Dies, J. I.

Revistes Catalanes amb Accés Obert

94 Spring migration in the western Mediterranean and NW Africa
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95European Robin
Range 
The European Robin is a polytypic species with up to 
eight races showing slight clinal changes in size and 
colour, which breeds from Atlantic Europe south to N 
Africa and east to W Siberia and N Iran (Cramp, 1988). 
Most populations are partially migratory, although 
Robins are totally migratory in the north-east and 
probably largely sedentary in the extreme south. There 
are notable winter concentrations in the Mediterrane-
an Basin, but it is scarce in N Africa south of the coastal 
strip and rare below 32°N (Cramp, 1988; Adriaensen 
& Dhondt, 1990; Pérez-Tris et al., 2000; Thévenot et 
al., 2003). As a consequence of differential migration, 
female European Robins outnumber males in southern 
wintering regions since the species shows a strong lati-
tudinal segregation of the sexes (Catry et al., 2004a).
The Robin does not breed at any of the study sites, 
but is a common wintering species in the wet Balear-
ics, N Morocco, Catalonia and on the larger islands of 
the dry Balearics (Cabrera, Formentera), although even 
there the majority of birds are migrants. In S Morocco 
and on the smallest islands no or very few wintering 
birds are present (L’Illa de l’Aire, Conillera, Els Colum-
brets, L’Illa Grossa and Las Chafarinas).
Migratory route
Ringing recoveries show a prevailing SW-NE direction 
in birds of the nominate rubecula range (fig. 1). There 
are two recoveries from southern Great Britain, possibly 
corresponding to the race melophilus, despite a lack of 
recoveries of this taxon from outside its range (Wern-
ham et al., 2002). Recoveries reach 61°N in the Scandi-
navian Peninsula and NW Russia, but do not occur far 
from the coast in Morocco and Algeria; the southern-
most recoveries are at 32°N in NW Morocco. 
The frequency and number of captures is lowest in 
Morocco and on Las Chafarinas, although similar val-
ues are found along the coast of the Iberian Peninsula 
and the Balearic Islands (fig. 2); the sole exception is 
Illa Grossa, which accounts for a large proportion of 
captures, probably due both to an important influx of 
migrants to coastal Spain and the island effect.
Phenology 
Migration through the W Mediterranean starts before 
the beginning of the study period, that is, usually early 
and mid-February (Cramp, 1988; Bueno, 1998; Tellería 
et al., 1999; Thévenot et al., 2003). During early March 
the influx of birds is still low and the main passage pe-
riod occurs between mid-March and early April (fig. 3). 
Data from Els Columbrets and L’Illa de l’Aire, where 
wintering birds are very scarce, confirm this phenologi-
cal pattern. Adults tend to pass marginally earlier than 
second-year birds, a pattern that is repeated in Cata-
lonia and on the Balearics (little data available from 
Morocco). In accordance with published data (Cramp, 
1988), passage decreases markedly during the second 
half of April and only a few stragglers occur as late as 
early May (fig. 3). In the Tyrrhenian Islands, however, 
spring migration is largely finished by the end of March 
(Pettersson et al., 1990; Spina et al., 1993).
Biometry and physical condition 
Mean third primary length ranges from 52.5-52.6 in 
Morocco to 54.5 in Catalonia, while the mean values 
for wing length vary from 69.8 in N Morocco to 72.4 
on Els Columbrets and in Catalonia, within the range 
reported from the C Mediterranean (table 1; Spina et 
al., 1993; Waldenström et al., 2004). Morphometric 
characteristics of the European Robin vary with geo-
graphical region, age and sex, with longer wings found 
in northern populations, adults and males (Domínguez 
et al., 2007). Third primary lengths show a significant 
decreasing trend over time (fig. 6), probably reflecting 
seasonal changes in the age and sex of migrants; the 
smallest values are recorded in Morocco. These results 
agree with the migration patterns documented for 
this species, with males arriving earlier on breeding 
grounds than females (Tøttrup & Thorup, 2008), and 
suggest some degree of differentiation in the popula-
tions present in Morocco and NE Spain.
Mean values for fat scores vary between 1.1 on 
Els Columbrets and 3.6 in N Morocco, while the mean 
body mass varies from 14.7 to 17.6 at the same sites 
(table 1). Fat shows a general temporal increase, al-
though the opposite is found in physical condition and 
mass (fig. 9), the latter probably due to the decrease in 
size indicated by third primary length. Mean fat is high-
est in N Morocco, intermediate in Catalonia and the 
wet Balearics, and lowest in the dry Balearics and, par-
ticularly, on Els Columbrets (fig. 9). Physical condition 
shows a similar pattern, although in this case Catalonia 
and the dry Balearics have similar values (fig. 7). Higher 
body mass and better physical condition in birds from 
the wet Balearics compared to the dry Balearics may 
reflect the higher proportion of wintering birds and 
greater habitat suitability in the former site (but also, 
see below). On the other hand, the fact that birds from 
the wet Balearics also have higher average body mass 
and are in better physical condition than in Catalonia 
could be explained by the need for birds trapped on 
islands to build up larger energetic reserves in order to 
cross the Mediterranean.
The mean body mass in birds crossing the C Medi-
terranean (mean 14.5, n = 2,390; Spina et al., 1993) is 
similar to that observed on Els Columbrets, but lower 
than in the Balearics. Birds from N Morocco show similar 
96 Spring migration in the western Mediterranean and NW Africa
values to those captured in N Tunisia during spring mi-
gration (mean 17.1, n = 19; Waldenström et al., 2004), 
indicating that overall mean body mass in N Africa is 
similar to that recorded in S Iberian Peninsula (mean 
16.5 in Gibraltar [n = 28; Finlayson, 1981] and 17.3 
on L’Illa Grossa [n = 52]), but higher than in Catalonia 
and on the Balearics. Robins, thus, seem to build up the 
greatest amounts of energetic reserves in S Spain and 
coastal NW Africa before moving northwards.
Stopover 
The percentage of retraps is highest in Catalonia 
and the wet Balearics, although the mean stopo-
ver length is similar in all areas (too little data from 
Morocco to be relevant; fig. 5). In all areas with 
available data, fuel deposition rates tend to be sig-
nificantly negative (table 2) and birds staying for a 
few days show significantly lower initial body mass 
than those not retrapped (fig. 5). These results sug-
gest that these areas do not offer good refuelling 
opportunities for migrating robins and do not sup-
port differences in habitat suitability between wet 
and dry Balearics. The higher proportion of retraps 
in Catalonia and the wet Balearics may respond to 
higher proportions of wintering birds in these areas, 
although the observed negative refuelling rates may 
reflect their inability to build up energetic reserves 
prior to migration.  
97European Robin
Figure 1. Map of recoveries 
of birds captured in the 
study area during the study 
period (March to May). 
Table 1. Mean (± SD), range and sample size of main biometric parameters according to area.
 n Wing Third primary Body mass Fat score
Catalonia 1,894 72.4 ± 1.9 (67.0-79.0)  54.5 ± 1.6 (49.5-60.0)  15.9 ± 1.6 (10.5-23.6)  2.3 ± 1.1 (0-6) 
Columbrets 446 72.4 ± 2.1 (65.0-78.5)  54.3 ± 1.8 (49.4-60.5)  14.7 ± 1.8 (10.5-20.7)  1.1 ± 1.1 (0-4) 
Balearics (dry) 5,966 71.7 ± 1.9 (63.0-79.5)  54.0 ± 1.7 (46.0-61.0)  15.4 ± 1.7 (9.9-24.1)  2.1 ± 1.1 (0-6) 
Balearics (wet) 103 71.9 ± 1.8 (68.5-75.5)  54.1 ± 1.4 (51.5-57.5)  16.6 ± 1.7 (13.0-23.7)  2.1 ± 0.9 (0-5) 
Chafarinas 0    
N Morocco 8 69.8 ± 1.6 (67.5-72.0)  52.6 ± 1.6 (51.0-55.0)  17.6 ± 0.8 (16.7-18.9)  3.6 ± 0.7 (3-5) 
S Morocco 2 71.0 ± 2.8 (69.0-73.0)  52.5 ± 2.1 (51.0-54.0)  15.9 ± 1.2 (15.0-16.7)  2.5 ± 0.7 (2-3)  
    
