Euring Brochure 2007

Bird Ringing for
Science and Conservation

EURING
The European Union for Bird Ringing

Bird Ringing for Science and Conservation Bird Ringing for Science and Conservation

Preface What is Scientific Bird Ringing?

We live in a rapidly changing world highly trained ornithologists to provide vi- Scientific bird ringing is a research method Much of the data for this work are gath-
where human activities are causing rapid tal data on migration patterns, demogra- based on the individual marking of birds. ered by well-trained ”professional ama-
declines in many species of animals and phy and ecological processes. We are for- Any record of a ringed bird, either through teurs” whose motivation is not money but
plants, linked to widespread environmen- tunate that many volunteers contribute recapture and subsequent release, or on the simple privilege of working with birds
tal change. Within a few decades it is pre- to this activity, allowing us to study pop- the occasion of its final recovery as a dead for the ultimate purpose of conservation.
dicted that global climate change will ulations at large spatial scales. In Europe bird, will tell us much about its life. This Because almost 4 million birds are ringed
bring about even greater changes than we these activities are organized by national technique is one of the most effective annually in Europe alone and because
have seen so far. Action to address these ringing centres in each country, co-ordi- methods to study the biology, ecology, be- many birds migrate freely across political
issues must be based on sound science. nated by EURING. This brochure explains haviour, movement, breeding productivity boundaries, the use of individual rings and
Information concerning the status of our how these activities are contributing to and population demography of birds. the collection of data from birds recov-
wildlife resources is needed for effective conservation science, and how they can be Tracking back the journeys of ringed ered need efficient organisation. A net-
targetting of conservation action, while developed further to address some of the birds allows us to define their migratory work of fully co-ordinated ringing stations
robust understanding of ecological proc- conservation challenges of the 21st cen- routes and staging areas, so providing cru- and National Ringing Schemes has been
esses is essential for predicting the effects tury. We hope that it will provide a useful cial information for the planning of inte- indispensable for the management of sci-
of policy and management actions. overview for conservationists, policy mak- grated systems of protected areas for our entific bird ringing in Europe. EURING, the
Birds are excellent tools for monitor- ers and environmental scientists, and that birds. Other information derived from re- European Union for Bird Ringing, guaran-
ing and understanding environmental it will also be of interest to all those who coveries and recaptures include popula- tees the efficient collaboration among na-
change, as well as being a charismatic are concerned about how and why our tion parameters (e.g. survival estimates, tional ringing schemes.
wildlife resource that brings enjoyment bird populations are changing. lifetime reproductive success), which
to many millions of people. Bird Ringing are essential to determine the causes of
involves the marking of individual birds by Stephen Baillie, Chairman of EURING changes in population sizes.
Matthias Kestenholz

Marcel Burkhardt
Bird ringing data are useful in both
research and management projects. Indi-
vidual identification of birds makes pos- The main aim of ringing is to gain results
sible studies of dispersal and migration, which can be used in research and man-
behaviour and social structure, life-span agement. Ringing is not a goal in itself,
and survival rate, reproductive success but a scientific method of collecting de-
and population growth. sired information on the life of birds.

1


Birds are personalities Outstanding individuals

Individuals of the same species and sex relations among several behaviours of the Ringing birds individually allows us to fol- 25,000 kilometres. Measured as straight
have behavioural and physiological dif- same profile, (3) ontogenetic studies on low even the most exceptional personal line distances, the tern’s journey is “only”
ferences, even in standard conditions. In plasticity and environmental malleability, fates. 17,508 km.
humans, many of these differences are and (4) field studies on survival and re- The oldest wild bird ever recorded could The rate of migration is quite differ-
treated as expressions of individual vari- production towards understanding how be a Manx Shearwater captured on a lit- ent from that attained in flights for short
ation in personality. Yet in other animals, different types of personality are main- tle island off north Wales. The venerable distances. The fastest journey is from a
such explanations have often been ne- tained. bird was first captured and ringed by or- ringed European Barn Swallow Hirundo
glected, the differences interpreted in- Different personality types may react nithologists in May 1957, when it was full- rustica that flew in 27 days from Umh-
stead as either the consequence of inac- differently to environmental changes grown, hence between four and six years lange, Kwa Zulu Natal, South Africa, to
curate measurements or as non-adaptive and may show differential vulnerability old. It had been caught in 1961, 1978 and Whitley Bay, United Kingdom.
variation. to stress, leading to differences in welfare. 2002, when a warden of the Bardsey is- A Black-headed Gull was ringed as a
Putting a ring to a bird’s leg makes the Ultimately, such differences can have ma- land Bird Observatory caught the seabird fledgling on 29 June 1996 in Hämeenkyrö
bird a recognizable individual whose in- jor impacts on individual fitness, response again. The shearwater‘s possible age of 52 county, Pirkanmaa, Finland. The metal ring
dividual life history and fate can be fol- to environmental change, geographic dis- years could make it the record holder. Un- was sighted with a telescope on the 3 and
lowed. Personalities are general proper- tribution, and even rates of speciation. til now, the world‘s oldest ringed bird was 7 January 2000 in Fort Worth, Texas, USA.
ties of birds, other animals, and humans. a US albatross estimated to be over 50. The bird was back again to its wintering
Recent studies in birds suggest that ani- One of the longest journeys ever re- quarters in Texas on 30 November 2000.
mal personality can be studied objectively. corded is from a Common Tern ringed
Such work has used four approaches in on 27 June 2003 as a nestling in Hälsing-
parallel: (1) descriptive studies, including land in central Sweden and found dead
the investigation of links among several on 1 December 2003 on Stewart Island in
behaviours and their specificity across sit- New Zealand. If we assume a normal route
uations, (2) genetic and physiological re- from Sweden to South Africa and then to
search on causal mechanisms underlying New Zealand, the tern might have covered

