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Long-term monitoring of an insular population of Barbary Falcon Falco peregrinus pelegrinoides

  • Grupo de Ornitología e Historia Natural de las islas Canarias
  • Grupo de Ornitología e Historia Natural de las islas Canarias
  • Grupo de Ornitología e Historia Natural de las islas Canarias

Abstract and Figures

Territory spacing and breeding rates of an insular population (north-western Tenerife, Canary Islands) of Barbary Falcon Falco peregrinus pelegrinoides was studied from 1993 to 2008. The population increased constantly since the outset, from two pairs in 1993 to 12 in 2008. Mean density was 5.48 pairs per 100 km and mean nearest neighbour distance was 3 119 m. The regularity of the spatial distribution pattern of the nests, observed in most years, may be maintained in the future despite the expectation that new pairs may occupy still-vacant territories. Considering the 79 breeding attempts analysed, the mean number of fledged young per territorial pair was 1.92, per laying pair was 2.0 (n = 76), and per successful pair was 2.24 (n = 68). No significant variations were observed between the annual mean number of fledged young per laying pair, nor between the number of fledged young of pairs according to density in a 5 km radius. All fledglings (brood size one to four) left the nest in the month of May. In order to avoid affecting breeding success, sporting activities practised in the breeding areas must be correctly managed by the appropriate authorities.
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OSTRICH 2011, 82(3): 225–230
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doi: 10.2989/00306525.2011.629435
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Long-term monitoring of an insular population of Barbary Falcon
Falco peregrinus pelegrinoides
Manuel Siverio
*, Felipe Siverio
, Beneharo Rodríguez
and Airam Rodríguez
Constitución 17-3, E-38410 Los Realejos, Tenerife, Canary Islands, Spain
Los Barros 21, E-38420 Los Realejos, Tenerife, Canary Islands, Spain
La Malecita s/n, E-38480 Buenavista del Norte, Tenerife, Canary Islands, Spain
Department of Evolutionary Ecology, Estación Biológica de Doñana, CSIC, Avda. Américo Vespucio s/n, E-41092 Seville, Spain
* Corresponding author, e-mail:
Territory spacing and breeding rates of an insular population (north-western Tenerife, Canary Islands) of Barbary Falcon
Falco peregrinus pelegrinoides was studied from 1993 to 2008. The population increased constantly since the outset, from
two pairs in 1993 to 12 in 2008. Mean density was 5.48 pairs per 100 km² and mean nearest neighbour distance was
3 119 m. The regularity of the spatial distribution pattern of the nests, observed in most years, may be maintained in the future
despite the expectation that new pairs may occupy still-vacant territories. Considering the 79 breeding attempts analysed, the
mean number of fledged young per territorial pair was 1.92, per laying pair was 2.0 (n = 76), and per successful pair was 2.24
(n = 68). No significant variations were observed between the annual mean number of fledged young per laying pair, nor
between the number of fledged young of pairs according to density in a 5 km radius. All fledglings (brood size one to four) left
the nest in the month of May. In order to avoid affecting breeding success, sporting activities practised in the breeding areas
must be correctly managed by the appropriate authorities.
The taxonomic status of the Barbary Falcon is still
not entirely clear, since it has been regarded both as
a subspecies of Peregrine Falcon (Falco peregrinus
pelegrinoides; Del Hoyo et al. 1994) and as a distinct
species (F. pelegrinoides; Cramp and Simmons 1980,
Ferguson-Lees and Christie 2001). With few exceptions,
resident falcons in the Canary Islands show Barbary
phenotypes (Delgado et al. 1999, Rodríguez et al. 2011).
A preliminary genetic study, in which three falcons from
the Canary Islands with Barbary phenotypes were used,
showed hybridisation with Peregrine Falcon F. p. brookei,
as two of these bird samples had identical haplotypes to
the latter (Amengual et al. 1996). Other preliminary studies
show a very close genetic relationship between Barbary
Falcon and Peregrine Falcon, which indicates that the
former ‘represents a subspecies rather than a true species’
(Wink and Seibold 1996, Wink et al. 2000).
