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Discovering the migration and non-breeding areas of sand martins and house martins breeding in the Pannonian basin (central-eastern Europe)

  • University of Nyíregyháza
  • Swiss Birdradar Solutions AG
  • MME/BirdLife Hungary
  • MME/Birdlife Hungary

Abstract and Figures

The central-eastern European populations of sand martin and house martin have declined in the last decades. The drivers for this decline cannot be identified as long as the whereabouts of these long distance migrants remain unknown outside the breeding season. Ringing recoveries of sand martins from central-eastern Europe are widely scattered in the Mediterranean basin and in Africa, suggesting various migration routes and a broad non-breeding range. The European populations of house martins are assumed to be longitudinally separated across their non-breeding range and thus narrow population-specific non-breeding areas are expected. By using geolocators, we identified for the first time, the migration routes and non-breeding areas of sand martins (n = 4) and house martins (n = 5) breeding in central-eastern Europe.In autumn, the Carpathian Bend and northern parts of the Balkan Peninsula serve as important pre-migration areas for both species. All individuals crossed the Mediterranean Sea from Greece to Libya. Sand martins spent the non-breeding season in northern Cameroon and the Lake Chad Basin, within less than a 700 km radius, while house martins were widely scattered in three distinct regions in central, eastern, and southern Africa. Thus, for both species, the expected strength of migratory connectivity could not be confirmed.House martins, but not sand martins, migrated about twice as fast in spring compared to autumn. The spring migration started with a net average speed of  400 km d–1 for sand martins, and  800 km d–1 for house martins. However, both species used several stopover sites for 0.5–4 d and were stationary for nearly half of their spring migration. Arrival at breeding grounds was mainly related to departure from the last sub-Saharan non-breeding site rather than distance, route, or stopovers. We assume a strong carry-over effect on timing in spring.
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Discovering the migration and non-breeding areas of sand martins
and house martins breeding in the Pannonian basin (central-eastern
Tibor Szép, Felix Liechti, Károly Nagy, Zsolt Nagy and Steffen Hahn
T. Szép, Inst. of Environmental Science, Univ. of Nyíregyháza, Nyíregyháza, Hungary. – F. Liechti ( and S. Hahn,
Dept of Bird Migration, Swiss Ornithological Inst., Sempach, Switzerland. – K. Nagy and Z. Nagy, MME/BirdLife, Budapest, Hungary.
e central-eastern European populations of sand martin and house martin have declined in the last decades. e driv-
ers for this decline cannot be identified as long as the whereabouts of these long distance migrants remain unknown
outside the breeding season. Ringing recoveries of sand martins from central-eastern Europe are widely scattered in the
Mediterranean basin and in Africa, suggesting various migration routes and a broad non-breeding range. e European
populations of house martins are assumed to be longitudinally separated across their non-breeding range and thus
narrow population-specific non-breeding areas are expected. By using geolocators, we identified for the first time, the
migration routes and non-breeding areas of sand martins (n 4) and house martins (n 5) breeding in central-eastern
In autumn, the Carpathian Bend and northern parts of the Balkan Peninsula serve as important pre-migration areas for
both species. All individuals crossed the Mediterranean Sea from Greece to Libya. Sand martins spent the non-breeding
season in northern Cameroon and the Lake Chad Basin, within less than a 700 km radius, while house martins were widely
scattered in three distinct regions in central, eastern, and southern Africa. us, for both species, the expected strength of
migratory connectivity could not be confirmed.
House martins, but not sand martins, migrated about twice as fast in spring compared to autumn. e spring migra-
tion started with a net average speed of 400 km d–1 for sand martins, and 800 km d–1 for house martins. However,
both species used several stopover sites for 0.5–4 d and were stationary for nearly half of their spring migration. Arrival at
breeding grounds was mainly related to departure from the last sub-Saharan non-breeding site rather than distance, route,
or stopovers. We assume a strong carry-over effect on timing in spring.
Various populations of long distance migratory birds in the
western Palearctic have declined in recent decades (Sander-
son et al. 2006). Candidate factors are climate change (Both
et al. 2006), changes of habitats in breeding (Donald et al.
2001), migration, and non-breeding areas (Zwarts et al.
2009, Maggini and Bairlein 2011). To identify carry-over
effects and seasonal interactions on population development
(Harrison et al. 2011) we need comprehensive knowledge
about the whereabouts of individuals during the entire
annual cycle. In contrast to detailed information available
for breeding periods, we are still lacking information for
migration and non-breeding periods (Vickery et al. 2014),
especially for long distance passerine species.
In the Pannonian basin (central-eastern Europe), 58% out
of 26 common long distance migrant species have declined
significantly since 1999, whereas only 8% show positive
trends (Szép et al. 2012). e information deficiency in rela-
tion to the migration and non-breeding areas of these popu-
lations are immense, especially as they often play key roles on
the dynamics of the entire European populations (BirdLife
2004). e sand martin Riparia riparia and house martin
Delichon urbicum are typical examples: their populations
suffered from strong declines with mean annual population
growth rates of –2.7% in sand martins (during 1986–2014,
Szép unpubl.) and –4.7% in house martins (1999–2014,
Szép et al. 2012). Information on their distribution during
the non-breeding period is almost entirely lacking.
e sand martins breeding in eastern Hungary were
found among the first where adverse climate conditions in
potential African non-breeding areas (Sahel) could be cor-
related with the decreasing annual survival rates (Szép 1995).
Despite the huge effort on ringing with almost 140 000 indi-
viduals in eastern Hungary during more than 30 yr, there
is no recovery in Africa for this breeding population. For
other Hungarian and the neighbouring Czech and Slovakian
© 2016 e Authors. is is an Online Open article
Guest Editor: Anders Hedenström. Editor-in-Chief: Jan-Åke Nilsson. Accepted 15 November 2016
Journal of Avian Biology 48: 114–122, 2017
doi: 10.1111/jav.01339
is is an open access article under the terms of the Creative
Commons Attribution License, which permits use, distribution
and reproduction in any medium, provided the original work is
properly cited.
populations, there are only eight recoveries from the African
continent, Lake Chad (2), Morocco, east of Tunisia (4), DR
Congo and two nearby recoveries from Israel and Lebanon
in spring (Heneberg 2008, Szép 2009). us, sand martins
are assumed to migrate on a broad front (Turner and Rose
1989), and should be widely distributed in sub-Saharan
Africa, eastern and southern Africa (Walther et al. 2010).
e house martin is one of the ten most common Palae-
arctic African migrants (Hahn et al 2009) but spatial infor-
mation during the non-breeding season is very scant (Hill
1997). For birds breeding in Germany there are just six
recoveries from the African non-breeding areas spanning
the Central African Republic, Cameroon, DR Congo, and
Zambia (Bairlein et al. 2014). Moreover for the large popu-
lation in the UK, there is only a single recovery from Nigeria
(Hill 2002). House martins breeding in northern Europe
had been recovered in southern Africa (Hill 2002, Valkama
2014), whereas the little available information for birds from
central-eastern Europe points to migration routes across the
Balkan peninsula, southern Italy and north-western Libya
during autumn, and north-western Algeria, Malta, and the
Balkans during spring (Cepák 2008, Králl and Karcza 2009).
Albeit small, this tantalising information raises the sugges-
tion that European house martins might be longitudinally
separated in Africa with eastern populations overwintering
in east Africa, central populations in Zambia, Zimbabwe
and South Africa, and western populations distributed in the
region of the Bight of Benin (Hill 2002).
In this paper we investigate the migration and non-breed-
ing areas of sand martins and house martins breeding in the
Pannonian basin using geolocators, and compare our results
with the ringing recoveries of the two species during the
non-breeding season. Finally, we also study the diurnal and
nocturnal use of cavities during the non-breeding season to
explain the very low numbers of African recoveries especially
for house martins.
