COMMENTO CRITICO ALLO STATO DELLA “RICERCA” in U.K.
Più di due anni fa’ l’Università di Oxford promosse une Ricerca sulla Migrazione
della Beccaccia in Europa , così come puntualmente fu da noi sottolineato nel primo
Capitolo della “Beccaccia Scientifica “.
Purtroppo ad oltre due anni di distanza dobbiamo rilevare che per la Ricerca specifica
e per altri dati che si possono rilevare dal Web sembra a noi che ci sia molta
confusione , approcci non chiari, e soprattutto mancanza di un coordinamento globale
delle Ricerche in U.K. , pur rilevando iniziali esperienze di monitoraggio satellitare di
assoluto valore.
Questa nostra riflessione critica si documenta nei testi che qui di seguito riportiamo e
che sono stati da noi puntualmente riportati negli Aggiornamenti .
In particolare ci sembra “drammatico” l’appello della Ricercatrice di Oxford che a
due anni di distanza non sembra ancora in condizione di sapere da dove cominciare !
(N.B. – già in precedenza come potete verificare noi avevamo cercato un contatto per
conoscere lo stato della ricerca )
Tutto ciò ci sembra sconcertante poiché si sviluppa nell’ambito di Istituzioni di
Ricerca di un Paese che è stato ed è la culla del “birdwatching”. Anche le
contraddizioni di “census” ci appaiono rilevanti e forse è opportuno richiamare i
Ricercatori (tutti non solo quelli del Regno Unito , ma anche i Ricercatori di altre
Istituzioni Europee, magari anche quelli che poi gestiscono i “dati di census” nei
Documenti della Unione Europea ) a metodologie di rilevamento e di analisi
matematiche-statistiche quali emergono da importanti contributi quali quelli qui in
calce riportati .
Questa nostra Nota può forse apparire arrogante poiché espressa a livello di un
Website non inserito nel circuito Accademico ed Ambientalista , ma tant’è , è pur
sempre una riflessione libera che deriva da quanto oggi Internet può offrire per
meglio stimolare e coordinare le proposizioni delle Ricerche istituzionali .
Dilettantismo contro Istituzioni ? Può essere , ma può anche far bene .
QUI SEGUONO ALCUNI ESTRATTI DA “ LA BECCACCIA SCIENTIFICA” e
AGGIORNAMENTI , e da “corrispondenze” .
La Letteratura offre importanti e qualificati studi prevalentemente svolti nelle aree di
nidificazione e di svernamento : così tanti che hanno portato ad affermare che per
condurre un’adeguata politica di controllo venatorio la beccaccia può essere
considerata un uccello “sedentario” nell’areale Europeo ( Fadat C. 1989-2007;Ferrand
1989;Wilson 1979;Gossman e al.1979 – dal Forum sul Web di Amici Scolopax Rusticola ).
La validità ( “evidence based”) di questi studi – che appunto sono stati condotti in
aree fisse (riproduzione,svernamento) – è indiscutibile per le opportunità di
approfondimenti metodologici che ne sono scaturiti .
Ma è altresì innegabile che esiste tuttora una carenza di analoga approfondita ricerca
scientifica dedicata ai territori di transito migratorio .
Non è quindi fuori luogo sottolineare che l’Università di Oxford (UK) ha istituito e
finanziato uno studio – a partire dall’Aprile 2008 – dedicato a “Migration and winter
ecology of Eurasian Woodcock” dove il primo obbiettivo è “gain a better
understanding of woodcocks’ movements between breeding and wintering grounds
within Europe “ !!
Dato che questa iniziativa Universitaria è -ovviamente per Sede (UK)– dedicata alle
linee migratoria che interessano ,con modalità quasi esclusive , le Isole Britanniche ,
sarebbe auspicabile sollecitare analoga iniziativa per la Penisola Italiana .
Dear Dr Cavina,
This work us ongoing and not yet published. I am copying it to my doctoral student who is
undertaking the project as she might be able to give you more information.
Best wishes,
Dr Andrew G. Gosler
Edward Grey Institute,
Institute of Human Sciences &
Mansfield College, Oxford
Jun 9
Woodcock Research - Urgent Request
Written by Adele Powell
This is an appeal for assistance with a unique research project investigating the migration and
winter ecology of Eurasian Woodcock, Scolopax rusticola, which is being run in collaboration with
the University of Oxford and the Game and Wildlife Conservation Trust (GWCT).