Mainly as a consequence of the use of dichlorodiphenyl-
trichloroethane (DDT) and derivatives, populations of
Peregrine Falcon from different geographical areas
decreased dramatically during the 1950s and 1960s (Cade
et al. 1988, Ratcliffe 1993). After the prohibition of organo-
chlorated pesticides and with increased legal protection, the
greater part of those populations has gradually recovered
naturally or by means of reintroduction programmes
(Castellanos et al. 1997, Horne and Fielding 2002, Powell
et al. 2002, Dzialak et al. 2005, Sielicki and Mizera 2009).
Although the precise causes are unknown, the falcons in
the Canary Islands were rarely seen at least from the
1950s to mid-1990s (Rodríguez et al. 2009). Indeed, in a
census carried out in 1987 and 1988 only seven pairs were
observed, and their distribution was limited to the eastern
islands and islets of this archipelago: Fuerteventura,
Lanzarote, Alegranza and Montaña Clara (Hernández et
al. 1991). Falcons are currently present on all the islands
and the number of pairs has been estimated to be about
144 (Siverio et al. 2009). Their presence on the island
of Tenerife has been known since the beginning of the
twentieth century (Thanner 1909), but the uncertainty
surrounding subsequent sightings led to their being consid-
ered extinct for many years (Hernández et al. 1991). Once
nesting was confirmed in 1991 (Hernández et al. 1992),
their numbers have increased until the present day, and 35
pairs is the latest population estimate for the entire area of
the island (Rodríguez et al. 2009).
In general, the density and breeding parameters of
many subspecies of Peregrine Falcon have been studied
in depth (Mearns and Newton 1988, Mendelsohn 1988,
Ratcliffe 1993,
Zuberogoitia et al. 2002, Rizzolli et al. 2005,
Verdejo and López-López 2008). With the exception of the
Canaries, where their biology and ecology have received
some attention (Delgado et al. 1999, Rodríguez and Siverio
2006, Rodríguez et al. 2007), the acquired knowledge of the
Barbary Falcon throughout its distribution range is still scant
(Ferguson-Lees and Christie 2001). In this regard, many of
the data available regarding Morocco, its area of occupa-
tion closest to the Canaries, are confusing since they could
also pertain to other sympatric races of Peregrine Falcon
Siverio, Siverio, Rodríguez and Rodríguez226
(Thévenot et al. 2003). In the present study we assess the
evolution of demographic and reproductive parameters in
an increasing Barbary Falcon population during 16 years.
Our main goals are to describe annual variation in density,
nest spacing and breeding rates, and evaluate the effect of
density on breeding performance.
Study area
Our study area is situated in the north-west sector of
Tenerife, the highest (3 718 m) and largest (2 034 km
island of the Canarian archipelago, located some 100 km
off the north-west coast of Africa (Figure 1). This zone is a
very steep massif known as Teno, of which around 105 km²
have been studied (taking into account its coastal platforms)
within an altitude range of 0–1 350 m. The south-west
flank is characterised by the presence of a great sea cliff
(c. 12 km long and with several sectors almost 500 m high)
cut by a succession of perpendicular deep ravines. One of
the best-preserved laurel forests in Tenerife is to be found in
the middle altitude zones of the northern flanks. The human
population of the area is estimated at 10 770 inhabitants
(, distributed in villages (inland valleys)
and towns (particularly on the coastal platforms). A good
part of this surface area is included in the Canarian Network
of Protected Natural Areas (Government of the Canary
Islands): Parque Rural de Teno (80.63 km²) and Sitio de
Interés Científico de Interián (1.01 km
During the breeding season (February–May) from 1993 to
2008 the previously occupied territories of Barbary Falcon
were visited, in addition to potential breeding sites (all the
cliffs of the Teno massif, both coastal and inland, were
inspected). It was assumed that a territory was being
occupied when the birds frequently used perching sites,
courting behaviour was observed, or, in the majority of
cases, when the nest was located. In order to assess
breeding rates, nest surveillance was performed with
telescopes (20–60×) and binoculars at distances ranging
from 250 to 600 m. In order to estimate the distances to the
nearest neighbours a global positioning system receptor
and a geographic information system (ArcView 3.2) were
used. On those occasions when their position could not be
established, because of the difficult orographic conditions,
the point on the breeding cliff where the behaviour of the
birds pointed clearly to the existence of a nest (nestlings
calling, adults bringing prey and newly fledged young) was
taken into account. The age of breeding birds (adults or
young of 2 cy) and the sex of the fledglings were determined
by means of the coloration patterns and size, respectively
(Ferguson-Lees and Christie 2001).