Studied populations
e sand martin population we studied breeds along the
river Tisza in eastern Hungary and has been intensively
monitored since 1986 (Szép et al. 2003b). e house mar-
tin colonies we studied are situated in two villages along the
upper section of the river Tisza, where 40–280 birds have
been ringed annually since 2010.
Deployment of geolocators
In 2012, we equipped adult breeders of both species with
SOI GDL2 ver. 1.2 (Swiss Ornithological Inst., Sempach,
Switzerland) geolocators using a modified leg-loop harness
(Supplementary material Appendix 1). Including the har-
ness, these geolocators weigh 0.6 g.
Sand martins were captured at the end of the breeding
season, between 9–25 July 2012, in two colonies along the
river Tisza, at Szabolcs (48.188°N, 21.488°E, 35 males, 34
females, colony size 1700 pairs), and at Gávavencsellő
(48.199°N, 21.588°E, five males, six females, colony
size 100 pairs). Average body mass of the geolocator-har-
nessed birds at deployment was 13.4 g (SD 0.80, n 80);
thus geolocators mass was 4.5% of body mass.
We recaptured five sand martins in May–June of 2013
(two females and one male at Szabolcs and two females
at Gávavencsellő), and received geolocator data from four
birds (one geolocator failed). Additionally, another female
with a geolocator was identified at Szabolcs using a digital
camera, but was not recaptured. All recaptured birds were
active breeders. e return rate of geolocator-harnessed birds
varied between Szabolcs (5.8%) and Gávavencsellő (18.2%),
but not significantly (Fisher’s exact test, p 0.19). Return
rates of geolocator-harnessed birds and controls (caught at
the same catching events in 2012) showed significant dif-
ference at Szabolcs (control: 17.8%, n 129, geolocators:
5.8%, n 69 birds, Fisher’s exact test, p 0.028), but not
at Gávavencsellő (control: 21.7%, n 46, geolocators:
18.2%, n 11, Fisher’s exact test, p 1.0). e return rate
of females was double that of males, but the difference was
not significant (female: 4/40, male: 2/40, Fisher’s exact test,
p 0.67).
House martins were equipped with geolocators at
Nagyhalász-Homoktanya (48.076°N, 21.752°E 21 males,
18 females and 1 adult of unknown sex) and at Tiszabercel
(48.158°N, 21.643°E three males and seven females between
19 July and 3 August 2012). e mean body mass of geolo-
cator-harnessed birds was 17.1 g (SD 1.04, n 50), while
the geolocator mass was 3.5% of adult body mass. e colony
at Nagyhalász-Homoktanya comprised 317 nests (41% with
clutches), whereas at Tiszabercel the colony consisted of
43 nests (51% with clutches).
Five geolocator-harnessed birds were recaptured at
the colony of Nagyhalász-Homoktanya (three males, two
females) in July of 2013. e return rate (12.5%) was lower
than 38.9% return rate of control birds (n 18) (Fisher’s
exact test, p 0.035). At Tiszabercel neither geolocator nor
control birds were recaptured.
Light-level data analysis
We calculated positions using the R-package GeoLight (Lis-
ovski and Hahn 2012). However, we could not use light
data from breeding ranges to calibrate sun elevation angles
because of the non-natural sunset and sunrise that the birds
experienced inside cavities where they nest. We therefore
used median sun elevation angle (–2.7°) for all individu-
als of both species derived by the Hill–Ekstrom calibration
method (Lisovski and Hahn 2012) from long non-breeding
stationary periods ( 50 d). is sun elevation angle was
very close to the one measured with the same geolocator type
in another study (–2.8) that looked at more than 100 barn
swallows (Liechti et al. 2014).
Data filtering
Light level was recorded every five minutes and varied
between 0 (total darkness) and 63 (maximum value; for sen-
sor specific details see Adamík et al. 2016). Based on these
values, we defined three time periods per day: 1) a sunrise
period that lasted from the first light value 0 after at least
four hours of zero values until the light value reached the
maximum (63) level; 2) a sunset period that lasted from the
last maximum light level until the last value above zero, fol-
lowed by at least four hours of zero values; 3) a lightness
period that lasted from the end of the sunrise period until
the start of the sunset period.
Both species breeds in dark burrows or half-cup nests and,
occasionally, they use similar sites (e.g. holes, caves) outside
the breeding season. is behaviour can be used to divide
recorded sun events (sunrise and sunset) into two classes:
natural and non-natural (Liechti et al. 2014, Gow et al.
2015). To filter such potentially biased light data, we defined
non-natural sunrises and sunsets on the basis of whether or
not the first/last light value was below or above an empiri-
cally derived threshold. When the level of first/last light
value was less than 5 (84.5% of 5313 cases), the minimum
length of sunrise/sunset varied between 10–20 min; in other
cases (first/last light value 5, 15.5%) the minimum
length of these periods varied between 0–20 min. In the first
case, we considered the sunrise or sunset as natural, while in
the second as non-natural. Zero light values during sunrise/
sunset could also indicate the use of dark sites during the
entire sunrise/sunset period. Such events were significantly
more frequent when the first/last light value was 5 or higher
(30.2% of 775 cases) than for lower values (6.6% of 4537
cases; c21 405.64, p 0.001). Consequently, sunset and
sunrise periods with a zero value were also defined as unnatu-
ral. Finally, differences in shading between consecutive sun
events (sunrise and sunset) can cause an asymmetry in day
and night length and lead to error in the calculation of noon
and midnight, thus longitude. We therefore calculated the
difference in the length of consecutive sun event periods and
for further analyses, days and nights with differences larger
than 55 min (upper 5% quartile) were excluded, as well as all
non-natural sun events (example in Supplementary material
Appendix 1, Fig. A1).
Defining stationary periods
Geolocation divides the temporal pattern of observations
into two time steps per 24 h (daytime and night-time), and
we assumed that considerable shifts in consecutive sunrises
or sunsets indicate a movement. Generally, stationary peri-
ods were defined based on the time shifts between two con-
secutive, equal sun-events (sunrises or sunsets, respectively),
which include the two time steps (daytime and night-time).
We decided not to use the changepoint algorithm imple-
mented in the GeoLight-software, instead applied some
simple rules easy to follow. Our light data had a low impact
of shading (except cavity-use), thus, from visual inspection
alone it was obvious that some of the very short stopover
periods (1–3 d) were missed by the standard algorithm. By
using the same data as the standard algorithm we therefore
developed a few arbitrary but objective rules to define sta-
tionary periods. ere were almost no differences in sta-
tionary periods longer than 7 d, but we could identify in
addition some short stopovers during migration. We believe
that this pragmatic approach facilitated the opportunity to
derive more detailed results than with a standard approach
in our dataset. We determined for each time step whether it
was a stationary or movement period by applying the fol-
lowing rules when all sun events were natural: 1) if the time
shift between two equal and consecutive sun-events was less,
or equal to five minutes, the second time period (daytime
or night-time) was classified as a stationary period; 2) if a
time shift was more than five minutes between two equal
sun-events but smaller than between the two sun-events in
the step before, we assume that the bird was stationary dur-
ing the second time period (daytime or night-time); 3) if a
time shift was more than five minutes between two equal
sun-events, and larger than between the two sun-events in
the step before, we supposed that the bird was moving dur-
ing the second time period (daytime or night-time); 4) if
condition 2 was true, but the difference in the duration of
the actual day (or night, respectively) and the day before (or
night, respectively) was larger than 10 min, then the period
was classified as an uncertain stationary period.
ese rules are arbitrary and specifically adapted to the
data we collected with this type of geolocator. Neverthe-
less, our classification is based on objective rules and, most
importantly, is independent of calculated positions. us, all
geographical positions within a stationary period (not inter-
rupted by a movement period) were pooled to a single site,
and if median geographic position between consecutive sites
was within a 200 km radius, then sites were pooled. Sites
were defined by their median and 90% quartile of all geo-
graphical positions within this time period.
e seasonal pattern was defined by four specific station-
ary periods: 1) the end of the breeding period was defined
by departure from the breeding grounds (leaving the first
stationary site within 200 km from the breeding grounds);
2) arrival at the first, and departure from the last site north
of the Mediterranean Sea defined the pre-migratory period;
3) arrival at the first and departure from the last site south
of the Sahara ( 23.5°N) defined the non-breeding resi-
dence period; 4) arrival at breeding grounds was defined by
a stationary period within 200 km or by the occurrence of
frequent unnatural sun events due to nest cavity visits. e
initiation and end of autumn migration was defined by the
end of the pre-migratory period and the start of the non-
breeding residency. Spring migration was defined by the end
of the non-breeding residency and the start of the breed-
ing period. e area associated with the longest stationary
period south of the Sahara ( 23.5°N) was defined as the
main residence area during the non-breeding period.