Helmut Kruckenberg

Steve Stansfield

Beat Walser
Special rings and various other marks can be used to identify birds at a distance The old Manx Shearwater must have Common Terns migrate between the two
without needing to catch them again. These White-fronted Geese were marked with flown at least eight million kilometres hemispheres and, by this, experience both
colour neck bands, each individually identified by numbers or letters. during its long life. northern summer and austral summer.

2 3


Viborg Stiftsmuseum

Joël Krebs

Matthias Kestenholz
Methods of bird ringing

Many birds are ringed as chicks in nests
but fully-grown birds have to be caught
using a variety of nets and traps. What-
ever the catching method, ringers are
carefully trained to ensure the safety
of the birds they ring. Small birds are
often caught in fine mist-nets. Bigger
birds, such as ducks, are often caught
in “walk-in” or baited cage traps. Af-
ter removal from a net or a trap, birds
are usually placed in soft cotton bags
or in special holding boxes where they
remain quiet and dry until they can be
identified, ringed, examined and re-
Many birds like this Tawny Owl are
leased.
ringed as chicks in nests.
Special rings and various other marks
can be used to identify birds at a dis- Bird ringing for scientific purposes started
tance without needing to catch them in Denmark in 1889, when H. Chr. C.
again. Many birds wear colour rings with Mortensen released Starlings that were A row of mist-nets at the bird ringing
numbers that can be easily read through fitted with metal rings engraved with site Col de Bretolet in the Swiss Alps. By
a telescope. Waterbirds can be marked successive numbers and a return address. co-ordinating the activities of ringing
with colour neck bands, and larger birds Since those pioneer times, bird ringing stations throughout Europe and Africa,
marked with wing tags, each individu- quickly evolved into a standard research EURING is helping to unravel the myster-
ally identified by numbers or letters. technique used in all parts of the World. ies of bird migration.

Waterbirds like ducks are often caught in baited cage traps.

Geert Brodvad

Matthias Kestenholz
A wide variety of
ring sizes is used
to mark different
species, depending
on the dimension
and structure of
the leg and the
habitats the birds
live in. The weight
increase to the
bird from the ring
can be roughly
compared to that
of a wristwatch
for a human.

4 5


Kurt Pulfer
Satellite tracking
One method that has added a new dimension to avian research in recent years is satellite
tracking. Tiny transmitters, usually carried in harnesses strapped to the birds’ bodies,
are linked to satellites. Each harness is custom-designed for each species and manually
adjusted for each bird for maximum comfort of fit. The system enables researchers and

Kurt Pulfer
conservationists to track individual birds continuously.
The results achieved by satellite tracking are ground-breaking. For the first time, the
whole spatio-temporal pattern of successful migrations can be captured at a level of
detail far exceeding that provided by ringing. Satellite tracking can also help discover un-
known breeding, moulting or wintering areas of endangered species or causes of massive
losses. When combined with other devices, such as thermometers or miniature cameras,
additional information of the bird’s behaviour may be transmitted to the satellite.
However, satellite tracking will never replace bird ringing. The reasons for this are
simple: transmitters are relatively expensive, a large amount of technical equipment is
necessary, and the technique is limited to larger species (though transmitters now weigh
Mist-nets are made of very thin nylon
as little as 10 g).
threads and are cheap and safe for
EURING will incorporate data from satellite tracking into its database in order to ensure
catching small birds, such as this male
that these extremely valuable data are stored in perpetuity.
Lesser Redpoll.