In order to avoid bias in the reproductive parameters,
breeding pairs were closely monitored from an early date
(February), to determine which pairs laid eggs (taking turns
during incubation) or which failed. To define the reproduc-
tive parameters we consulted Steenhof and Newton (2007).
The population growth rate was calculated by means of the
formula r = Ln (N
)/t, where N
is the final number of pairs,
the initial number of pairs, and t is the number of years
elapsed. The annual rate of multiplication was estimated with
the formula
= e
, affording the annual growth rate (%) as
1) × 100. The regularity of the spatial distribution of the
nesting sites was analysed by mean of the G-statistic (based
on the geometric mean/arithmetic mean ratio of the squared
distances between nearest nests), whose range of values
varies between 0 and 1, and would indicate a regular nest
spacing if it is greater than 0.65 (Brown 1975). To assess
the possible repercussion of pair density on reproduc-
tion, we have examined annually the size of the broods as
a function of the number of neighbour pairs (0, 1, 2, 3 and
4–5) in a radius of 5 km. The said surface area was chosen
after weighing up the mean distances and ranges between
neighbouring nests, both of Peregrine Falcon (Ratcliffe 1993,
Gainzarain et al. 2000, Zuberogoitia et al. 2002) and Barbary
Falcon in our study area. The data were analysed by means
of the Kruskal-Wallis non-parametric test and the chi-squared
test (Sokal and Rohlf 1981). The mean values are followed
by the standard error (±SE).
The population increased from two pairs in 1993 to 12
in 2008 (r = 0.119,
= 12.7%; Figure 2a). Four out of 10
15° W
28° N
Canary Islands
La Palma
La Gomera
El Hierro
Gran Canaria
100 km
Ten er i fe
study area
Figure 1: Map of the Canarian archipelago showing the study area
for Barbary Falcon on the island of Tenerife
Ostrich 2011, 82(3): 225–230 227
new territories were occupied by young females. Their
subsequent mating, once adulthood was reached, involved
one adult and three young males. In another territory, also
occupied for the first time, the pair consisted of an adult
female and a young male. Birds of the remaining territo-
ries (63.6%) were adults. Moreover, a paired adult male
was replaced by a young male approximately one year after
disappearing from the territory.
Mean density for the entire study period was
5.48 ± 0.64 pairs per 100 km
(range 1.90–11.43). Mean
distance between nearest-neighbour nests varied signifi-
cantly between years (H
= 50.81, p < 0.001; Figure 2b) and
the overall mean was 3 119 ± 332 m (n = 16). In most years
(n = 12) the spatial distribution pattern was regular (Figure 2c).
The number of nests recorded per territory fluctuated between
one and five (mean 2.27 ± 0.38). In those territories with more
than one nest, these were always very closely placed on the
same rock face (<200 m), with the exceptions of six over
1 000 m distant from the last nest used.
Reproductive parameters
Reproductive parameters were analysed using 79 breeding
attempts. Taken together, 152 chicks fledged the nest,
the mean number of fledged young per territorial pair was
1.92 ± 0.12, that per laying pair was 2.0 ± 0.12 (n = 76),
and that per successful pair was 2.24 ± 0.10 (n = 68). The
nesting success (proportion of laying pairs that raise at least
one young) was 89.5%. Mean annual productivity (number
of fledged young/laying pairs) did not vary significantly
between years (H
= 20.55, p > 0.05; Figure 2d), and no
differences were observed between productivity of pairs
with 0, 1, 2, 3 and 4–5 neighbouring territories in a radius
of 5 km (H
= 5.792, p > 0.05). Two breeding attempts by
the mixed pairs (adult–young) proved successful, while the
remainder of these pairs (n = 3) did not lay eggs judging
by their behaviour. The breeding success observed in 74
breeding attempts of adult pairs was 89.2% (n = 66). All
the fledglings that left the nest did so during the month of
May, and the brood size varied between one and four: 14
(20.6%) had one fledging, 27 (39.7%) had two, 24 (35.3%)
had three, and three (4.4%) had four. Fledging sex could
be determined in 49 individuals belonging to 22 broods, of
which 61.2% were male (
= 12, p < 0.01).