We defined the time period of autumn migration as
the last date of the last stationary site ( 5 d) north of
the Mediterranean Sea, and the first date of the first sta-
tionary site ( 5 d) south of the Sahara desert (latitude
23.5°N). e period of spring migration was defined
vice versa.
Use of cavities
Sand martins and house martins are diurnal foragers of aer-
ial plankton and use cavities for breeding as well as perhaps
for resting (Cramp 1988). We quantified the use of cavi-
ties within the annual cycle and identified days with cavity
visits during daylight when periods of light records of zero
occurred for at least five minutes. Cavity use during nights
was determined if either sunrise or sunset was defined as
unnatural events. In the case of one bird (S4, sand martin)
the geolocator had slipped to the side, thus data could not be
southern Africa (distance 8050 km) (Fig. 1C). ree of the
five birds we tracked stayed in one area for an average of 159
d (range: 144–177 d, Supplementary material Appendix 1,
Table A1), while two birds (H3, H4) used two separated sites
(400 km, 1200 km) (Fig. 1C). Between March and May, all
the tracked birds moved to other sites, an average of 1350
km (range: 750–2050 km) from their main non-breeding
residences (Supplementary material Appendix 1, Table A1,
Fig. 1C). Surprisingly, only three of the five individuals we
tracked moved northwards to sites closer to the southern
Saharan border while two birds moved to sites in the west/
southwest and stayed there for at least three weeks before
departing for their spring migration.
Spring migration
ree sand martins migrated straight to the north across the
desert, while one bird followed a westerly loop (Fig. 1B).
Sand martins departed between 11 April and 7 May, and
used 5–6 stopover sites with an average stopover duration of
1.5 d (0.5–4 d) (Fig. 2B, Supplementary material Appendix 1,
Table A1). Arrival at the breeding colonies was between 29
April and 24 May resulting in a migration duration of 14 d
(range: 8–17 d) (Fig. 2B). eir overall migration speed was
an average of 349 km d–1 (range: 241–498 km d–1), while
their net migration speed, excluding times spent at stopover
sites (mean: 6 d, range: 6–11 d), was 621 km d–1 (range: 424–
822 km d–1, Supplementary material Appendix 1, Table A1).
In contrast, house martins used two distinct migration
routes related to difference in their main non-breeding sites.
Birds from eastern Africa moved along an eastward loop
across the Arabian Peninsula, Turkey, and the Balkan Penin-
sula and thus avoiding the crossing of the Mediterranean sea
(Fig. 1D), while individuals overwintering in central Africa
and South Africa moved straight across the desert and then
crossed the central part of the Mediterranean sea through
Malta/Sicily, southern Italy and Adriatic Sea, a very similar
flyway to two of the tracked sand martins. Individuals over-
wintering in central and eastern Africa departed between 26
April and 8 May (Fig. 2D), and stopped over at 3–7 sites for
an average of one day (0.5–4 d). ey arrived at the breeding
sites between 5 and 18 May, after 10 d (6–16 d) on migration
(Fig. 2D, Supplementary material Appendix 1, Table A1).
e bird overwintering in southern Africa left this site at the
end of March and moved northwards to central Africa using
three stationary sites (2–6.5 d). From these sites onwards,
their migration was very similar to others (Fig. 2D); average
overall migration speed was 594 km d–1 (range: 360–887 km
d–1), and net migration speed, excluding time spent at stop-
over sites (mean: 4 d, range: 2–9 d), was 1081 km d–1 (range:
615–1462 km d–1, Supplementary material Appendix 1,
Table A1). In both species, individuals with the southernmost
main non-breeding sites left sub-Saharan Africa earlier and
were first to arrive at the breeding grounds.
Usage of cavities during the annual cycle
e majority of birds of both species used cavities during the
day when breeding but only occasionally during migration and
the non-breeding residence period (Fig. 3A). Cavity use during
the nights occured most frequently during the breeding period
used for defining cavity usage (one third of positioning data
was influenced).
Data available from Movebank Data Repository: < doi:
10.5441/001/1.214298181 > (Szép et al. 2016).
Autumnal pre-migration period
Sand martins departed from their breeding sites before
August (Szép unpubl.), although exact departure dates were
not recorded because the logging season started 1 August.
In August, all tracked birds were roaming in the Carpathian
Bend or in Serbia, Romania, and Bulgaria until departing for
their southbound migration (Fig. 1A, Supplementary mate-
rial Appendix 1, Table A1).
Tracked house martins departed between the end of July
(K. Nagy unpubl.) and the first half of August from their
breeding site to the Carpathian Bend (three individuals) as
well as to western Ukraine and western parts of Romania.
(Fig. 1C, Supplementary material Appendix 1, Table A2).
Autumn migration
e autumn migration coincided with the equinox period,
and thus latitudinal estimates are not available during this
period. However, longitudinal data indicated migratory
tracks across the Balkan region with subsequent traverses of
the Mediterranean Sea in both species (Fig. 1A, C). Sand
martins showed a clear shift in longitude, with an easterly
shift in the first half of the migration period and westerly in
the second. e sand martins departed on average at 9 Sep-
tember (5–14 of September) and arrived after 17 d (16–20
d) at the non-breeding areas (mean: 26 September, range:
23–30 September) (Fig. 2A). e overall migration speed
averaged at 229 km d–1 (range: 155–271 km d–1).
Based on longitudinal positions house martins followed a
more or less straight route to the non-breeding area in sub-
Saharan Africa (Fig. 1C). ey departed on average also at 8
September (5–12 September) and arrived after 24 d (21–30)
at the non-breeding area (mean: 3 October, range: 2–5 Octo-
ber) south of the Sahara (Fig. 2C). e overall migration
speed averaged at 193 km d–1 (range: 176–219 km d–1).
Non-breeding residence
e main non-breeding areas of tracked sand martins were
situated in the Lake Chad Basin (Fig. 1A), and thus, on aver-
age 4250 km (3850–4600 km) separated from the breeding
sites (great circle distance). ree of four birds used a single
non-breeding site for on average 170 d (range: 151–193 d),
and one bird (S2) used three distant areas (400 km, 750
km, Fig. 1A). Before spring migration, between March and
May, two individuals moved to pre-migratory sites near Lake
Chad for about 12–39 d (Fig. 1A).
House martins were distributed widely across sub-
Saharan Africa; we tracked two individuals in central Africa
(4250 and 4500 km great circle distances from their breeding
sites), two individuals in eastern Africa (Uganda, Ethiopia,
distances of 4250 and 5200 km), and one individual in
is study has revealed, for the first time, the spatio-tempo-
ral migration patterns and non-breeding locations for indi-
vidual sand martins and house martins.
and less often during non-breeding residence and migration
periods (Fig. 3B). Results show that house martins used cavi-
ties more often on their African non-breeding (15.3 vs 0.7%,
c21 95.129, p 0.001) and breeding sites (80.3 vs 50.4%,
c21 36.219, p 0.001) than sand martins (Fig. 3B).