www.piskulka.net
An individually numbered ring is closed
around the leg of a Hawfinch using spe-
cially produced ringing pliers.
Kurt Pulfer

Ingar Jostein Øien
Kurt Pulfer

Close scrutinity of the details of plumage The Lesser White-fronted Goose is at present one of Europe‘s most endangered
may allow the ringer to identify the age bird species. The most important single threat throughout it’s range is the high
and sex of the bird in the hand. mortality due to hunting and poaching. The core problem was, and partly still
is, that the staging and wintering grounds for the species are virtually unknown.
To locate them, a few individuals from the Fennoscandian population were
equipped with satellite transmitters. They revealed a loop migration from the
Measuring a particular primary feather
Norwegian breeding sites to the moulting area in arctic Siberia, and the winter
gives a good indication of overall size of
quarters in Greece.
an individual bird.

6 7


EURING
Bird ringers and ringing centres

By definition, “bird ringers” or “ringers” spare time, as voluntary work. Most of
possess a ringing licence. Though the exact the ringers are involved in co-ordinated
way of becoming a ringer and gaining a li- projects, following the welcome general
cence differs from country to country, the trend of designed projects in bird ring-
basic principles are the same everywhere. ing. Without the help of these volunteers,
Every examinee has to demonstrate his it would be impossible to work ringing
knowledge of bird identification, of sex- stations and maintain centrally co-ordi-
ing and ageing, the practical and admin- nated projects, such as Constant Effort
istrative details of ringing, and, last but Sites, national and international species- 12 000
50 315 000
not least, the ethical and conservational orientated projects. From the dawn of 250
aspects of this research method. bird ringing, many millions of records
In most countries, trainee ringers have have been gathered from all over the 220 000
700
to spend a number of years of practice be- world mainly by those tens of thousands
240 000
fore ringing on their own. These years of of dedicated volunteers. This enormous 350
probation and the ringing courses are of field work, together with the invaluable
great importance in acquiring the meth- help of all the informants, forms the basis 110 000
90
ods of safe handling of the birds and the of the numerous books, and publications, 250 000
equipment, becoming experienced in the describing most of our recent knowledge 70 groups
15 000
200
70 000
identification of the different, common of bird migration. 175 90 000
and uncommon species. Also it takes a Bird ringing is organized by national 50
few years to meet all the specific, rarely- ringing schemes. The responsibility of the 6 500
880 000
220 000 35
used capturing methods and to become national ringing schemes is to co-ordinate 2100 350 000 50 000
460 830 200
skilled in measuring the birds. and canalize the ringing activities. The 700 000
The form and the content of the ring- role of EURING is to co-ordinate analyti- 374
150 000 25 000
ing licence differ according to varying cal and field projects at a continental or 450
8 000 27 000
20 52
legislation in the various countries. Ring- flyway scale, and also to facilitate stand- 200 000
180 000
90 000
400
ing on strictly protected areas or captur- ardization and the exchange of technical 260
230 5 500
50 000 60
ing endangered species usually requires information. Processing data gathered in 50
12 000
special licensing and can only be main- this way, on a wide geographic scale by 38 000
46
40 15 000
tained by experienced ringers engaged in standardised methods, gives a much more 450
380 000
a particular species-conservation or study detailed picture of bird migration, disper- 200 000
762
15 000 400
program. Moreover, some ringing centres sion and population trends. Regular feed- 133 15 000
1 000
7
10
allow ringing only for well-designed, ac- back and publication of the results is es-
cepted conservation programs. sential for the thousands of volunteers.
Only a fairly small proportion of ringers 12 000
are professional scientists. They are em- 20
ployed mainly by universities, using bird
ringing in special research programs. A
very small number of ringers are employ-
ees of ringing stations or field assistants
of certain conservation projects. The numbers of birds ringed annually and the numbers of ringers licensed by each
Non-professional ringers form the ma- ringing centre. If several ringing centres operate in one state, summary figures are
jority (around 70 %) of the ringers’ com- given. It is estimated that 115 million birds have been ringed in Europe during the
munity, and perform this activity in their 20th century and the number of recoveries now exceed 2 million.