Table 2. Variation in fuel deposition rate (g / day) according to area and type of retraps involved (mean ± 95% CI and sample size are given).
 Catalonia Columbrets Balearics (dry) Balearics (wet) Chafarinas N Morocco
All retraps -0.12 ± 0.06 (332) -0.22 ± 0.18 (30) -0.25 ± 0.04 (738) 0.01 ± 0.16 (22)    
Retraps >1 day -0.01 ± 0.04 (242) -0.11 ± 0.16 (23) -0.10 ± 0.03 (527) 0.04 ± 0.09 (17)    
98 Spring migration in the western Mediterranean and NW Africa
Figure 2. Relative 
frequency of captures and 
mean daily numbers ac-
cording to site during the 
standard period 
(16 April to 15 May). 
Figure 3. Frequency of 
captures during the 
study period. 
Aiguamolls
Llobregat
Canal Vell
Alfacada
Punta de la Banya
Columbrets
Illa de Colom
Albufera d’Es Grau
Illa de l’Aire
Albufera d’Alcudia
Dragonera
Cabrera
Conillera
Formentera
Illa Grosa
Chafarines
Kerbacha
Larache
Sidi Bou Rhaba
Fguig
Jorf
Mean daily number of captures
0               1                2                3                4               5
0               20               40               60              80             100
Frequency
      Relative frequency                               Mean daily captures
                                    March                              April                             May
                        13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
Pentad
                                 Total (median date = 28/3; n = 11,384)              Adult (median date = 25/3; n = 2,155)
                                       2nd-year (median date = 29/3; n = 8,256)
25
20
15
10
5
0
%
 C
ap
tu
re
s
 Relative frequency                     Mean daily captures
99European Robin
Figure 4. Variation in body 
mass and fat score 
according to site during 
the standard period 
(16 April to 15 May).
Figure 5. Variation in body 
mass by trapping status, 
minimum stopover length 
and frequency of retraps 
according to area.
Aiguamolls (n = 49)
Llobregat (n = 20)
Canal Vell (n = 72)
Alfacada (n = 9)
Punta de la Banya (n = 5)
Columbrets (n = 234)
Illa de Colom (n = 32)
Albufera d’Es Grau (n = 6)
Illa de l’Aire (n = 536)
Albufera d’Alcudia
Dragonera (n = 28)
Cabrera (n = 360)
Conillera (n = 34)
Formentera (n = 11)
Illa Grosa (n = 52)
Chafarines
Kerbacha
Larache
Sidi Bou Rhaba
Fguig
Jorf
Fat score (± 95% CI)
0              1              2              3              4              5
13         14          15         16         17         18          19
Body mass (±  95% CI)
     Body mass
20
18
16
14
12
10
8
6
   Catalonia   Columbrets  Balearics (d)   Balearics (w)   Chafarinas   N Morocco
17.4% (2,000)  3.5% (991)  12.4% (6,715)  20.7% (116)    0% (0)         0% (8)
Area
% of retraps (sample size)  
B
o
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y 
m
as
s 
(m
ea
n
 ±
 9
5 
C
I)
14
12
10
8
6
4
2
0
St
o
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ve
r 
(m
ea
n
 ±
 9
5 
C
I)
 Fat score                     Body mass
 Not retrapped                    Retrapped (1st capture) 
  Stopover duration         Retrapped (last capture)
100 Spring migration in the western Mediterranean and NW Africa
Figure 6. Temporal 
variation of third primary 
length according to area.
Figure 7. Temporal 
variation of physical 
condition according  
to area.
                                            March                             April                           May
    13    14   15    16    17    18    19    20    21    22    23    24    25    26    27   28    29    30
Pentad  
     Catalonia       Columbrets         Balearic Is (dry)             Balearic Is (wet)
     Chafarinas      N Morocco         S Morocco
 T
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 p
ri
m
ar
y 
le
n
g
th
 (
m
m
) 
 