In the mid-1980s, none of the present territories of the
study area was occupied (FS and MS pers. obs.), and the
scant sightings of falcons both in the remainder of Tenerife
and in other western islands of the Canarian archipelago
were sketchy (Hernández et al. 1991). After the lack of
information since the beginning of the last century (see
Introduction), the first reliable observations of Barbary
Falcons in Tenerife took place relatively frequently during
1989/90 at Teno (Rodríguez et al. 2009), where two pairs
were confirmed to have bred one year later (Hernández et
al. 1992). All the above points to a recolonisation of Teno
(and, by extension, of Tenerife also), beginning in the years
immediately preceding the study period, probably from the
eastern Canaries (Siverio and Concepción 2004) or from
north-west Africa. This apparent expansion, which began
likewise to be observed in the remaining central and western
islands (Delgado et al. 1999), might have also taken place
7 000
6 000
5 000
4 000
3 000
2 000
Figure 2: Annual variation (1993–2008) in (a) number of pairs,
(b) mean distance between neighbouring nests, (c) spatial distribution
pattern, and (d) mean productivity of the Barbary Falcon population at
Teno Massif (Tenerife), Canary Islands. Productivity was calculated as
the number of fledged young per laying pair (the annual sample size
does not refer to the total of pairs, but pairs that could be monitored)
Siverio, Siverio, Rodríguez and Rodríguez228
from North Africa towards the Sahel, where observations of
the birds have continued to increase (Brouwer and Mullié
2000). The huge population increase in our study area, as in
the Canary Islands in general (Siverio et al. 2009), could be
because of coincidence of several factors including, among
others, legal protection of the species and high availability of
food resources (nowadays, feral pigeons constitute a plague
in many natural sites of the islands; MS pers. obs.).
If population dynamics during the Teno study are taken
into account, the cases of young territorial females and
mixed pairs (adult–young) detected can not be taken to
indicate a negative tendency (e.g. replacement of birds
induced by human persecution), as reported for stable
populations of falcons and other birds of prey (Ferrer et al.
2003, Pandolfi et al. 2004). On the contrary, our examples
(sighted throughout the monitoring period) appear to be
more related to population growth in an enclave with a high
load capacity, where the young produced occupy optimal
vacant sites, at times on an individual basis (females). On
the other hand, the use of new nests within a territory could
not be attributed to substitutions of breeding females (see
Zuberogoitia et al. 2002 for the Peregrine Falcon) owing to
the fact that the birds were unmarked.
For the entire island of Tenerife, Rodríguez et al. (2007)
found a density of 1.27 pairs 100 km
and a mean distance
between neighbouring nests of 5 868 m. In this study, the
importance of Teno is already noteworthy (given the high
availability of suitable cliffs and other factors) as being one
of the areas of the island with a greater density of Barbary
Falcon. Thus, the availability of these cliffs favours the
abundance of falcons and other rupicolous species, both
here (Rodríguez et al. 2007, Siverio et al. 2007, Rodríguez
et al. 2010, present study) and in continental environments
(Newton 1988, Gainzarain et al. 2000, Jenkins and van Zyl
2005, Rizzolli et al. 2005). On the other hand, annual differ-
ences in distances between neighbouring nests detected
in Teno are because they were greater when there were
fewer pairs at the beginning of the study. When their
number subsequently increased, the abundance of trophic
resources may have minimised intraspecific conflicts and,
consequently, favoured the regularity of the spatial distribu-
tion pattern recorded in most years (see e.g. Solonen 1993).