8 9


EURING – The European Union for Bird Ringing

Birds do not respect national boundaries, High-quality, quantitative methods are ringing programme is being developed to and strategies, survival and dispersal rates,
so international co-operation is required in essential for research based on bird ring- give annual changes in abundance, pro- the impact of human activity on bird pop-
order to study them effectively. EURING is ing. For this reason, EURING encourages ductivity and survival for many species. ulations and the impact of bird activity on
the organisation which enables co-opera- the development of statistical techniques The EURING Data Bank (EDB) was estab- humans. Data have been supplied to ama-
tion in all scientific aspects of bird ringing and computer software specifically to han- lished in 1977 as a central repository for teur researchers, research students, profes-
within Europe. All European bird ringing dle the particular problems involved in the European ringing recovery records. Until sional ornithologists and research organi-
schemes are members. The EURING Board analysis of data gathered through bird 2005, it was hosted by the Netherlands In- sations. Many papers have been produced
(Chairman, Vice-chairman, General Sec- ringing. EURING organises technical con- stitute of Ecology. It is now held by the Brit- using the data.
retary, Treasurer, and from three to five ferences every few years attracting spe- ish Trust for Ornithology. Recovery data are The EDB is also compiling archives of
other members, all elected by the ringing cialists from all over the world. They have, made available to many researchers. Data annual totals, by species, for all ringing
schemes) meets at least once a year. A gen- so far, concentrated on the use of ring re- have been used to study a wide variety of schemes; of data supplied to researchers,
eral meeting, for representatives from all covery data for research on avian popula- aspects of ornithology – migration routes and of publications using EDB data.
the schemes, is held every two years. tion dynamics.
EURING was founded in 1963. By 1966 Through pan-European ringing projects,
it had defined and published the EURING we can increase understanding of bird pop-
Exchange Code allowing easy data trans- ulations. EURING organises projects which
fer between schemes and simplified data can involve many ringers across the con- EDB Holdings
analysis. Developments in technology al- tinent. For example, the Swallow Project
Total number of records 4,743,373
lowed an enhanced version of this code to aims to discover more about the species‘
Total number of species 485
be published in 1979 with further develop- breeding, migrating and wintering strat-
Number of species with over 10,000 records 87
ment of the code 2000. egies. A European-wide constant effort
Number of species with 1,000 to 10, 000 records 119
Number of ringing schemes submitting computerised recovery data 28

Mark Grantham
How to obtain data from the EDB?
Full details of the EDB dataset and the system for applying to analyse data from the EDB
are available on-line. http://www.euring.org/edb

Achievements of EURING
• Undertakes applied analyses of ringing data at a European scale
• Co-ordination of a network of over 500 Constant Effort Sites throughout Europe
• Promotes European-wide research projects involving networks of volunteer ringers
• Promotes the development of statistical and computing methods for the analysis of
ring ringing data.
• Provides guidelines and standards for bird ringing
• Devised a standard code for the computerisation and exchange of ring recovery data
• Established the EURING Data Bank
• Facilitates communication between schemes, ringers and members of the public
through its website
The EURING Data Bank is hosted by the British Trust for Ornithology at Thetford, UK.

10 11


Sergio Tirro
Understanding Bird Migration – The Need for Bird Ringing

A flying bird can quickly move long dis- short distances, while others can migrate
tances and this makes it possible to mi- vast distances to wintering areas in the
grate regularly between areas that are southern hemisphere. Some species move
suitable during different periods of on broad fronts while others follow very
the year. In areas with strong seasonal- narrow routes. Irruptive movements occur
ity, migratory birds can successfully take in several northern species in response to
advantage of a short but very produc- food shortage.
tive summer to breed and raise young. The original purpose of bird ringing was
At northern latitudes, such as northern to unravel the mysteries of bird migration.
Europe, most of the breeding bird species Within Europe the broad patterns of mi-
are migratory and leave for some period gration are now known for most bird spe-
of the year. In most areas of the world, cli- cies. In recent decades the member coun-
mate and/or food availability varies over a tries of EURING have greatly intensified

after Zink and Bairlein 1995
year. This means that annual movements, their efforts in the area of migration re-
in order to increase survival, can be advan- search. The computerisation of the ar-
tageous everywhere. Migration is a most chives of recovery data has been a pre-
important key to the large and fascinating requisite for many of the recent recovery
diversity of birds in the world. analyses and also for producing national
The variation in migratory behaviour recovery atlases. Comprehensive atlases Parallel and narrow migration routes
is extremely large; some birds move only have been published in several member shown by different populations of
Chaffinches ringed during passage at
two bird observatories in Europe. Black
Rolf & Sales Nussbaumer

Swedish Bird Ringing Atlas (2001)
dots refer to recovery places of birds
ringed at Courish Spit, Russia (filled
square) and open dots refer to birds
ringed at Col de Bretolet, Switzerland
(open square).