The Eurasian woodcock is a cryptic, secretive wader and detailed knowledge of its migratory routes
and the linkages between breeding and wintering sites are still required. The aims of the study are to
1. Gain a better understanding of Woodcock movements between breeding and wintering grounds
within Europe, 2. Examine the separation of migrants from distinct breeding areas in NW Europe
across Britain and Ireland in winter, and their distribution relative to resident birds, 3. Determine
whether residency confers any fitness or survival advantage over migrants.
In order to address these aims, feather samples from birds of known origin (i.e. resident breeding
birds, shot/caught in the Spring/Summer/early autumn - from now, until end of Sept) are
required for analysis. I am in desperate need of samples from across the UK, Ireland and Europe,
and I was wondering if you could highlight my request to appropriate persons. Whether they be
hunters, forestry workers, bird ringers or someone just coming across a woodcock kill/carcass, it
would be hugely beneficial if persons could provide whole wing sample for analysis, but where this
is not possible then the 1st AND 10th primary wing feathers (smallest/innermost feather and
largest/outermost feather, respectively) will suffice. I've attached an image of the woodcock wing,
to help identify the correct feathers.
Alternatively, feathers may come from relatively recent museum specimens (again from birds of
know origin), where sampling is allowed.
Wing/feather samples from individual birds should be packaged separately, with details on bird age
(if possible), collection date and location, and the sender's contact details (including email address).
Samples should then be sent to the following address:
Miss Adele Powell
Edward Grey Institute of Field Ornithology,
Department of Zoology,
University of Oxford,
South Parks Road,
Oxford,
OX1 3PS
United Kingdom
I hope you can help. If not directly, then maybe you could pass on my details to other contacts you
may have, as I am in DESPERATE need of samples from across Europe.
I would really appreciate your support.
Kind Regards
Adele Powell
Office: UK 01865 271173 begin_of_the_skype_highlighting
271173
end_of_the_skype_highlighting
01865
Mobile +447748833430
begin_of_the_skype_highlighting
E-mail: [email protected]
+447748833430
end_of_the_skype_highlighting
Edward Grey Institute of Field Ornithology
University of Oxford,
South Parks Road,
Oxford OX1 3PS
Densities and population estimates of breeding Eurasian
Woodcock Scolopax rusticola in Britain in 2003
Authors: Andrew N. Hoodlessa; Deborah Langb; Nicholas J. Aebischera; Robert J. Fullerb; Julie A.
Ewalda
Affiliations: a Game & Wildlife Conservation Trust, Hampshire, UK
b
British Trust for Ornithology, The Nunnery, Norfolk, UK
DOI: 10.1080/00063650802674768
Publication Frequency: 4 issues per year
Published in:
Bird Study, Volume 56, Issue 1 March 2009 , pages 15 - 25
Subjects: Animal Behaviour; Animal Ecology; Animal Physiology; Animal Taxonomy;
Biodiversity; Environmental Geography; Marine & Aquatic Science; Natural History - Evolution
and general biology;
Formats available: HTML (English) : PDF (English)
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Abstract
Capsule The breeding Eurasian Woodcock population in Britain was estimated at 78 346 males
(95% CL 61 717-96 493), with substantial differences in densities between regions and woodland
type.
Aim To estimate the breeding population size of Woodcock in Britain using a dedicated survey
method, to enable assessment of current status and the creation of a baseline for future monitoring.
Methods Passes of roding male Woodcock were recorded on three evening visits to 807 randomly
selected sites, stratified by region and woodland size, by volunteer observers during May-June
2003.
Results Roding Woodcock were present in 35% of 1-km squares containing at least 10 ha of
woodland and the mean density of males in occupied squares was 2.76 ± 0.29 birds/km2 (± se).
There was significant regional variation in the occurrence and density of roding Woodcock.
Woodcock presence differed between woodland types at the 1-km2 level and the stand level, but
densities within occupied woods were similar across woodland types.
Conclusion Previous estimates of the size of the British breeding Woodcock population are far too
low and the species shows much spatial variation in breeding density.
view references (44)
from ENGLAND
Woodcock 5-10 times more numerous than previously thought
March 2009. The woodcock is an elusive wader that was amber listed in 2002 because of an
apparent decline in its breeding population. Although in autumn the resident UK woodcock
population is supplemented by a large influx of up to 750,000 migrants from continental Europe,
very little is known about this secretive bird. To help inform future management and hunting
policies, the Game & Wildlife Conservation Trust has embarked on an ambitious research
programme to discover the status of different woodcock populations.