On the other hand, the irregularity of the spatial distribution
pattern observed between 2005 and 2007 (Figure 2c) was
caused by a new pair established at a much greater than
average distance (>5 000 m). Considering that Teno still
offers potential nesting territories, it is foreseeable that the
population will continue to increase and when it stabilises
(c. 15 pairs) spatial regularity will be maintained. Indeed,
in the Italian Alps, the spacing of a stable population of
Peregrine Falcon was always regular in each of the six
years studied (Rizzolli et al. 2005), although in the Cape
Peninsula (South Africa) observed spacing was irregular,
probably because of the equally irregular distribution of cliff
sites (Jenkins and van Zyl 2005).
Breeding parameters
The values of the breeding parameters of our study are within
the range of those recorded in populations of Peregrine
Falcon (see reviews in Zuberogoitia et al. 2002, Rizzolli et
al. 2005). For F. p. babylonicus, a very similar race to that
dealt with here, the scant data published give the most
usual brood size as two (Dementiev 1957). According to
the available information on the few populations of Barbary
Falcon monitored, particularly in the Canaries, no disparity is
observed between the mean values found in the islands and
those of the study area (Table 1). The sole exception is the
considerably higher value of the Teno fledging rate (fledged
young/successful pairs) versus that of the island of Tenerife
(Teno included), which may well be caused by a greater
sample in the former case (Table 1).
It is highly probable that the very scant rainfall in our
study area (mean values for March–April, 2000–2008:
37.68 ± 6.5 mm, range 11.2–74.8; http://www.agrocabildo.
com) does not limit productivity, as occurs in other regions
where rainfall is abundant (Mearns and Newton 1988, Olsen
and Olsen 1989, Zuberogoitia et al. 2002). Moreover, if we
consider that a great number of nest sites in Teno are on
cliff ledges under an overhang and in cavities (MS pers.
obs.), the absence of differences between years is not
surprising. A further factor limiting productivity in birds of
prey is the availability of prey species (Newton 1979). In
our study area, both wild and feral pigeons Columba livia
are abundant and may represent a substantial contribu-
tion to the diet during chick rearing (93.3%, n = 45 nest
prey delivery observations). It is noteworthy that in some
populations of Peregrine Falcon the continuous availability
of large prey, such as pigeons, implies high productivity
(López-López et al. 2009).
In birds of prey, population increase can also involve
decreased productivity, as the new pairs occupy lower-
quality territories (presence and absence of floating popula-
tion, trophic resources, etc.), and narrowing of territories
(Ferrer and Donázar 1996, Carrete et al 2006). However,
in Teno, even taking into account the gradual decrease
in distance between neighbour territories (Figure 2c),
the good quality of territories could minimise the density-
dependent effect on productivity. The causes of breeding
failure (10.5%) may have been related to the disappear-
ance of a male during incubation, the apparent nest robbing
or depredation of a brood at early-stage and the probable
infertility of the eggs of six clutches (incubation was verified,
but no chicks were subsequently observed).
Both the information contained in the present study and
that provided by Rodríguez et al. (2007) and Delgado et
al. (1999) for all of Tenerife and the archipelago, respec-
tively, provide evidence that Teno is one of the best areas
for Barbary Falcon in the Canaries. Despite the fact that
its population has, in general, increased in the Canarian
archipelago (Rodríguez et al. 2009), its conservation
status (IUCN criteria) remains Endangered (Siverio and
Concepción 2004). The greater part of the territories are
located in Protected Natural Areas of the Canary Islands,
and it is thus improbable that its nesting habitat will be
significantly modified, at least in the short and medium
term. Despìte all the above, many people practise outdoor
sports such as rock climbing, abseiling, and hang-gliding
in Teno and other sites, implying a potential risk for the
falcons, as well as other birds of prey, during the breeding
season. Indeed, it is known that the productivity of the
Ostrich 2011, 82(3): 225–230 229
Peregrine Falcon is lower in nests situated on rock faces
where climbing is practised, unlike sites that remain
undisturbed by such activity (Brambilla et al. 2004). On the
other hand, since the Barbary Falcon population began to
increase in Teno and in the Canaries in general, problems
have arisen between certain pigeon fanciers (because of
pigeon capture) and hunters (for alleged disloyal competi-
tion) on the one hand, and the appropriate authorities on the
other. Although such conflicts should be resolved, the most
pressing issue at present is the efficient management by the
relevant authorities of the above-mentioned sporting activi-
ties where necessary. Likewise, before implementation of
conservation measures such as modifying the legal conser-
vation status of the species, we recommend a census be
undertaken of the entire Canarian archipelago in order to
assess the current status correctly.