countries and work has begun on them ing quarters can result in declining breed-
in a number of others. This is an impor- ing populations in areas far away. Many
tant step because it will make results from migratory birds are declining in numbers
ringing easily accessible. It will also show and detailed information about the an-
where knowledge is missing and where ef- nual movements, including important
forts in the future ringing should be fo- stop-over sites and winter quarters, is a
cused. As migration pattern change over top conservation priority.
time, particularly in relation to factors Large numbers of ringing recoveries are
such as climate change, continued bird now held in the EURING Data Bank and
ringing is important even for common they can be used to analyse more complex
species. questions about bird migration. Results of
Migration is a challenge within nature such analyses could form the basis of de-
conservation work since many populations tailed laboratory and field research into
of birds regularly move over huge areas, the navigational cues and fuelling strate-
Recoveries of Ospreys ringed in Sweden and reported during the period August-No-
and problems en route or in the winter- gies that birds use when migrating.
vember show that this species migrates on a broad front.

12 13


Adriano de Faveri
The EURING Swallow Project

A worldwide symbol of bird migration all grass are also under threat from human
across its vast geographical range and for activities and agricultural development.
different human cultures, the Barn Swal- The fascination of its journeys makes
low is also an important bio-indicator for the Barn Swallow a very popular research
habitat types which are under threat in subject among ringers. For all these rea-
different continents. sons the EURING Swallow Project (ESP)
It breeds colonially in farmlands, shar- was launched in 1997. During five years
ing this habitat with a concentration of of activities on the breeding grounds, The Swallow – a symbol of international
bird species showing worrying popula- as well as along the migratory routes co-operation.
tion declines. and on the wintering grounds, nearly
Before leaving the northern hemi- one million Swallows have been ringed
sphere for its long migrations, the Swal- by many hundred ringers in 25 differ- moult and the accumulation of fat re- fered the first confirmation based on
low stores energy reserves during a ent countries in Europe, Africa, and Asia. serves during the pre-migratory roost- field data, that the amount of fat re-
crucial roosting phase, when the birds This amazing effort has allowed the un- ing phase. At an intensively studied roost serves at departure towards Africa is
congregate at dusk in reedbeds, again a ravelling of different aspects of the life- in northern Italy it has been shown that correlated to the distance that first-year
habitat which is facing severe reduction cycle and migrations of what used to be birds can only start accumulating fat and totally un-experienced swallows
at a global scale. regarded as a very well known species. when their body moult approaches its will have to fly across ecological barri-
Roosting behaviour is also typical of The large-scale geographical coverage final stages. Optimal migration theory ers they have never seen before. Young
the winter period spent in the southern has also offered a unique opportunity also predicts that birds will reach their fi- swallows leaving southern Iberia, which
hemisphere, in vast areas of sub-Saharan to test optimal migration theories. Data nal departure conditions just before em- will cross the narrow stretch of the west-
Africa for the Western Palearctic popula- gathered in Italy could confirm a trade- barking on the crossing of possible eco- ernmost Mediterranean and the West-
tions. These areas of reeds and elephant off between the completion of body logical barriers, like the Mediterranean ern Sahara, will depart with lower fat
and Sahara for European Swallows fly- reserves than those of swallows leaving
ing to Africa. By analysing data gathered southern Italy. Those departing from It-
Hans Reinhard

from Finland southwards across Europe aly will fly a long distance over the sea
it has been possible to confirm this the- and across the widest part of the Sahara
ory. Swallows leave Finland still with re- desert, and are in fact much fatter.
duced fat stores, which are quite larger The huge number of Swallows ringed
already in birds analysed in Switzerland. during the project has also produced
Still across Italy and Spain, the amount a large number of recoveries and de-
of fat reserves in birds in the north of scribed yet unknown wintering quar-
these countries is significantly lower than ters for different geographical Euro-
that of swallows leaving the southern- pean populations. This has also led to
most latitudes. increased action for Swallow conserva-
One million Swal-
Even though it had long been thought tion in Africa, where huge numbers of
lows ringed in 25
that an aerial feeder like the Swallow birds were and still are killed for food
different coun-
would not need to store fat before mi- in Nigeria, Central African Republic, and
tries have shown
gration, but rather adopt a “fly and for- Congo.
the potential of
age” strategy, the project has shown that Thanks also to the EURING Swallow
large-scale EURING
the amount of fat accumulation in Eu- Project, the Swallow is now, more than
projects as a basis
ropean Swallows matches that of other ever before, a global symbol not only of
for scientifically
long-distance songbird migrants. bird migration but also of the need for
sound internation-
The network of EURING Swallow internationally based conservation ef-
al conservation
Project roost ringing sites has also of- forts and strategies.
policies.