Figure 1. Individual tracks of sand martins (A, B) and house martins (C, D) from breeding areas in the Pannonian basin to the nonbreeding
areas in Africa (A, C) and back (B, D). Each colour represents an individual track. Subsequent stationary periods of an individual are con-
nected by dashed lines, except for the autumn migration period during equinox times. e connecting lines are interpretations due to
longitudinal information alone. Stationary periods are labelled by a digit (individual 1–5), a character (time period a autumn, w winter,
s spring) and second digit (sequence of individual time period). Stationary sites with more than 20 positions were marked by the median
and the 90% range of the positions, for shorter stopover periods (with circles) the median and an arbitrary standard error of 200 km for
longitude, and 300 km for latitude are indicated. For sand martins all distant captures/recaptures from the studied population are indi-
cated in panel (A) (autumn , 1 August to 11 September) and panel (B) (spring , 8 April to 24 May). For further details see Supplemen-
tary material Appendix 1, Table A1.
but not fully with the 38 spring recapture/recoveries from
our studied population, which are distributed along the
wide west–east range of the Mediterranean basin (Fig. 1B).
While recoveries do point towards a more widespread non-
breeding range in Africa with low migratory connectivity,
our results support the opposite view. Due to considerable
differences in reporting rates among the different countries,
ringing recoveries/recaptures have a considerable geographi-
cal bias. However, our small sample size does not allow for
a final conclusion with respect to the strength of migratory
connectivity. Obviously, the main non-breeding area of our
studied population is situated more to the east compared to
recoveries of the western and central European populations
(Mead 2002, Walther et al. 2010, Bairlein et al. 2014). Trace
element profiles of feathers grown by the British and Span-
ish martins while in Africa (overwintering in the western
Sahel) differed from Hungarian birds (Szép et al. 2003a) in
concordance with the geolocation result.
In contrast, the house martins in our study are shown to
occupy a much larger non-breeding range than sand martins.
We identified three distant, non-breeding areas in central,
eastern, and southern Africa that appear to have weak migra-
tory connectivity. Very few central European birds have been
recovered from central Africa (Bairlein et al. 2014), and
records of non-breeding areas in eastern Africa represent
e Carpathian Bend is well known as an important
area for the preparation of autumn migration in both spe-
cies (Králl and Karcza 2009, Szép 2009), but our study now
shows that some northern parts of the Balkan Peninsula are
similar important. Recapture data from birds from our stud-
ied populations confirm this finding (Fig. 1A).
When migrating, our track records show that sand mar-
tins move along the Balkan Peninsula, and cross the Mediter-
ranean Sea at Greece in a narrow band, in contrast to recent
recoveries from Italy and Malta that indicate a much wider
autumn migration corridor (Cepák 2008, Heneberg 2008,
Králl and Karcza 2009, Szép 2009). Mismatch between our
records and others may be due to the specific weather con-
ditions during the study year, as all individuals we studied
departed for their autumn migration within a very narrow
nine day time period. In addition, individuals from both
species followed a route which included just a 500 km sea
crossing. However, due to a lack of latitudinal information,
we cannot distinguish whether, or not, this directional shift
occurred in northern Africa (Fig. 1A).
Contrary to our expectations, the studied sand martins
spent the non-breeding season in an area with a radius of
less than 700 km in northern Cameroon and the Lake Chad
Basin. is result is consistent with two central-eastern Euro-
pean population ringed birds recovered from Lake Chad,
02000 4000 6000
Distance from the breeding area (km)
Distance to the breeding area (km)
02000 4000 6000
Distance from the breeding area (km)
–6000–4000 –2000 0
–6000 –4000 –2000 0
Distance to the breeding area (km)
Figure 2. Individual timing of migration and distances covered for the sand martins (A, B) and the house martins (C, D) in autumn (A, C)
and spring (B, D). Distances (km) are given in relation to the breeding sites. Dots refer to arrival and departure at the specific site indicated
in the legends (cf. Fig. 1).
behaviour could be estimated. e most striking difference
in migratory routes was not between species, but rather
between geographical positions of main non-breeding areas.
Identified passage areas in the spring across the central part
of the Mediterranean basin coincide very well with most
recapture sites known for both Pannonian populations
(Cepák 2008, Heneberg 2008, Králl and Karcza 2009, Szép
2009). Only two house martins overwintering in eastern
Africa circumvented the Mediterranean Sea on their spring
migration as is the case in other insectivorous birds (i.e.
red-backed shrikes; Tottrup et al. 2012). Although autumn
migration routes can only be reconstructed here using lon-
gitudinal information, there is good evidence that none of
the individuals followed the same route in both autumn and
spring. Migration duration in sand martins was very simi-
lar in autumn and spring, while house martins spent almost
three times more days on their autumn compared to their
spring migration. As a result, the overall travelling speed of
house martins was about 16% lower than the sand martins
in autumn, but 70% faster in the spring. Indeed, five out
of the nine birds we tracked returned in spring in 10 d or
less. Departure and arrival dates were also less synchronous
in the spring compared to the autumn for all individuals of
both species, but there was a high correlation in departure
and arrival dates (r 0.88, Pearson) with the exception
of the house martins in autumn. In both seasons, migratory
distances were slightly longer for house martins than they
were for sand martins ( 20%), taking into account the first
(for autumn) and the last (for spring) sub-Saharan stationary
sites. ere were also no obvious differences in overall migra-
tion speeds in the spring within species compared to dates,
distances, or chosen route. us, in both species, arrival at
breeding grounds was strongly determined by the date of
departure from the last sub-Saharan non-breeding site.
During spring migration, when time spent at stopover-
sites could be estimated, individuals of both species where
stationary for nearly half of their migration period. Net
migration speeds were over 400 km d–1 for sand martins,
rising to twice this value for house martins, over 800 km
d–1; this strongly suggests that these birds use tail winds, as
air speeds measured for migrating sand martins and house
martins average around 40 km h–1 (Liechti and Bruderer
2002). In contrast, net migration speeds during the spring
tended to be higher for individuals using more distant non-
breeding residence areas; these birds must have either been
able to accumulate more fuel reserves before departure, prof-
ited from abundant food resources en route, or benefited
more from tail winds. As none of the individuals (in both
species) surpassed another during spring migration, and
because spring migration was generally fast (especially in
house martins), we assume that there is a strong carry-over
effect between departure from sub-Saharan Africa and arrival
at breeding grounds although more track records will clearly
be needed to statistically support this assumption.
To define stationary periods during spring migration
in such details, we had to overcome the standard method
used so far (GeoLight). We must admit that our approach
provided reliable results only because of the high quality
light data, with very minor shading effects (Lisovski et al.
2012). Based on our data, the fastest spring migration of
a house martin (H5) was reconstructed using a movement
new results for central-eastern European breeding house
martins. Non-breeding areas in southern Africa were already
known for northern European and German populations
(Hill 2002, Bairlein et al. 2014, Valkama 2014), but had
not been recorded before for central-eastern European popu-
lations. All the non-breeding sites for Pannonian birds are
situated east with respect to indirectly assigned non-breeding
areas for a Dutch population (Hobson et al. 2012) and some
north Italian individuals (Ambrosini et al. 2011). Neverthe-
less, there is considerable overlap in the non-breeding areas
now known for Pannonian house martins with several other
European populations; as a result, our findings do not sup-
port the hypothesis that there is a longitudinal separation in
the non-breeding areas of European populations (Hill 2002,
Ambrosini et al. 2011). Within the pre-migratory period,
two of our five house martins moved considerably westward,
towards an area where birds from the western and central
European population have also been recovered during this
time of the year (Bairlein et al. 2014). However, whether
or not these birds spent their whole non-breeding period
within this area remains unclear.
One reason for the low recovery rate of house martins
compared to other swallows might be their more frequent
use of cavities (e.g. caves, trees, buildings) during the non-
breeding season in Africa. Such roosts are much more diffi-
cult to find, are occupied by a smaller number of individuals,
and therefore are less attractive to local people than the huge
roosts of the other two swallow species (Hill 2002).