Ph
ys
ic
al
 c
o
n
d
it
io
n
57
56.5
56
55.5
55
54.5
54
53.5
53
52.5
52
51.5 
                                           March                          April                                May 
  13    14   15    16    17    18    19    20    21    22    23    24    25    26    27   28    29    30
Pentad  
     Catalonia       Columbrets        Balearic Is (dry)           Balearic Is (wet)
     Chafarinas      N Morocco       S Morocco  
0.34
0.32
0.3
0.28
0.26
0.24
Catalonia                      Columbrets     Balearic Is. (dry)        Balearic Is. (wet)
Chafarinas                N M rocco     S Morocco
Catalonia                      Columbrets     Balearic Is. (dry)        Balearic Is. (wet)
Chafarinas                     N Morocco     S Morocco
101European Robin
Figure 8. Temporal 
variation in body mass 
according to area.
Figure 9. Temporal 
variation in fat score 
according to area.
Fa
t 
sc
o
re
  
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
                                         March                         April                        May
    13    14   15    16    17    18    19    20    21    22    23    24    25    26    27   28    29    30
Pentad  
     Catalonia       Columbrets        Balearic Is (dry)            Balearic Is (wet)
     Chafarinas      N Morocco        S Morocco
B
o
d
y 
m
as
s 
(g
r)
19
18
17
16
15
14
13
  13    14   15    16    17    18    19    20    21    22    23    24    25    26    27   28    29    30
Pentad  
     Catalonia       Columbrets      Balearic Is (dry)         Balearic Is (wet)
     Chafarinas      N Morocco      S Morocco 
                                    March                         April                            May 
Catalonia                      Columbrets     Balearic Is. (dry)        Balearic Is. (wet)
Chafarinas                     N Morocco     S Morocco
Catalonia                      Columbrets     Balearic Is. (dry)        Balearic Is. (wet)
Chafarinas                     N Morocco     S Morocco


European Robin (Erithacus rubecula)

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Revistes Catalanes amb Accés Obert