14 15


Matthias Kestenholz
Bird Ringing as a monitoring technique
Great Tits easily
accept to breed in
In 2001, EU countries committed them- in population size is the result of a long
nest-boxes which
selves to halt biodiversity decline by 2010, list of demographic events: reproduc-
renders them ac-
and to evaluate this target. Beyond le- tion, juvenile survival, dispersal, recruit-
cessible for ring-
gal obligation, monitoring – the study of ment (new individuals entering the pop-
ing. Hundreds of
variation in space and time of bird population), adult survival, etc. Most of them
thousands have
ulations – is a tool for acquiring knowl- can be monitored efficiently through
been ringed for
edge on which good conservation prac- ringing. Hence, an appropriate monitor- long-term popula-
tice may be based. Monitoring is also the ing system using ringing may be able to tion studies that
main source of information to alert the determine which of productivity or sur- provided funda-
general public on the status of biodiversity vival drives population changes, whether mental insights
and thus contributes to conservation by population are regulated and thus more into evolutionary
affecting policy and behaviour. prone to be resilient to global changes, processes, popula-
The general aim of monitoring is to doc- etc. Moreover, long-term time series al- tion dynamics,
ument changes in numbers. For most bird low correlation of demographic rate vari- breeding biology
species, direct counting is far more cost ef- ation with climatic fluctuation. Combined and behavioural
fective than ringing to achieve this aim. with other methods of bird monitoring, ecology.
But counts alone are inefficient for de- monitoring by ringing allows prediction
termining mechanisms and for inferring of the fate of a bird population facing cli-
causes. From one year to another, change mate changes. Monitoring through ringing may either tor changes, through time, of key demo-
rely on intensive co-ordinated schemes or graphic parameters of bird population.
be the outcome of the accumulation of Among them, changes in migration route,

Emile Barbelette
long-term database. The former is best migration timing and migration proba-
illustrated by the “Constant Effort Site” bilities are the most evident. Last but nor
scheme (CES; also known as “Monitor- least, one of the few globally threatened
ing Avian Productivity and Survival” in bird species for which Europe has the main
North America, an acronym that speaks responsibility, the Aquatic Warbler, is al-
for itself). Initiated in 1983 in the UK and most entirely monitored through ringing,
Ireland, CES is currently organised in 16 allowing us to determine the stability of
EU countries, on 600 sites where over the stopping-over network from Western
100,000 birds are caught annually. CES is Russia and Poland to Spain.
unique in producing annual indices of re- The most useful monitoring schemes
productive success of more than 30 spe- are those that cover a large scale and that
cies throughout Europe. CES data have, may be run in the long term. Although
for example , shown that hot weather in CES is showing the way, there is consider-
spring was negatively affecting productiv- able room for improving the efficiency of
ity of already declining species. This sug- monitoring by ringing. Another direction
gests a link between climate warming and of improvement is the continuous inte-
long term population trend through re- gration of different monitoring schemes.
productive success for a large number of This means more organisation and sup-
species. The production of annual indices port for the volunteers who make up the
of productivity at a European scale is un- only network able to monitor biodiversity
der study and is likely to be achievable throughout Europe. This is achievable by
in the near future. The long term ring- encouraging scientists to work in close as-
Ringing data can be used to determine survival rates of long-lived seabirds such as
ing database is also most useful to moni- sociation with ringing schemes.
the Common Tern.