Spring migrations of our studied individuals took
place after the equinox and, therefore, tracks and stopover
Frequency of usage of cavities
during day(%)
House martin Sand martin
Frequency of usage of cavities
during nights(%)
House martin Sand martin
Figure 3. Frequency of cavities usage (mean SD) of sand martins
and house martins during the day (A) and the night (B) for the four
non-breeding periods defined (see Methods) and the breeding sea-
son (significant differences are marked with ***: p 0.001).
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for the whereabouts of the Pannonian populations of sand
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geolocation remains the only method to track the martins
to date.
Acknowledgements – We thank Ákos Pelenczei, Zoltán Görögh,
János Danku, Annamária Danku, Beáta Bokor, Ivett Kakszi, Zsolt
Hörcsik, the members of the local chapter of the MME/BirdLife
Hungary for the important help in the field work, and Edit Molnár
for processing our field data. e deployment of the geolocators
and related field works were carried out with the permission of the
Hungarian National Inspectorate for Environment, Nature and
Water (14/2104/5/2012). e study was donated by ‘Madárvé-
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Supplementary material (Appendix JAV-01339 at < www. >). Appendix 1.
... However, more specific information about migration routes are largely lacking and records of nonbreeding sites are mainly limited to the Senegal river delta [23]. The only available tracking data come from a Hungarian population, which migrates along the eastern Afro-Palearctic migratory flyway to the lake Chad region [24]. Ring recoveries from southern Europe and Africa further suggest a migratory divide with eastern breeding population migrating along the eastern Afro-Palearctic flyway and western populations along the western Afro-Palearctic flyway [23]. ...
... In contrast, sand martins breeding in Hungary used the eastern Afro-Palearctic flyway via the Balkan peninsula, the eastern Mediterranean Sea and crossed the central part of the Sahara (Libya) to overwinter in the lake Chad basin, central Africa (Fig. 1). Both Hungarian birds remained stationary for the entire nonbreeding period and did not show site-itinerancy (similar to [24]). Thus, individuals originating from the same breeding sites overwintered in close vicinity to each other, and nonbreeding ranges of the populations were clearly separated by about 1300 km (Fig. 1). ...
... Moreover, information about sex-specific nonbreeding ranges or divergent behaviour during the nonbreeding period in Africa is not (yet) available. Assuming the migration pattern of our tracked females is representative for both females and males of the respective study population, sand martins are likely to use delimited, population-specific regions during the nonbreeding period (see also [24]) indicating high degree of migratory connectivity. In Palaearctic Barn swallows (Hirundo rustica) with comparable degree of migratory connectivity, residence sites during the nonbreeding periods did not differ between sexes [36]. ...
Full-text available
Background Populations of long-distance migratory birds experience different environments and are consequently exposed to different parasites throughout their annual cycles. Though, specific whereabouts and accompanied host-parasite interactions remain unknown for most migratory passerines. Collared sand martins (Riparia riparia) breeding in the western Palaearctic spend the nonbreeding period in Africa, but it is not yet clear whether specific populations differ in overwintering locations and whether these also result in varying infections with vector-transmitted endoparasites. Results Geolocator tracking revealed that collared sand martins from northern-central and central-eastern Europe migrate to distant nonbreeding sites in West Africa and the Lake Chad basin in central Africa, respectively. While the ranges of these populations were clearly separated throughout the year, they consistently spent up to 60% of the annual cycle in Africa. Ambient light recorded by geolocators further indicated unsheltered roosting during the nonbreeding season in Africa compared to the breeding season in Europe. We found 5–26% prevalence of haemosporidian parasites in three breeding populations and one migratory passage population that was only sampled but not tracked. In total, we identified seven Plasmodium and nine Haemoproteus lineages (incl. two and seven new lineages, respectively), the latter presumably typical for swallows (Hirundinae) hosts. 99.5% of infections had a low intensity, typical for chronic infection stages, whereas three individuals (0.5%) showed high parasitaemia typical for acute infections during spring migration and breeding. Conclusions Our study shows that blood parasite infections are common in several western Palaearctic breeding populations of collared sand martins who spent the nonbreeding season in West Africa and the lake Chad region. Due to long residency at the nonbreeding grounds blood parasite transmissions may mainly occur at host population-specific residences sites in Europe and Africa; the latter being likely facilitated by unsheltered roosting and thus high vulnerability to hematophagous insects. The rare cases of high parasitaemia during spring migration and breeding further indicates either relapses of chronic infection or primary infections which occurred shortly before migration and during breeding.
... we found a lower survival rate in tagged than in control birds, which resembles previous findings with aerial insectivores Szép et al., 2017;Morganti et al., 2018). In order to reduce this negative effect, we attached geolocators without light stalks in 2017 and 2018 (Bowlin et al., 2010;Scandolara et al., 2014;Costantini & Møller, 2013;Morganti et al., 2018). ...
... Barn Swallows breeding in southwestern Spain arrived at their wintering areas in Africa at the beginning of September, some 1-2 months earlier than reported for other European populations Arizaga et al., 2015;Klvaňa et al., 2018;Briedis et al., 2018). The overwintering period lasted about five months, which matches previous results found for hirundines Arizaga et al., 2015;Szép et al., 2017;Klvaňa et al., 2018;Briedis et al., 2018). we also found that some of the tagged individuals remained at a single wintering location whereas others performed significant within-winter movements in west Africa (see Supplementary Material, Appendix 2). ...
... hence, the tagged Barn Swallows arrived at their breeding colonies mainly in mid-february, again some two months earlier than reported for other European populations Arizaga et al., 2015;Briedis et al., 2018). previous studies on hirundines have shown that the onset of autumn migration is more synchronised among individuals than both the onset of spring migration and the arrival time at the breeding areas Arizaga et al., 2015;Szép et al., 2017). here we found a similar pattern, which may help to explain carry-over effects from the winter to the breeding stage (norris & Marra, 2007;harrison et al., 2011). ...
Many populations of migratory bird species are rapidly declining. As a requisite for targeting effective conservation efforts it is essential to determine the whereabouts of migrants yearround. However, our knowledge of migratory routes and spatial-temporal occurrence across periods of the annual cycle is still limited for most species. We used light-level geolocators to describe in detail the migration system of Barn Swallows Hirundo rustica breeding in southwestern Spain and wintering across west Africa. We were able to successfully retrieve year-round data for 38 individuals and reconstructed their migratory routes using FLightR R package. Many of the studied individuals remained for some time in summer wandering through southern Spain and northern Morocco, a period that we defined as pre-migration. The studied swallows started their autumn migration on average on August 18th, stopping over to refuel in northwestern Morocco and southern Mali. On average the tagged individuals arrived on September 3rd at their wintering areas, which were located across Ivory Coast and surrounding countries, in localities dominated by savannahs, grasslands and crops. After wintering, swallows started the spring migration January 26th on average, stopping over in Senegal and Mauritania. They arrived back at the Spanish breeding colonies february 18th on average (from mid-January to mid-March). Surprisingly, during the autumn migration, one of the tagged individuals travelled to England before returning south and spending a short wintering period in northwestern Spain.
... -Sand Martins Riparia riparia from eastern Europe spent their full winter period in the surroundings of Lake Chad and the nearby Waza Logone floodplains (Szép et al. 2017, Hahn et al. 2021). ...
... -Common House Martin Delichon urbicum (Szép et al. 2017). -Willow Warbler from Siberia passing through Sudan (Sokolovskis et al. 2018). ...