British woodcock population
Initially, this research involved determining the status of the British woodcock population. To do
this, the Trust developed a unique species-specific survey method that enabled researchers to more
accurately count this elusive nocturnal bird. As a result of this new monitoring technique, the Trust
has revised the population estimate to 78,500 pairs from the original suggested population of just
5,000 -12,500 resident pairs.
Annual counts
Although the survey revealed that the population was actually much higher than originally
estimated, it is important to determine whether there has been a serious decline in resident
woodcock numbers from previous levels. Annual counts are ongoing and a repeat national survey is
planned in order to address this.
Migration from Scandinavia & Russia?
As well as studying our resident birds, the Game & Wildlife Conservation Trust is working with
Oxford University to look at woodcock migration in Britain and Ireland. Dr Andrew Hoodless, who
heads this research for the Trust said, "Although woodcock breed across Scandinavia to northern
central Russia, our current knowledge of the origins of migrant woodcock in Britain and Ireland is
based on just 290 recoveries of foreign-ringed birds over the last 100 years. We therefore need to
build a more detailed picture of the links between breeding and wintering sites and of migratory
routes so that we can evaluate the effects of changes in habitat, climate or hunting pressure at stopover or wintering areas at the population scale."
Chemical research
The Trust's new research aims to incorporate information from a variety of sources to build a more
complete picture than has been previously possible. Using the facilities offered by Oxford
University, the Trust will be analysing the stable isotopes of elements such as hydrogen, carbon and
nitrogen, which are locked into the birds' feathers as they grow on breeding grounds. This offers a
unique insight into the region of origin of each individual bird.
Satellite tags reveal 4000 Kms journey
The Trust is also investigating the use of satellite tags on a small number of woodcock to provide
detailed information on routes between wintering sites and breeding grounds, to complement the
information obtained from stable isotope analysis. Tagging can provide invaluable data on
woodcock migration and a study in Spain recorded a female woodcock that migrated 3,800
kilometres to Russia to nest in 2007, returned to within 11km of the original point of capture in
Spain during the winter of 2007/8 and nested in Russia again in 2008!
Hunting community
In addition to these technological developments, which will be invaluable in assessing the current
status of woodcock, the Trust is enlisting the support of the shooting community, Andrew Hoodless
explains, "We believe that the shooting community can provide valuable information on woodcock
arrivals and movements. Wings collected from shot birds can be used to provide an insight into
whether there are regional differences in the timing of arrival of the different ages and sexes. Bag
records have not been used to their full potential for this species and we think they can reveal a lot
about the effects of weather and regional differences in woodcock abundance. From this
information we will be able to model potential future changes in woodcock numbers and
distribution based on different climate change scenarios."
Generous funding by the Countryside Alliance Foundation and the Shooting Times Woodcock Club
has enabled the Trust to employ a PhD student, Adele Powell to carry out this essential research.
The Trust has also initiated its own Woodcock appeal, and those interested in woodcock research
are invited to donate £65 to cover the cost of sponsoring an individual woodcock, thus enabling a
more detailed analysis of its migratory habits.
The woodcock has long been prized as an elusive and challenging species. This sporting interest
inspired numerous studies. The first was led by the 6th Duke of Northumberland, in 1891. Today
we have the technology to analyse individual feathers in the race to demonstrate the stability of our
resident woodcock population.
Our research with other gamebird species has shown that the habitat management and predation
control that is part of game management actually enhances the conservation status of a bird.
Dr. Andrew Hoodless, leader of the Game & Wildlife Conservation Trust's woodcock project, is
one of our senior scientists and a recognised expert on the woodcock (Scolopax rusticola). Dr
Hoodless is to carry out a detailed study of woodcock migration.
The woodcock was amber listed as a bird of conservation concern in the UK in 2002 due to an
apparent decline in its population. This immediately made conservation agencies in the UK and
Europe question whether the bird should remain on the UK quarry list.
The Game & Wildlife Conservation Trust's woodcock survey method, which is based on sightings
of roding males at dawn and dusk, has produced a new population estimate of 78,000 pairs. This
new method is now accepted as best practice and will form the basis of a second national population
survey, 10 years after the first, in 2013. The uplifted estimate has alleviated some of the concern,
but we still have no way of knowing how shooting pressure impacts on our resident woodcock
population, as opposed to our winter migrant population.