16 17


Ringing birds to understand population dynamics

Understanding the mechanisms under- fragments of the life of a ringed bird are resources during the non-breeding pe- breed for the first time and how many
pinning population growth and decline known, and statistical methods have to riod. For example, annual survival rates there are. These questions can be studied
is central for conservation and many ec- be developed to deal with this problem. of White Storks are significantly lower if nestlings are marked and if it is noted
ological and evolutionary questions. The Technical meetings regularly organised in years with droughts in the Sahel. Be- in which year they reproduce. Research-
variation of the size of a population from by EURING deal mainly with this chal- cause White Storks from most European ers from France have studied recruitment
one year to another is determined by the lenge, and they have helped considera- populations spend the non-breeding pe- in Flamingos in the Camargue. The first
number of individuals that have survived, bly to advance statistical methods. Now- riod at least partially in the Sahel, the individuals started to breed at the age
were recruited, have immigrated or em- adays, sophisticated computer programs sensitivity to droughts can explain why of 3 years, but there were also individu-
igrated. Estimates of survival, recruit- exist with which demographic rates can population changes across large areas in als that delayed their first breeding up to
ment, immigration and emigration rates be estimated from capture-recapture the European breeding area are synchro- an age of 9 years. Recruitment was higher
can be obtained, if the fate of individuals data or from data from dead recoveries. nous. Moreover, this example highlights in years following a severe winter with
can be followed through time and space. Here we highlight three different studies that successful conservation needs to in- higher mortality, showing that the effects
Birds that are ringed can be recognized showing the potential of data, gathered tegrate the complete life cycle of the spe- of strong winters are offset by earlier re-
individually allowing to estimate demo- from ringed birds, to understand popu- cies under question, not only the breed- cruitment, which reduces the impact of
graphic rates. lation dynamics. ing period. hard winter on population dynamics.
However, the estimation of demo- There are many studies about survival Recruitment, the establishment of lo- In order to understand population
graphic rates is complicated by the fact rates in birds obtained from either cap- cally hatched individuals in the popula- dynamics, it is vital to be able to assess
that marked individuals cannot always ture-recapture data or from recoveries of tion, is important for the maintenance of how much variation in survival, repro-
be observed. Some individuals may be dead individuals. Several of them have a population. To understand the impact duction or dispersal contribute to popu-
hidden at the time when the researcher shown that survival rates of migratory of recruitment on population dynamics it lation change. Surviving adults of Willow
wants to check them. Consequently, only birds depend on the availability of food must be known at which age young birds Tits contributed 64 % to the growth rate
of a Finish population, whereas the con-
tribution due to immigration (22 %) and

Jean-Lou Zimmermann

Tero Niemi
due to local recruitment (14 %) were sig-
nificantly lower. The contribution of sur-
viving adults was constant across time,
but highly variable for local recruits
and immigrants. Thus, the dynamics of
this willow tit population were mainly
due to variation in recruitment and im-
migration. However, because surviving
adults contribute so much to population
growth, any slight decline in adult sur-
vival rate has a very strong effect on the
population.
All these insights were only possible,
because birds have been ringed. With-
out individual recognition of birds in a
population, it is hardly possible to un-
derstand demographic reasons for pop-
ulation changes. Bird ringing is therefore
the basic field method to study popula-
tion declines and increases.
Greater Flamingos, the 3rd individual to the right wearing a colour ring. Willow Tit

18 19


Johann Hegelbach
Bird ringing in evolutionary and behavioural studies

When competition between species of Individual identification is particularly
Darwin‘s finches in the Galápagos archi- straightforward in birds through the use
pelago is magnified during periods of of a combination of metal and coloured
drought, Medium Ground Finches with rings. To no small extent, the widespread
smaller beaks have less overlap in their ringing of birds is the main reason why
food spectrum with the much bigger birds are the best studied vertebrates in
Large Ground Finch than their bigger evolutionary biology.
conspecifics. Thus, those Medium Ground Mating patterns are one important
Finches carrying genes that cause them trait that affects evolution. If certain
to have smaller bills survive better and birds have an opportunity to mate, while
will have more descendants in the next others do not, a change of gene frequen-
generation. Consequently, the frequency cies will also occur. Thus, the study of an-
of the genes causing smaller beaks will imal behaviour underlying mate choice The Dipper. Col-
increase in this population. Evolution has decisions and other crucial behavioural our ringing has
occurred. traits is central to a better understand- shown that this
Since it is individuals, and not popula- ing of evolution in natural populations. attractive species
tions, that carry the genes, an in-depth Again, only data from individually recog- can sometimes be
understanding of evolution is rarely pos- nizable animals can help us answer some infanticidal and
sible without studying individuals. This, of these questions. Inbreeding, the mat- incestuous.
however, requires that individuals can be ing of relatives, for example, has long
recognized and followed over a period been an issue of great interest among an-
of time, ideally over their entire lifespan. imal and plant breeders. How often does inbreeding occur in the wild and what site mating patterns among individual
are its consequences? When birds of one birds from the same population.
population are individually colour-ringed Some of the most interesting behav-

Matthias Kestenholz
for many years, we can construct pedi- iours are those that appear at first to con-
grees that allow us to infer the degree of tradict simple evolutionary explanations.
inbreeding and thus its causes and con- One such behaviour is infanticide which
sequences. On a small island in Canada, has been described in a small number of
for example, Song Sparrows have been bird species including the European Dip-
The Alpine Chough shown to mate with a relative as often per. Why would male Dippers kill young
is a social bird liv-
as expected by chance. Thus, Song Spar- in nests of other pairs in the population
ing in high moun-
rows do not seem to avoid mating with when they do not seem to have anything
tain areas. Though
relatives, despite the fact that inbreed- to do with that nest? At first sight, one is
highly gregarious,
ing considerably reduces reproductive tempted to explain such occurrences as
ringing and col-
success and survival. aberrant behaviours. However, an alter-
our-ringing of this
In a population of European Dippers in native, evolutionary explanation is that
confiding species
Switzerland, one female paired up with the infanticidal males are killing the
not only provided
her son which himself had originated young so that the females will lay a new
insights into home
from a pairing between her and her clutch which could be fathered by the in-
range and popula-
brother. On the other hand, one male of fanticidal male. Observations of individ-
tion structure, but
these Cinclus c. aquaticus was resighted ually colour-ringed birds combined with
also allowed to
in Poland, mated to a dipper that had genetic analyses have the potential to
study individual
been ringed in Sweden as a C. c.cinclus. resolve this and many other fascinating
foraging strate-
It is difficult to conceive of more oppo- questions in modern biology.
gies.

