 Increased cleanliness
4.2 Loss of cover
4.3 Loss of nest sites
4.3.1 Building repairs
4.3.2 Loft insulation
4.4 Type of urban environment
4.5.1 Disturbance/Road casualties
6 Farmland decline
7.1 Reduced availability of food in general
7.2 Reduced of availability of animal food for nestlings
7.3 Seeds: are fresh seeds necessary?
7.4 Unsuitable Food
7.4.1 Fast food discards
7.4.2 White flour
8.1 Electromagnetic radiation (emr)
8.2 Emissions from IC Engines
8.2.1 Diesel Exhaust Particles (‘Particulates’)
8.2.2 Unleaded petrol
8.3 Endocrine-disrupting Chemicals (edcs)
8.4 Heavy Metals
8.4 Light pollution
10 Social Effects
Figure 1. Plot of urban House Sparrow densities
1 Breeding biology
1.1 Decrease in productivity
Bower (1999), in a study in Hamburg, Germany, in 1997, found that none of the
broods that were started in April were successful. He suggested that this was because
of lack of insects essential for rearing the young.
According to the Nest Record Scheme organised by the BTO, the productivity of the
House Sparrow has decreased from 3.5 chicks fledged per brood in 1980 to 2.8 in
2003 (Crick et al. 2004). No differentiation of habitat is made in this analysis.
Vincent (2005), in an investigation covering nine areas along an urbanisation gradient
in Leicester, found that productivity was 25% lower in suburban areas than that of
farmland House Sparrows in Oxfordshire (Hole et al. 2002). Her conclusion was that
the main cause was the starvation of chicks during the early nestling stage. She found
that chicks were more likely to starve if they had a high proportion of vegetable food
in their diet. In June-July 2003, more young fledged where the foraging range (c. 100
m) contained a higher density of aphids1. Moreover, the body mass of the chicks that
fledged from suburban nests was lower than from rural ones. It was predicted that
only 57% of suburban fledglings would survive the first 10 days after fledging
compared with 70% from rural nests.
Peach et al. (2008), in an analysis of Vincent’s data, reported that brood body
condition at 2-6 days old was strongly negatively related to local atmospheric NO2
content and at 10 days still showed a marginally significant negative relationship.
Chick body mass at day 13 (viz. just prior to fledging) is a strong predictor of postfledging
survival probability. NO2 content is an indicator of atmospheric pollution by
exhaust fumes from IC engines. They observed that body mass at 10-12 days was
strongly related to the quality of chick diet, decreasing with the increasing proportion
of vegetable food in the diet.
As early as the 1970s, Seel (1970) demonstrated that nestling survival was directly
related to chick mass and related this to the availability of food.
[See Sections 4.2, 4.4, 4.5.2, 7.2, 8.2, 8.4]
1 Aphids (Hemiptera) are an important food item for young nestling House Sparrows (Summers-Smith
1963; Cramp & Perrins 1994).
2.1 For food
Bland (1999), in a survey of 135 1-km squares in Bristol, found that the 24
sparrow-rich squares were Feral Pigeon-poor, whereas of 62 sparrow-poor squares 20
were dominated by high numbers of Feral Pigeons Columba livia, Magpies Pica pica
or Carrion Crows Corvus corone. A possible conclusion is that there was real
competition between these species and House Sparrows, but no evidence was given
that any of these species had increased during the time of sparrow decline.
Dott & Brown (2000) concluded that competition by Feral Pigeons and Lesser Blackbacked
Gulls Larus fuscus did not seem to impinge on the life of the local House
Sparrows in Edinburgh in any way.
R. Zarrelli (in litt. 29.07.03) considered that increase of Collared Doves Streptopelia
decaocto could have been a possible factor in the decline of Italian Sparrows in an
urban park in Bologna, where it had been a common nester until 1980; by the end of
the 1980s the species had become very rare, disappearing completely in 2003. He also
informed me that in the city of Bologna encounters with the bird were becoming ever
more rare and occasional.
McCarthy (2003) reported that both Wood Pigeons (Columba palambus) and Collared
Doves have increased dramatically in Britain and are common in the suburbs and
some parts of towns, both competing directly for food with the House Sparrow, yet
both eat far more: a Wood Pigeon will eat about 53 g of grain a day and a Collared
Dove about 25 g, but a sparrow will eat only 9 g. He quotes G. Appleton, BTO, as
“It is possible their competition for the same food may be helping to cause the house
sparrow’s decline. . . . They do compete directly, more than any other species.”
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