Acknowledgements — All expenses incurred during this study
were defrayed by the authors. We thank Pauline Agnew and Luis
Cadahía for assisting with the English translation, Francisco M
González for logistic support, and Pilar Bello for preparing Figure
1. Thanks are also due to Iñigo Zuberogoitia for his critical review
of the initial manuscript, and two anonymous referees for their
valuable comments and corrections.
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Mean number of fledging young per pair
Territorial pair Laying pair Successful pair
Morocco 2.30 (10; ?) Thévenot et al. (2003)
Lanzarote 2.53 (54; 7) 2.48 (37; 5) Delgado et al. (1999)
Tenerife 1.55 (37; 2) 1.76 (30; 2) Rodríguez et al. (2007)
Teno 1.92 (79; 16) 2.00 (76; 16) 2.24 (68; 16) This study
Table 1: Productivity estimates for populations of the Barbary Falcon across its distribution range. Sample size is shown in brackets followed
by the number of years monitored
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Received July 2010, accepted August 2011
Editor: M Virani
... With the exception of a few studies carried out on the Canary Islands regarding its breeding biology and habitat selection (Rodríguez & Siverio 2006Siverio et al. 2011, Rodríguez et al. 2018a, basic knowledge of the biology and ecology of the Barbary Falcon is still scarce throughout its range (Ferguson-Lees & Christie 2001, White et al. 2013. This falcon is a bird-feeding specialist that usually breeds on the highest available cliffs; many aspects of its behaviour and life history traits seem to be generally similar to those of other well-known peregrine subspecies (see Ratcliffe 1993, Ferguson-Lees & Christie 2001, White et al. 2013. ...
... raising at least one fledging) exceeds 80%. Its mean productivity (mean number of fledging per territorial pairs) estimated for some islands and years varies between 1.62 and 2.53 (Delgado et al. 1999, 2018aSiverio et al. 2011). ...
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During 2015 and 2016, we conducted the first systematic study of the size of the breeding population, distribution, habitat and diet of the Barbary Falcon Falco peregrinus pelegrinoides on La Palma, Canary Islands. We found a minimum of 28 territories (3.9 territories/100 km2) at an average distance of 3.6 km (range 1.7–7.7 km) from their nearest neighbours. The territories were distributed throughout the island, but there were more in the northern half, probably due to a greater availability of large cliffs. Falcons selected high cliffs situated in scrub-covered areas close to the coast with relatively high levels of human infrastructures. However, this picture could be biased due to the inherent difficulties in surveying the rugged innermost parts of the island, where some territories may not have been detected. The nine monitored nests were situated in natural cavities or ledges at heights ranging from 35 to 110 m above ground level. Egg-laying probably takes place in late March, later than in the rest of the Canarian archipelago, perhaps due to the rainier climate of this island. On average, almost two chicks fledged per nest, a similar rate to nearby populations. Diet was composed of at least seven bird species, with Columba livia being the most frequently hunted and the most important prey item (93.9% of diet biomass). As falcons prey upon domestic racing pigeons (a popular activity on the island), direct persecution could be one of the main threats for the Barbary falcons on La Palma. There is a widespread but false idea that these raptors are not native, and that their presence is due to deliberate releases of foreign falcons by local government bodies. Thus, a human-wildlife conflict has arisen with pigeon fanciers whose solution requires more reliable information on the scale of the predation on pigeons and an environmental education campaign.