20 21


Dispersal and population persistence

after Paradis et al. 1998
Most European bird populations live in portant to control for variation in record- There is now increasing evidence from
habitats that are highly fragmented as a ing effort. fieldwork and mathematical modelling
result of human activities. The dynamics Current knowledge of natal and breed- that frequencies of occurrence and densi-
and genetic diversity of populations inhab- ing dispersal is based on analyses of ring- ties of many bird species are lower within
iting such landscapes are often critically de- ing data. For most species natal dispersal is habitat fragments than in large areas of
pendent on dispersal patterns, as well as greater than breeding dispersal, and spe- continuous habitat. For example, a study
on reproduction and survival within hab- cies with higher natal dispersal also tend to in Northern Belgium found that Nuthatch
itat patches. To gain a better understand- move further between subsequent breed- densities in forest fragments were about
ing of how to manage these landscapes for ing years. Average (geometric mean) dis- half those in continuous areas of forest. In
birds we need information on dispersal de- persal distances vary greatly between spe- this species, dispersal distances are larger
rived from bird-ringing. cies. For example, in Britain and Ireland and territory vacancies are filled more
Two main types of dispersal are recog- Blackcaps have an average natal dispersal slowly in fragments than in continuous
nized in population ecology. Natal disper- distance of 17,5 km while House Sparrows habitat. Furthermore, areas where most The relationship between average natal
sal refers to movements between the place move an average of only 0,2 km between of the habitat is fragmented act as sinks, dispersal distance and population size
of birth and that of first breeding, while their natal and breeding sites. Dispersal with populations only being maintained by for 75 species. More abundant species
breeding dispersal refers to movements patterns are influenced mainly by the eco- immigration from more continuous habi- generally occupy a wider range of habi-
between subsequent breeding attempts. logical characteristics of individual species, tat. In order to manage populations within tats and need to move less far in order
There are two complementary ways of with those occupying more restricted and fragmented landscapes it is vital to under- to find potential nesting sites.
studying dispersal using bird ringing. Mark- patchy habitats showing greater dispersal. stand these relationships between popula-
recapture and mark-resighting data can be Scarcer species generally occupy more re- tion density, habitat quality and dispersal.

Alain Saunier
used to measure dispersal within local pop- stricted and patchy habitats and this results Understanding dispersal is equally impor-
ulations, or between populations occupy- in a negative relationship between disper- tant for the conservation of colonial spe-
ing a limited number of colonies or habitat sal and abundance. For similar reasons, dis- cies such as seabirds, where immigration
patches. These studies provide a high reso- persal is greater amongst birds occupying and emigration are key determinants of
lution picture of local movements but may wetland habitats. Dispersal is also greater colony size.
miss long-distance ones. In contrast, analy- in migrants than in residents, presuma- Dispersal also has important implications
ses of ring recoveries provide a broad over- bly because of the opportunities for the for the maintenance of genetic diversity
view of dispersal patterns including long- former to explore new areas. There is much within populations, and for rates of evo-
distance movements, but may lack fine scope to explore such patterns further us- lution in changing environments. In most
detail. In both of these methods it is im- ing data from the EURING databank. bird species the greater natal dispersal of
females compared to males helps to reduce
inbreeding depression. A study of colour-
marked Great Reed Warblers in Sweden
found that low genetic variation and the
occurrence of inbreeding depression were
associated with restricted dispersal and
with a lack of any dispersal difference be-
tween males and females. These genetic
studies further emphasise the importance
Natal dispersal
of improving our understanding of disper-
distances of Song
sal, which remains poor relative to that of
Thrushes meas- The Nuthatch is a good example of a
other demographic processes. Large-scale
ured using ring re- species where patch occupancy in frag-
0.1
studies of marked birds should form an im-
coveries from Brit- mented woodland habitats is influenced
portant part of this research effort.
ain and Ireland. by dispersal.

22 23

Euring Brochure 2007

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