Full-text available
Many migratory bird species cross the Mediterranean during autumn migration, but most do so either at the western or eastern ends where they can avoid, or minimise, sea crossings. The intervening 3500 km has long sea crossings, probably adding to the barrier imposed by the Sahara. If this were the general migration pattern, it would result in high concentrations of Afro-Palearctic migrants in West and East Africa and fewer in the central sub-Saharan zones. Unless migrants reorientate upon reaching the sub-Sahara, densities of migratory birds in the central Sahel should be much lower than at either end of the African savannah range. The available studies of birds equipped with GPS or geolocators show that south of the Sahara at least some species perform lateral movements to some extent. However, many remain either in the Sahel’s western or eastern parts or continue moving southwards along the same longitudinal axis. We use density counts of arboreal birds from across the full width of the Sahel to explore the extent to which the central Sahel zone is underused by migratory birds. Eleven out of twelve common migratory arboreal species occurred at lower densities in the central Sahel than could be explained by tree-related variables. Western Bonelli’s Warbler Phylloscopus bonelli, Western Orphean Warbler Curruca hortensis and Subalpine Warbler Curruca cantillans were most common in the western and (much) less common in the central Sahel, whereas Eastern Olivaceous Warbler Iduna pallida, Eastern Orphean Warbler Curruca crassirostris, Lesser Whitethroat Curruca curruca and Rüppell’s Warbler Curruca ruppeli were most common in eastern, but less so in the central Sahel. Woodchat Shrike Lanius senator and Common Redstart Phoenicurus phoenicurus were more common in the western and eastern parts than in the central Sahel. No longitudinal variation was found for Common Whitethroat Curruca communis, which is consistent with the knowledge that many cross the Mediterranean waters upon encountering them. The conclusion is justified that the central Sahel is underused by migratory birds and by consequence, as far as these birds are concerned, not ‘saturated’. The question arises whether in the past, when the number of migratory birds was much greater than today, there might not have been a Gap of Chad.
... Eine Analyse von stabilen Isotopen aus Federn niederländischer Brutvögel lässt auf Mauserregionen im Bereich von Kamerun und dem Kongo-Becken schließen (Hobson et al. 2012). Die bisher einzige veröffentlichte Studie zum individuellen Zugverhalten konnte für fünf ungarische Mehlschwalben Überwinterungsorte nachweisen, die von Zentralafrika bis nach Ost-und Südostafrika streuten (Szép et al. 2017). Für die Mehlschwalben, die in Deutschland brüten, ist unser Wissen zu Aufenthaltsorten außerhalb der Brutzeit dürftig. ...
Full-text available
Common House Martins are long-distance migrants that spend their non-breeding season in western and southern Africa. The recovery rates of ringed birds on migration and in the wintering areas are very low. 23 recoveries of birds ringed in eastern Germany and found outside the breeding season at distances of more than 100 km showed autumn migration directions from SW to SE, with SW dominating. From the putative wintering area, there are only three recoveries from the DR Congo, Zambia and Botswana. Data from two tracked Common House Martins from a breeding colony in Saxony-Anhalt showed an autumn migration in SSE/SE direction. The wintering areas of these birds were about 4,000 km apart in western and south-western Africa. Within the wintering areas, both birds did not stay within a classical, narrow residence site but possibly roamed across a wider area.
... The reason for this is not known, but the phenomenon of loop migration is one of the possible causes. During loop migration, birds do not use the same routes for spring and autumn migration, as has been shown in several different bird species using different methods (Gill et al. 2009;Klaassen et al. 2010;Szép et al. 2017;Tøttrup et al. 2017;Jónás et al. 2018). The exact cause of this is not known, but prevailing winds during migration and/or variation in food availability might play a role (Gauthreaux et al. 2006;Shaffer et al. 2006;Klaassen et al. 2011;Thorup et al. 2017;Tøttrup et al. 2017). ...
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Bird migration is a highly complex, regulated process, of which timing is an essential element. The timing of migration is influenced by moult, age, sex and food of the birds, as well as the distance between the breeding and wintering sites. In this study, we used data from a ringing station on the shores of Lake Baikal to investigate factors influencing migration timing for species with different migration and moulting strategies, wintering sites and feeding habits. In general, we found that the migration of Passerine across Lake Baikal is influenced by similar factors to those of other migratory species in other migratory flyways. For most species, adult birds migrated through the area earlier in both spring and autumn. In spring, protandrous migration was detected for most of the species, while in autumn, differences in migration timing were less common. Migratory birds migrate later in spring and earlier in autumn, the longer the distance between nesting and wintering sites. It is important to highlight, however, that in both seasons only moulting, sex and food type had an equal influence on the timing of migration, while migration distance and age regulated migration in only one season or the other. In both spring and autumn, we observed differences in the timing of the migration of different species. Studies on the migration of north Asian Passerines are important in the future as the populations of several once common species have declined dramatically in recent times.
... Some of the bird species do not use the same routes for spring and autumn migration because of the seasonal differences in prevailing winds during migration and/or variation in food availability (Gauthreaux et al. 2006;Shaffer et al. 2006;Klaassen et al. 2011;Thorup et al. 2017;Tøttrup et al. 2017). This migration pattern is called loop migration, and a number of bird species in different migration systems use this strategy (Phillips 1975;Gill et al. 2009;Klaassen et al. 2010;Szép et al. 2017;Tøttrup et al. 2017). Loop migration has been detected mainly from recaptures and the data on birds tagged with different tracking techniques. ...
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The East Asian-Australasian bird migration system is one of the most species-rich migration systems, nevertheless, we have very little information on the migration of the species that use the Asian-Australasian Flyway. Most knowledge is available about waterfowls (cranes, ducks). However, very little is known about songbirds, mainly due to the lack of large-scale, long-term ringing activities. Most of what we know about the migration of these species is based primarily on field observations and the results of the Migratory Animal Pathological Survey (MAPS) conducted in the 1960s and 1970s. In the 2010s, however, several local ringing projects started. They produced considerable knowledge about the migration of songbirds. More recently, geolocators have also aided researchers in their work, providing even more accurate data on the migratory routes and migratory habits of species. The present study summarises the data we have obtained over the past decade about the migration of long-distance migratory songbirds nesting in North Asia. The article is based primarily on the data collected at ringing stations in the Far Eastern Russia, complemented by research from other areas in East and Southeast Asia. This review highlights the need for further research to ensure long-term protection of species that, at times, show a drastic decline in numbers.
... This pattern has been described using bird ringing data and tracking data based on geolocators in various migratory systems, e.g. Selasphorus hummingbirds (Phillips 1975), Marsh Harrier Circus aeruginosus (Klaassen et al. 2010), Bar-tailed Godwit Limosa lapponica (Gill et al. 2009), Sand Martin Riparia riparia (Szép et al. 2017) and Red-backed Shrike Lanius collurio . ...
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Loop migration, i.e. the use of different routes during spring and autumn migration, is a common migratory strategy among many long-distance migratory species. This migration strategy is most likely driven by the variation in food availability and/or prevailing winds en route between the spring and autumn seasons. Tracking studies and long-distance ring recoveries have revealed that many of the species that migrate along the American and Eurasian−African migratory flyways use different stopover sites in spring and in autumn. However, very little information is available on songbirds migrating along the East Asian flyway. In this study, we compared the wing lengths of six East Asian long-distance migratory passerines (Red-flanked Bluetail Tarsiger cyanurus, Siberian Rubythroat Calliope calliope, Taiga Flycatcher Ficedula albicilla, Arctic Warbler Phylloscopus borealis, Thick-billed Warbler Arundinax aedon and Black-faced Bunting Emberiza spodocephala) migrating through two different study sites in Russia. We examined whether these species show morphological differences between spring and autumn migration which could indicate the occurrence of different populations at different parts of the migratory cycle. Based on a dataset of 2,368 adult individuals, we found no differences in wing length between the two seasons for four studied species, suggesting the absence of loop migration. This might be explained by adequate food supply and similar prevailing wind directions for birds in both spring and autumn, or the lack of obvious ecological barriers along the East Asian flyway which have to be crossed during migration. However, the differing wing lengths of individuals captured in spring and autumn for two species, Black-faced Bunting and Red-flanked Bluetail, provide evidence for the possible use of different seasonal migratory routes. Further field studies are needed to better understand the migration ecology of passerine birds in the East Asian flyway.