To complete the picture we now need to do a second study, to establish how many of the birds shot
in the UK are part of our resident population and how many are not. This work may secure the
woodcock's position on our quarry list. Dr Hoodless proposes to carry out his count by the
examination of isotope signatures within woodcock feathers. This will enable him to establish the
birds summer breeding grounds and the timing of migration. In turn, this will complement the long
term data that he already holds from "ringing returns".
Understanding our resident woodcock numbers
Our new research will examine feathers from young birds recovered from shoots around the country
to establish where each woodcock originated from. Through understanding what proportion of
woodcocks in the bag are migratory we can provide the answers we need.
Analysing the feathers
The Edward Grey Institute at Oxford University has kindly given us access to their laboratories.
Their equipment is now so sensitive that we will be able to combust the tip of a feather and analyse
the atoms. In essence, the isotope work involves vaporising the atoms in the feathers and through
analysis of the isotopic constituents, we can then tell which country or region they have come from.
These facts will form a vital part of the jigsaw we need to conserve woodcock. Without the
evidence we will be just guessing.
The amazing migration
The woodcock is an elusive and cryptic wader. It is in autumn, when our
resident birds are supplemented by a large influx of migrants from continental
Europe, that most woodcock are encountered. Even now, one is seldom
treated to more than a fleeting glimpse of the bird as it jinks away through the trees.
The autumn migration provides an amazing spectacle as some 740,000 woodcock migrate to the
UK in small flocks, landing on our eastern coastline from Aberdeen to Folkestone. Migrants
usually start arriving during the second week of October. Shooting literature suggests that large
falls often occur around the time of the full moon in late October and particularly in November, the
latter being regarded as 'the woodcock moon'.
The largest number of woodcock recorded at any of the observatories tends to be the Fair Isle,
where about 50 per day are seen during peak passages, although more than a thousand were
recorded on 27-28 October 1976. The birds have escaped harsh winters and travelled from Norway,
Sweden, Finland or as faraway as Russia and Latvia.
Please help us with our critical research by making a donation of support
You can help us to complete this critical piece of research by making a donation of support. A
donation of £65 will cover the cost of sponsoring an individual woodcock so that a detailed analysis
of its migratory habits can be made.
The Trust will be holding two presentations by Dr Hoodless in February and March. For further
information please visit our events calendar.
How many woodcock?
Key findings



More than 900 woods were surveyed across Britain for the Breeding Woodcock Survey.
Woodcock were present at 44% of sites and densities in occupied woods averaged 4.17
males per square kilometre (100 hectares).
There was regional variation in the occupancy of woods and abundance of woodcock, the
general pattern being of higher numbers in southern Scotland, northern and eastern England
and relatively low numbers in Wales and south-west England.
During May and June 2003, with the British Trust for Ornithology (BTO), we ran the first national
survey of breeding woodcock in Britain. Owing to its secretive behaviour and activity at dawn and
dusk, there has long been uncertainty about the woodcock's status as a breeding bird, although
information from general bird surveys organised by the BTO pointed to a decline. For our survey,
we devised a method based on counts of roding males at dusk (see Review of 2003).
'Roding' is the term given to the distinctive display flight of males during the breeding season.
Three counts were made by volunteer observers at points within the wood that gave good visibility.
Observers made counts in randomly-selected one-kilometre squares that were stratified by region
and woodland area, although a small number of non-random sites were included. The basic unit of
abundance was the number of passes of roding woodcock during one hour at dusk. This was
converted to an estimate of the number of individual males based on earlier calibration work (see
Review of 2003).
The survey was a great success, with counts from 937 sites. We now have a basis for monitoring
future population change, with a good sample in each region of Britain. Overall, the frequency at
which woodcock occurred in woods was encouraging, with roding birds recorded in 416 (44%) of
the woods visited. However, at most sites woodcock were present only at low densities (average
4.17 roding males per 100 hectares) and only 5% of occupied sites had more than 10 roding males
per 100 hectares. There was appreciable variation between regions in the occupancy of woods and
abundance of birds. This was one of the most striking findings of the survey, showing that
woodcock are far from evenly distributed (see Figure 1).
Figure 1. Boundaries
of regions used for the
woodcock survey and
mean densities for all
sites surveyed
including zero counts
(males per 100 hectare
square containing at
least 10 hectares of
woodland). Regions
were selected on the
basis that each
contained similar
amounts of woodland
within four size classes.
