Ringing & Migration, 2013 Vol. 28, No. 1, 39–42, http://dx.doi.org/10.1080/03078698.2013.811118
SHORT REPORT
Spring migration phenology and arrival conditions of the Eastern Bonelli’s Warbler and the Semi-collared Flycatcher at a small Greek island CHRISTOS BARBOUTIS1,2*, ANGELOS EVANGELIDIS1, TRIANTAPHYLLOS AKRIOTIS3 and THORD FRANSSON4 1 Antikythira Bird Observatory, Hellenic Ornithological Society, Themistokleous 80, GR-10681, Athens, Greece 2Natural History Museum of Crete, University of Crete, PO Box 2208, 71409 Heraklion, Crete, Greece 3Department of Environmental Science, University of the Aegean, GR-81100 Mytilini, Greece 4Department of Environmental Research and Monitoring, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden In this study, we examined the spring migration phenology and arrival body mass and fat score of two longdistance migrants, the Eastern Bonelli’s Warbler Phylloscopus orientalis and the Semi-collared Flycatcher Ficedula semitorquata at a small Greek island. Our data indicate a regular and early spring passage of both species through the area, with the Semi-collared Flycatcher peaking in late March and early April and the Eastern Bonelli’s Warbler about a week later. The arrival body masses of both species were lower than any other mean value of body mass previously reported. This, along with the low fat loads of both species, indicates that the birds’ reserves are depleted after crossing the Mediterranean Sea and suggests that they had probably not refuelled after the desert crossing.
In spring, within the European–African bird migration system, most birds make a fast return trip from their wintering quarters to their breeding sites (Fransson 1995, Yohannes et al 2009). It has been estimated that it will take four to five nights of flight, following the eastern flyway, to cross both the Sahara Desert and the eastern Mediterranean (Barboutis et al 2011a). Passerines arriving with depleted fuel reserves after crossing the Sahara Desert and the Mediterranean Sea have been reported several times in central and eastern areas of the Mediterranean (Moreau 1969, Schwilch et al 2002, Barboutis et al 2011b). Two poorly studied long-distance Palearctic migrant species that undertake this barrier crossing are the Eastern Bonelli’s Warbler Phylloscopus orientalis and the Semicollared Flycatcher Ficedula semitorquata. The Eastern Bonelli’s Warbler breeds in southeastern Europe from southern Croatia to Albania and northern Greece to southern Romania, and in western and southwestern Turkey, while the Semi-collared Flycatcher breeds in Albania, Bulgaria, Greece and Turkey, and from the
* Correspondence author Email:
[email protected]
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Caucasus to northwestern Iran. Both species winter in subSaharan Africa (del Hoyo et al 2006). They are also among the least known of European birds, particularly with respect to migration and morphometrics (Cramp & Perrins 1993). The aim of this study was to provide basic data on the phenology of spring migration and morphometrics just after their crossing of the Mediterranean Sea. Data were collected at Antikythira Bird Observatory within the standardised programme for ringing of migrants run by the Hellenic Ornithological Society and the Hellenic Bird Ringing Centre from the end of March until the end of May, within the period 2007– 12. Antikythira (35°51’N 23°18’E) is located between the southern tip of mainland Greece and western Crete, 355 km from the North African coast (Fig 1). Trapped birds were aged according to Svensson (1992) and weighed to the nearest 0.1 g. Maximum-chord wing length and tarsus length (Svensson 1992) were recorded as measurements of size to the nearest 0.5 mm. Fat was scored according to Kaiser (1993). When the criteria for parametric tests were met they were chosen to compare morphometrics between age and sex classes in Semi-collared Flycatcher; in other cases, the equivalent non-parametric tests were performed. Significance was set at P < 0.05 and
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Figure 2. Spring migration phenology of Eastern Bonelli’s Warblers and Semi-collared Flycatchers through Antikythira. Median passage dates are shown with dashed line.
Figure 1. The location of Antikythira in the eastern Mediterranean.