... UK: [29]; Austria: [30] [25]) are indicated with an arrow: a absence of j3 setae, b broad sternal shield with two pairs of setae been caused by this lineage, indicating its long history (non-emergence). It is well-documented that house martins in Hungary migrate to and from Africa via the eastern Mediterranean region, including Israel [31]. Thus, the very close molecular-phylogenetic relationship between the Hungarian and Israeli isolates of O. sylviarum, as demonstrated here, strongly supports our hypothesis that (at least in Hungary) long-distance dispersal and "synanthropic arrival" should be highly relevant in the case of the permanently parasitic O. sylviarum via natural bird migration (as opposed to D. gallinae, with human transportation playing a role in its dispersal events). ...
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Background Among Dermanyssoidea, the chicken red mite ( Dermanyssus gallinae ) and the northern fowl mite ( Ornithonyssus sylviarum ) are considered to be the cause of high economic losses endured by the poultry industry in the Holarctic region, with O. sylviarum predominating in North America and D. gallinae in Europe. Both species have a short life-cycle (thereby allowing a rapid build-up of massive infestations), a wide range of hosts, synanthropic presence and the ability to bite humans. The aim of this study was to analyze dermanyssoid mite specimens, collected in two human dwellings and two racing pigeon premises in different urban areas in Hungary, with molecular–phylogenetic methods. Methods Mite species were identified morphologically. This was followed by DNA extraction and molecular–phylogenetic analyses of selected mites, based on the cytochrome c oxidase subunit I ( cox 1) and 28S rRNA ( 28S ) genes. Results Mites that had invaded a home from a pigeon nest and were linked to human dermatitis were morphologically and molecularly identified as D. gallinae special lineage L1. Specimens collected at all other sampling sites were identified as O. sylviarum , including mites that had invaded a home from a house martin ( Delichon urbicum ) nest, as well as those which were collected from racing pigeons. House martin- or pigeon-associated O. sylviarum specimens showed the highest sequence identity and closest phylogenetic relationship with conspecific mites reported in GenBank from Israel or Canada, respectively. Conclusions Detailed morphological and molecular–phylogenetic analyses of D. gallinae lineage L1 confirmed its status as a cryptic species within D. gallinae ( s.l. ). Taking into account the well-documented latitudinal migratory routes of house martins between Hungary and Africa, O. sylviarum associated with this bird species most likely arrived on its host from the eastern Mediterranean region. On the other hand, mites collected from pigeons in Hungary showed cox 1 genetic homogeneity with North American O. sylviarum , which can only be explained by a long-distance (west-to-east intercontinental) connection of birds and their mites as part of human activity (e.g. transportation to exhibitions or trading). In summary, this is the first molecularly confirmed and phylogenetically analyzed case of O. sylviarum infestation of birds in Hungary, implicating urban environment and involving distant parts of the country. This is also the first report of D. gallinae lineage L1 in central Europe.
... For small migratory birds, typically two methods have been used to identify wintering locations, migratory connectivity and fidelity. The first is to attach archival light-weight electronic tracking units, like geolocators (Stutchbury et al. 2009b;English et al. 2017;Szép et al. 2017) or GPS tags Fraser et al. 2017), to migrating birds. These tracking units provide critical information on winter locations and connectivity that can inform conservation decisions (Renfrew et al. 2013;Finch et al. 2015;Cooper et al. 2017). ...
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Swallows and other aerial insectivores are experiencing steep population declines, potentially as a result of decreased insect availability during breeding and poor non-breeding conditions. To determine the likely drivers of decline for Bank Riparia riparia, Barn Hirundo rustica, Cliff Petrochelidon pyrrhonoto and Tree Swallows Tachycineta bicolor and Purple Martins Progne subis and whether they were common to multiple species, I: 1) examined the relationships between insect abundance and swallow breeding success (2014-2015); 2) compared breeding phenology and performance before (1962-1972) and after (2006-2016) the onset of population declines; 3) examined relationships between non-breeding conditions and potential carry-over effects (2014-2016); 4) identified winter locations; and 5) reviewed the effect of several threats on adult survival. Insect abundance was not related to Barn, Cliff and Tree Swallow nestling survival or mass suggesting that it did not limit breeding success. Between 1962-1972 and 2006-2016, I found that Barn, Cliff and Tree Swallows bred 8-10 days earlier and had unchanged or higher performance. In contrast, Bank Swallows did not breed earlier and had lower performance. Poor non-breeding conditions, particularly low rainfall, resulted in carry-over effects during breeding (i.e., lower mass, later breeding or lower performance) for Barn and Cliff Swallows; these conditions were related to higher mass, but later breeding and lower performance for Bank Swallows. Stable isotope and geolocator results indicated that Bank, Barn and Cliff Swallows likely winter throughout Brazil, Bolivia, Paraguay, Uruguay and Argentina. While little information is available on relationships between threats and adult survival, poor weather is related to lower survival for all species except Purple Martins. Low insect abundance during the breeding season is likely not contributing to population declines for Barn, Cliff and Tree Swallows, but, for Bank Swallows, declines may be partly due to a mis-timing between food availability and breeding. Also, for Bank, Barn and Cliff Swallows, poor non-breeding conditions are associated with carry-over effects on breeding, including lower success. Poor non-breeding conditions may also contribute to population declines through lower adult survival. While there are some similarities in the response of many species to different potential drivers, Bank Swallows often differed in their response.
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Aim Knowledge of broad‐scale biogeographical patterns of animal migration is important for understanding ecological drivers of migratory behaviours. Here, we present a flyway‐scale assessment of the spatial structure and seasonal dynamics of the Afro‐Palaearctic bird migration system and explore how phenology of the environment guides long‐distance migration. Location Europe and Africa. Time period 2009–2017. Major taxa studied Birds. Methods We compiled an individual‐based dataset comprising 23 passerine and near‐passerine species of 55 European breeding populations, in which a total of 564 individuals were tracked during migration between Europe and sub‐Saharan Africa. In addition, we used remotely sensed primary productivity data (the normalized difference vegetation index) to estimate the timing of vegetation green‐up in spring and senescence in autumn across Europe. First, we described how individual breeding and non‐breeding sites and the migratory flyways link geographically. Second, we examined how the timing of migration along the two major Afro‐Palaearctic flyways is tuned with vegetation phenology at the breeding sites. Results We found the longitudes of individual breeding and non‐breeding sites to be related in a strongly positive manner, whereas the latitudes of breeding and non‐breeding sites were related negatively. In autumn, migration commenced ahead of vegetation senescence, and the timing of migration was 5–7 days earlier along the Western flyway compared with the Eastern flyway. In spring, the time of arrival at breeding sites was c . 1.5 days later for each degree northwards and 6–7 days later along the Eastern compared with the Western flyway, reflecting the later spring green‐up at higher latitudes and more eastern longitudes. Main conclusions Migration of the Afro‐Palaearctic landbirds follows a longitudinally parallel leapfrog migration pattern, whereby migrants track vegetation green‐up in spring but depart before vegetation senescence in autumn. The degree of continentality along migration routes and at the breeding sites of the birds influences the timing of migration on a broad scale.
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Over decades it has been unclear how individual migratory songbirds cross large ecological barriers such as seas or deserts. By deploying light-level geolocators on four songbird species weighing only about 12 g, we found that these otherwise mainly nocturnal migrants seem to regularly extend their nocturnal flights into the day when crossing the Sahara Desert and the Mediterranean Sea. The proportion of the proposed diurnally flying birds gradually declined over the day with similar landing patterns in autumn and spring. The prolonged flights were slightly more frequent in spring than in autumn, suggesting tighter migratory schedules when returning to breeding sites. Often we found several patterns for barrier crossing for the same individual in autumn compared to the spring journey. As only a small proportion of the birds flew strictly during the night and even some individuals might have flown non-stop, we suggest that prolonged endurance flights are not an exception even in small migratory species. We emphasise an individual’s ability to perform both diurnal and nocturnal migration when facing the challenge of crossing a large ecological barrier to successfully complete a migratory journey.