The occupancy of woods was highest in eastern England where woodcock were reported in 72% of
woods and was lowest in Wales with birds recorded in just 20% of woods (see Figure 2). Regions
with low rates of occupancy also had low densities of woodcock within occupied woods, with
Wales as the lowest (average 1.73 roding males per 100 hectares). The highest densities within
occupied woods (more than four males per 100 hectares) were found across southern Scotland,
northern England and the north Midlands down through eastern England into East Anglia. Central
southern English counties also contained high densities.
The regional pattern of woodcock abundance in our survey largely mirrors that depicted in the BTO
atlas, but there are two notable differences. South-east England and Dumfries and Galloway no
longer appear to be hotspots for the species and there may have been declines in these regions in the
last 15 years.
Figure 2. Regional rates of woodcock occurrence (percentage of surveyed
woods where woodcock were recorded)
So what size is the British woodcock population? Using our estimates of male woodcock density in
one-kilometre squares for 11 regions we can extrapolate to regional estimates of numbers from the
total number of one-kilometre squares within each region containing different proportions of
woodland. This gives population estimates of 21,000 males for England, 18,000 males for Scotland
and 1,000 for Wales. If it is assumed that there are similar numbers of females, the total number of
breeding woodcock for Britain is approximately double that estimated in the BTO's New Atlas of
Breeding Birds 1988-91.
We thank all the volunteers who participated in the survey and the BTO Regional Representatives
who organised the coverage. We are grateful to the Shooting Times Woodcock Club and an
anonymous English charitable trust for funding the survey.
SCOZIA – Anche in G.B. iniziano le ricerche sulla migrazione con RadioTelemetria SATELLITARE – I primi risultati evidenziano tutti i movimenti
delle beccacce dall’Isola di ISLAY fino in Russia . Le immagini e le mappe sono
molto dettagliate . REFERENTE : [email protected]
APPARE EVIDENTE CHE LE RICERCHE SULLE MIGRAZIONI SI ORIENTANO
SEMPRE PIU’ ALL’UTILIZZO DELLA RADIOTELEMETRIA SATELLITARE .
11 00 3000
The fantastic information from the two Islay woodcock suggests that we need to satellite track more
woodcock, especially from other parts of Scotland to compare migrations, and we would also like to
mark a few Scottish breeding woodcock to check on their migration and wintering behaviour (most
likely to Ireland). The winter migrants need to be tagged in February 2010 and the local breeders in
August 2010. Please get in touch with me if you would like to fund a transmitter, or transmitters,
may be on your own land or woodcock hunting area, to discuss opportunities. Email:
[email protected]
10 00 3000
Tracking woodcocks from Islay in the Inner Hebrides
An exciting new project
Several years ago, Chloe Randall, the Manager of Dunlossit Estate on the island of Islay, asked me
to give the estate additional advice on the use and importance of traditional cattle for nature
conservation benefits on Dunlossit. I visited Islay and was shown the operation of the farming
enterprise, in particular their work with traditional cattle and free-range pigs. I walked over large
areas of the estate and agreed with their plans, but also suggested a greater change to traditional
cattle, Galloway, blue-greys and Highlanders, and a suggestion that these cattle should be
encouraged to graze more widely on the estate. This would help with the ecological restoration of
grasslands that had become rank and overgrown, and would enhance the conditions, once pigs had
grubbed up the worst areas of bracken. Not only could the traditional livestock produce high quality
conservation meat but would also have major benefits for biodiversity. Of special interest on the
Dunlossit grasslands are chough and various breeding waders, and in winter Greenland whitefronted geese and woodcock.
09 00 3000
Askaig migrated to northern Russia to breed (see he migration details on the Askaig webpage). The
migration journey (point to point of her locations) was an amazing distance of 4093 kilometres
(2543 miles).
08 00 3000
Dunlossit
The trustees of Dunlossit Estate showed great interest in the biodiversity benefits of traditional
grazing, and during discussions one species, which was of special interest to them, was woodcock.
Dunlossit woodlands have a small population of breeding woodcock, and one evening when I was
there, we went out at dusk and saw several displaying males - flying over the woodlands giving
their distinctive roding calls. There is also a larger winter population which arrives in late October
and November, and is an important quarry for hunters. It was assumed these birds came from
northern Europe, and I thought that the local breeders migrated to Ireland for the winter, and there
might be other populations present or passing through. They are an interesting and enigmatic
species - and Dunlossit is interested in their conservation and the good management of their habitat.