analyses were performed using PAST v2.17 (Hammer et al 2001). In total, 94 Eastern Bonelli’s Warblers and 63 Semicollared Flycatchers were trapped between 2007 and 2012. Of the 63 Semi-collared Flycatchers, 41 were sexed as males, 21 as females and one individual remained undetermined. With respect to age, 26 were older than second calendar year (hereafter adults) and 30 were in their second calendar year (hereafter firstyear birds), while seven birds were not aged. The median date of spring passage of the Eastern Bonelli’s Warbler on Antikythira was 4 April (1st, 3rd quartiles: 2 April, 14 April), with the earliest bird trapped on 21 March 2008 and the latest on 8 May 2010 (Fig 2). The median date for the Semi-collared Flycatcher was 2 April (1st, 3rd quartiles: 26 March, 15 April) with the earliest individual trapped on 23 March 2010 and the latest on 10 May 2011 (Fig 2). The median migration date of male Semi-collared Flycatchers was 1 April and the median passage date of females was 2 April; the median passage dates of adults and first-year birds were 1 April and 5 April, respectively. The differences in median passage dates between sexes (Mann–Whitney Q 2013 British Trust for Ornithology, Ringing & Migration, 28, 39–42
U-test, Z = -1.28, P = 0.199) and between age classes (Z = -0.188, P = 0.06) were not statistically significant. The fuel load of birds trapped, based on scoring of visible fat, was very low for both species (Table 1). The proportion of birds with fat scores 0 and 1 was 78.9% in the Semicollared Flycatcher and 54.5% in the Eastern Bonelli’s Warbler. The mean arrival body mass was 11.2 g for Semi-collared Flycatcher and 6.9 g for Eastern Bonelli’s Warbler (Table 1). Body mass differed significantly (Mann–Whitney U-test, Z = -2.55, n = 60, P = 0.011) between male (11.4 ± 1.1 g) and female (10.8 ± 0.5 g) Semi-collared Flycatchers, while there was no significant difference between age classes (Z = -0.66, n = 53, P = 0.53). Male Semi-collared Flycatchers had on average significantly longer wings than females (t56 = - 3.29, P = 0.002; males: 83.8 ± 1.9 mm, females: 82.0 ± 2.2 mm), while no significant difference was detected between age classes (t50 = 0.49, P = 0.62). Wing length decreased significantly with the progression of the migration season in the Eastern Bonelli’s Warbler (Spearman r = -0.211, P = 0.046, n = 90), while there was no change in body mass with advancing date (r = -0.195, P = 0.061, n = 93). For the Semi-collared Flycatcher there were no changes in wing length (r = -0.179, P = 0.18, n = 59) or body mass (r = -0.023, P = 0.86, n = 60) with advancing date.
Spring migration on Antikythira
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Table 1. Morphometrics and fat score for Semi-collared Flycatchers and Eastern Bonelli’s Warblers at Antikythira during spring migration. Semi-collared Flycatcher
Eastern Bonelli’s Warbler
N
Mean ± SD
Range
N
Mean ± SD
Range
Wing length (mm)
53
83.4 ± 2.1
79.0–87.5
73
67.1 ± 2.9
57.5–74.0
Tarsus length (mm)
44
16.9 ± 0.6
15.9–18.3
67
17.6 ± 0.6
15.9–18.9
Tail length (mm)
20
52.7 ± 2.0
50.0–57.5
10
46.7 ± 2.4
41.0–51.0
Body mass (g)
54
11.1 ± 1.0
9.3–15.4
77
6.9 ± 0.6
5.7–8.3
Fat score
57
0.8 ± 1.1
0–3
88
1.6 ± 1.2
0–4
The timing of captures at Antikythira indicates a regular passage of both species through the area. Based on the seasonal distribution of birds trapped, it seems as if some birds may also arrive earlier, before ringing activity starts at Antikythira; this is likely to be more frequent in the Semi-collared Flycatcher (Fig 2). Eastern Bonelli’s Warblers have been reported as common throughout Egypt between mid March and mid May (Goodman & Meininger 1989), mainly between 16 March and 12 April at Bahig on the northern coast (Horner 1977). Thus the timing of migration in Egypt is in accordance with our results. In Egypt the passage of Semi-collared Flycatchers has been reported to last from mid March to mid May (Goodman & Meininger 1989) or from 19 March to 11 April on the northern coast (Horner 1977), whereas in Libya and Tunisia passage peaks in late April and in Malta and Sicily the main passage is from mid April to early May (Cramp & Perrins 1993). In Greece as a whole, it is believed that the passage of Pied Ficedula hypoleuca, Collared F. albicollis and Semi-collared Flycatchers is approximately simultaneous, from late March to mid May, peaking around mid April (Handrinos & Akriotis 1997). Thus, passage at Antikythira is apparently significantly earlier than would have been expected from the published information, our findings being similar to those for Egypt but earlier than those elsewhere in North Africa, Malta, Sicily and the rest of Greece. Both species were apparently lighter on average than they were at other sites for which there are published data. The mean value of body mass for the Semicollared Flycatcher at Antikythira was lower than any other mean or individual value reported for the species (Dunning 2008), while for the Eastern Bonelli’s Warbler only one bird had a lower body mass during spring migration in Cyprus (Flint & Stewart 1983) than the mean body mass of this species at Antikythira.
The observed fat scores for both species combined with the low body masses indicate that most individuals of both species had most probably not refuelled since they started the barrier crossing south of the Sahara Desert. Furthermore, we assume that birds arriving at Antikythira had arrived after a long flight over the sea and thus were in poorer condition than birds at other study sites. ACKNOWLEDGEMENTS This is contribution number 11 from Antikythira Bird Observatory – Hellenic Ornithological Society. Antikythira Bird Observatory is funded from the A.G. and A.P Leventis Foundation.
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(MS received 4 December 2012; accepted 7 February 2013)
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