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1. Determining global position by light measurements (‘geolocation’) has revolutionised the methods used to trackmigratory birds throughout their annual cycle. 2. To date, there is no standard way of analysing geolocator data, making communication of analyses cumbersome and hampering the reproducibility of results. 3. We have, therefore, developed the R package GeoLight, which provides basic functions for all steps of determining global positioning and a new approach in analysingmovement pattern. 4. Here, we briefly introduce and discuss the major functions of this package using example movement data of European hoopoe (Upupa epops).
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Based on the Hungarian common bird monitoring scheme (MMM), which is the longest running country-wide monitoring using formal sampling design with representative data for the main habitats in Central-Eastern Europe, we investigated the population trends of common breeding and wintering species. Habitat preference and occupancy of the common breeders, migration strategies and relationships among these characteristics could act behind the population trends. We pointed out that long distance migrant bird species had strong decreasing trends in Hungary and very probably in the entire Pannonian biogeographical region, whereas the partial and short migrant species has increasing trends. Farmland birds had declining trend, which trend became more obvious since the joining of Hungary to the EU. The negative changes in the farmland habitat could influence bird species nesting/foraging mainly in this habitat independently from their migration strategies. Our investigations let us to develop indicators on the basis of migration strategy and habitat usage of common birds to provide regular information about condition of groups of species and their habitats in Hungary and the Pannonian region. The MMM database provide unique opportunity for further investigations of several species, habitats and area specific in a part of Europe where this kind of information is rare yet.
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Geolocators are small light-weight data loggers used to track individual migratory routes, and their use has increased exponentially in birds. However, the effects of geolocators on individual performance are still poorly known. We studied geolocator effects on a long-distance migrating passerine bird, the northern wheatear (Oenanthe oenanthe L.). We asked the general question of whether geolocators affect migratory behaviour and subsequent reproductive performance of small passerines by comparing arrival time, breeding time, breeding success and survival of geolocator versus control birds of known identity and breeding history. During two years geolocator birds (n=37) displayed a lower apparent survival (30%) as compared to controls (45%, n=164). Furthermore, returning geolocator birds (n=12) arrived on average 3.5 days later, started laying eggs 6.3 days later, and had lower nest success (25%) than control birds (78%). Our results suggest that geolocators affect migratory performance with carry-over effects to the timing of breeding and reproductive success in the subsequent breeding season. We discuss the implications of such geolocator effects for the study of migratory strategies of small passerines in general and suggest how to identify and investigate such effects in the future.
The populations of farmland birds in Europe declined markedly during the last quarter of the 20th century, representing a severe threat to biodiversity. Here, we assess whether declines in the populations and ranges of farmland birds across Europe reflect differences in agricultural intensity, which arise largely through differences in political history. Population and range changes were modelled in terms of a number of indices of agricultural intensity. Population declines and range contractions were significantly greater in countries with more intensive agriculture, and significantly higher in the European Union (EU) than in former communist countries. Cereal yield alone explained over 30% of the variation in population trends. The results suggest that recent trends in agriculture have had deleterious and measurable effects on bird populations on a continental scale. We predict that the introduction of EU agricultural policies into former communist countries hoping to accede to the EU in the near future will result in significant declines in the important bird populations there.
We investigated sex- and year-dependent variation in the temporal and spatial movement pattern of barn swallows Hirundo rustica during the non-breeding period. Hundred and three individuals equipped with miniaturized light-level geolocators at three different breeding areas in southern Switzerland and northern Italy provided data for the analysis. We identified a region 1000 km in radius centred in Cameroon as the main non-breeding residence area of these three geographical populations. Five residence areas of males only were in southern Africa, south of 19°S. Most individuals occupied a single site during their stay south of the Sahara. The timing of migration broadly overlapped between sexes and all geographical breeding populations. Between the two study years there was a distinct difference of 5 to 10 d in departure dates from and arrival at the breeding sites. Remarkably, the period of residence in sub-Saharan Africa was very similar (157 d) in the two study years, but their positions in the first year (2010–2011) were about 400 km more to the north than in the second (2011–2012). Independent of the year, individuals with sub-Saharan residence areas further north and east had a shorter pre-breeding migration and arrived earlier than those staying further south and west. In addition, birds breeding in southern Switzerland arrived at their breeding colony 7–10 d later than those breeding only 100 km south, in the Po river plain. Our study provides new information on the variance in migration phenology and the distribution of residence areas in sub-Saharan Africa in relation to sex, population and year. It supports the usefulness of light-level geolocators for the study of annual routines of large samples of small birds.
The importance of cavities as roost sites in migratory species is often unknown because it is challenging to monitor cavity use during the non-breeding period. We documented cavity use throughout the annual cycle of a woodpecker using light-level geolocators. Northern Flickers Colaptes auratus spent 63–90% of nights roosting in a cavity throughout the year, including during migration. The high frequency of year-round cavity use by Flickers suggests that cavities provide benefits beyond nest-sites. Our work highlights the potential use of geolocators to examine cavity use.
Miniaturized light-level geolocators may revolutionise the study of avian migration. However, there are increasing concerns that they might negatively affect fitness. We investigated the impact of two miniaturized geolocator models (SOI-GDL2.10, deployed in 2010, and SOI-GDL2.11, deployed in 2011) on fitness traits of the barn swallow Hirundo rustica, one of the smallest migratory species to which geolocators have been applied to date. The 2011 model was lighter (by 0.09 g) and had a shorter light stalk compared to the 2010 model. Using data from 640 geolocator and 399 control individuals from three geographical populations, we found that geolocators reduced annual survival probabilities (control birds: 0.19–0.63; geolocator birds: 0.08–0.40, depending on year, sex, and how birds that lost the device were considered), with more markedly negative effects on females equipped with the 2010 model. In addition, among birds equipped with the 2010 model, onset of reproduction in the subsequent year was delayed (by 12 d) and females laid smaller first clutches (by 1.5 eggs, i.e. a 30% reduction) compared to controls. Equipping parents with geolocators while they were attending their brood did not affect nestling body mass or fledging success. A reduction of geolocator weight and drag by shortening the light stalk slightly enhanced the survival of females but not that of males, and mitigated the negative carry-over effects on subsequent reproduction. Our study shows that geolocators can have a negative impact on survival and reproduction, and that even minor differences in weight and drag can make the difference. We suggest that studies aiming at deploying geolocators or other year-round tagging devices should be preceded by pilot experiments to test for fitness effects.
There is compelling evidence that Afro-Palaearctic (A-P) migrant bird populations have declined in Europe in recent decades, often to a greater degree than resident or short-distance migrants. There appear to have been two phases of decline. The first in the 1960s–1970s, and in some cases into the early 1980s, largely affected species wintering predominantly in the arid Sahelian zone, and the second since the 1980s has mostly affected species wintering in the humid tropics and Guinea forest zone. Potential drivers of these declines are diverse and are spread across and interact within the migratory cycle. Our knowledge of declining species is generally better for the breeding than the non-breeding parts of their life cycles, but there are significant gaps in both for many species. On the breeding grounds, degradation of breeding habitats is the factor affecting the demography of the largest number of species, particularly within agricultural systems and woodland and forests. In the non-breeding areas, the interacting factors of anthropogenic habitat degradation and climatic conditions, particularly drought in the Sahel zone, appear to be the most important factors. Based on our synthesis of existing information, we suggest four priorities for further research: (1) use of new and emerging tracking technologies to identify migratory pathways and strategies, understand migratory connectivity and enable field research to be targeted more effectively; (2) undertake detailed field studies in sub-Saharan Africa and at staging sites, where we understand little about distribution patterns, habitat use and foraging ecology; (3) make better use of the wealth of data from the European breeding grounds to explore spatial and temporal patterns in demographic parameters and relate these to migratory pathways and large-scale patterns of habitat change and climatic factors; and (4) make better use of remote sensing to improve our understanding of how and where land cover is changing across these extensive areas and how this impacts A-P migrants. This research needs to inform and underpin a flyway approach to conservation, evaluating a suite of drivers across the migratory cycle and combining this with an understanding of land management practices that integrate the needs of birds and people in these areas.