Club de Cazadores de Becada
During our satellite tracking studies on raptors, we hear of other projects or meet other researchers.
One project which particularly caught my attention was the capturing and satellite tracking of a few
woodcock in Spain. This was carried out by Joseba Felix Tobar-Arbular and the Club de Cazadores
de Becada, the woodcock hunting association in the Basque country in northern Spain. One of the
woodcock they had caught and satellite tagged, named Navarre has migrated twice to Russia and
back to Cantabria, and provided amazing insight into woodcock migration. I was very impressed by
this bird, and got in contact with Joseba, who was most helpful and told me much about their
project (Scolopax Sin Fronteras - Woodcock without Frontiers) and the satellite transmitters. This
included a new type of 9 gram solar powered satellite transmitter designed by Microwave
Telemetry.
Dunlossit Estate were also very excited by the travels of the Spanish birds and offered to fund two
transmitters, which were designed for woodcock migration by Paul Howey of Microwave
Telemetry. I decided to wait until after the end of the woodcock hunting season in 2009 before
trying to catch some for study.
Catching Woodcock
To catch woodcock for ringing you use a spotlight and a large butterfly net, you need a really dark
night, preferably at the time of new moon, with overcast clouds and hopefully raining, and a lot of
luck. It's an exciting trapping technique which I remember from my years as Warden at Fair Isle
Bird Observatory. I decided to go to Islay on 24th February, as the new moon was next day. Donald
James Macphee, the head keeper on Dunlossit showed me the best places for woodcock, and that
night we set off - some of those best places held no woodcock at night, so we tried new locations
and saw 3 birds but caught none, our only success was catching a snipe. Next day, gave me a
chance to check where the woodcock were in daytime in the woodlands, then at 8pm Donald James
and I set off for new pastures, where the cattle were grazing in a valley, and we caught three
woodcock out of five in about an hour in blustery conditions. The two heaviest were fitted with
satellite transmitters and the other was ringed and released. I chose the heaviest birds as I thought
they would be the most likely to be ready for migration to Europe, rather than returning local
breeders (with fingers crossed). I decided to call them Lossit and Askaig - two local Islay place
names. Already, we can see that the woodcocks prefer to feed at night on the grasslands grazed by
the traditional cattle, because those are the best places for them to find their favourite food earthworms - which are in the older cowpats! So the projects of good cattle grazing and woodcocks
join together.
Migration. In late March, they suddenly decided to leave Islay and their migrations are shown on
separate pages - Click on the left buttons to check out the two woodcock's migrations.
Remember that these tiny radios are not GPS accurate like the larger ones on ospreys and eagles, so
that there will often be times when the signals are inaccurate and can only give a rough idea where
the bird has reached. Also remember the lines joining the fixes are not necessarily the track of the
migrating woodcocks, it is just a convenient way of joining the migration positions.
Check www.ccbp.org/home.htm for the Spanish studies
INDIRIZZO per vedere tutti i movimenti della Beccacce Scozzesi
http://www.roydennis.org/birds/index.asp?id=146#thumb
LAVORI SCIENTIFICI altamente specialistici , consultabili da
RICERCATORI , altrimenti di difficile comprensione .
1 - Steinar Engen e coll. :Migration and spatiotemporal variation in population
dynamics in a heterogeneous environment
Ecology ( Journal Ecological Society of America ) , p.570 , 2002
Questo lavoro molto specialistico evidenzia metodi di studio matematico statistico
per comprendere le variazioni spaziali ( e quindi territoriali) in sincronia con le
fluttuazioni di abbondanza delle single specie migranti . Di fatto questi metodi
possono essere applicati per approfondire l’entità di aumento o diminuzione di una
popolazione di uccelli migratori ( beccaccia inclusa) in un determinato territorio
osservando appunto le fluttuazioni , che sono note a tutti i “migratoristi” .
2- vol. 167, no. 3 The american naturalist march 2006
E-Article
Migration and the Genetic Covariance between
Habitat Preference and Performance
P. Nosil,1,* B. J. Crespi,1,† C. P. Sandoval,2,‡ and M. Kirkpatrick3,§
Quì sono prese in considerazione le varianti e variazioni genetiche