... Estos valores son más elevados que los obtenidos en otros lugares del archipiélago canario. Así por ejemplo en el Macizo de Teno se estimó en 1,92 y 2,00, la productividad (pollos volanderos/pareja activa) y la tasa de vuelo (pollos volanderos/pareja con éxito), respectivamente (SIVERIO et al., 2011), y para el conjunto de la isla de Tenerife estos valores son de 1,55 y 1,75 . Sin embargo, en particular la tasa de vuelo estimada en el Parque Nacional resulta ser algo más baja que la estimada para la isla de Lanzarote, cuya estimación alcanzó los 2,48 pollos volanderos/pareja con éxito (DELGADO et al., 1999). ...
... El promedio de las distancias mínimas entre territorios, medidas desde el nido, y considerando los ocho nidos mencionados anteriormente, fue de 3,70 + 2,90 km, variando entre 2,10 y 8,90 km. Esta distancia representativa del Parque Nacional de Timanfaya es considerablemente más pequeña que la de 5,8 km estimada para el conjunto de la isla de Tenerife o la de 5,2, en el caso de El Hierro (RODRÍGUEZ & SIVERIO, 2006), pero mayor que la de 3,1 km calculada para el macizo montañoso de Teno en el noroeste de Tenerife (SIVERIO et al., 2011). ...
Technical Report
Situación y problemática de las poblaciones de rapaces en el P.N. de Timanfaya
... Buzzards' data correspond to the 2007 season (Rodríguez et al. 2010b), and for the most abundant species, the common kestrels, nest locations were obtained during 2005-2010 given that the most remote and rugged sectors were surveyed at least 1 year to cover all available habitats for this species. We are aware that raptor density may strongly fluctuate among years due to variability in climate or feeding resources (Newton 1979), but prey availability and climatic stability in the Canary Islands produce no large annual variation in raptor breeding densities (see Siverio 2006;Siverio et al. 2007;Rodríguez et al. 2010b;Siverio et al. 2010a). We may have missed a few nest sites, especially of the abundant kestrels, but we are confident that such omissions represent less than 5% of total nesting sites. ...
... Our results highlight the high conservation value of Teno for birds of prey. It is a very important stronghold for the threatened studied raptors: 1) the unique ospreys breeding pairs of the island, which constitute more than 30% of the Canarian breeding population, are bound to the Teno coastal cliffs (Rodríguez et al. 2013); 2) the first Barbary falcon breeding pairs of Tenerife were discovered on Teno in the early 1990s, since then the insular population has spread through the island reaching more than 35 pairs at present (31% of them breeding in Teno; Siverio et al. 2009Siverio et al. , 2010a; 3) the common raven was formerly distributed through the island, but during the last four decades it has suffered a sharp decline and the bulk of the breeding insular population survived restricted to Teno (Lorenzo 2007;Siverio et al. 2007). In addition, many endemic plants and invertebrates occur there (Reyes-Betancort et al. 2008;Martín 2010), and some vertebrates maintain their more important or unique insular breeding populations there, such as for example the Canarian spotted lizard Gallotia intermedia, the Manx shearwater Puffinus puffinus, or the rock sparrow Petronia petronia (Rodríguez et al. 2014). ...
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The specific spatial distribution and habitat association -strongly influenced by environmental factors or competitive interactions- are major issues in ecology and conservation. We located and georeferenced nesting sites of five cliff-nesting raptors (Egyptian vulture Neophron percnopterus, common buzzard Buteo buteo, osprey Pandion haliaetus, common kestrel Falco tinnunculus, Barbary falcon Falco peregrinus pelegrinoides), and common raven Corvus corax on one of the most biodiverse hotspot within the Canary Islands (Teno, Tenerife). We used generalised linear models to evaluate the factors affecting abundance, richness and intra- and interspecific interactions. Raptor abundance increased with slope, shrub-covered area, and habitat diversity, and decreased with altitude, and forested and grassed areas. Richness increased with slope and decreased with altitude. Threatened species (osprey, Barbary falcon and raven) occupied cliffs farther away from houses and roads, and more rugged areas than the non-threatened species. The models suggested that the probability of cliff occupation by buzzards, falcons and ravens depended only on inter-specific interactions. Buzzard occupation increased with the distance to the nearest raven and kestrel nests, whereas falcons and ravens seek proximity to each other. Teno holds between 75-100% of the insular breeding populations of the most endangered species (osprey and raven), indicating the high conservation value of this area. Our study suggests that the preservation of rugged terrains and areas of low human pressure are key factors for raptor conservation and provide basic knowledge on the community structure and habitat associations to develop appropriated management actions for these fragile island populations.
... The habitat and breeding biology of the peregrine falcon are well known in many world regions (olSen, olSen 1988, gainzarain et al. 2000, JenkinS 2000, enderSon et al. 2012. However, knowledge about the natural history of the Barbary falcon is lacking throughout its range, except for the Canary Islands where both the habitat and the reproductive rates have been studied (rodríguez, Siverio 2006, rodríguez et al. 2007, Siverio et al. 2011) and the population is estimated to 143 pairs (Siverio et al. 2009). In fact, apart from general summaries on the bird's status (evanS et al. 2005), the very few studies from the Middle East have been focused mainly on the distribution of local populations (SCott et al. 1975, Shirihai 1996, khaelghizadeh et al. 2011, their foraging pattern (YoSeF et al. 2011) anddiet (ShaFaeipour 2014). ...
... We found one of the highest average productivity ever recorded for the peregrine falcon (see zuberogoitia et al. 2002, rizzoli et al. 2005). The mean productivity of Barbary falcons in a high quality area of Tenerife (Canary Islands) was also much lower (1.92 fledged young; Siverio et al. 2011). Generally, productivity in raptors may depend on factors such as density (Carrete et al. 2006(Carrete et al. , bretagnolle et al. 2008, rainy days (zuberogoitia et al. 2013(zuberogoitia et al. , anCtil et al. 2014, the prey size (lópez-lópez et al. 2009) and individual qualities (zabala, zuberogoitia 2014). ...
Full-text available
Both ecology and biology of the peregrine falcon are well known throughout its range. However, excepting the data from the Canary Islands, knowledge on the Barbary falcon natural history is scarce. We studied four Barbary falcon nesting sites in South-western Iran between 2011 and 2014. All eyries were located in cavities of cliffs whose average height was 80 m, on average just over 1 km away from roads and villages. Although sample size was small (n = 7 clutches), the mean clutch size (four eggs) and productivity (3.43 fledglings) per eyrie reached the highest values recorded for peregrine falcons.
... So far, only individual islands or archipelagos in the Mediterranean or elsewhere have been investigated (e.g. Amori, Rizzo Pinna, Sammur, & Luiselli, 2015;Guerra, García, & Alcover, 2014;Siverio, Siverio, Rodríguez, & Rodríguez, 2010). ...
Aim: Following the classical MacArthur-Wilson island equilibrium model of species richness, we hypothesize that island size and isolation affect prey composition and diet diversity of predators on islands. We used the barn owl as a model predatory organism that is known for feeding and habitat flexibility and explored the patterns of its diet on Mediterranean islands in relation to the island biogeography and human population density. Location: Mediterranean Islands. Taxon: Barn owl (Tyto alba) and its prey. Methods: Data on taxonomic composition of the barn owl diet were obtained from pellets (Adriatic island of Korčula) and from published studies performed on 18 Mediterranean islands. For each island, diet diversity indices were calculated and correlated with island area, linear distance from the mainland, human population size and density, and geospatial trends. Results: Murinae mice and rats were the dominant prey. The proportion of birds and reptiles consumed was 5 and 18 times higher, respectively, than in Europe in general. Diet diversity correlated with island size, but not island isolation. Island size was also a good predicator of the proportions of the vertebrate prey. Human population density and longitude had no effect on diet diversity. Main conclusions: Diet diversity of the barn owl on Mediterranean islands only partly followed the island biogeography theory. Diet diversity was greater on the larger Mediterranean islands. However, a more diverse diet did not mean a higher number of taxa, but a wider range of abundant and evenly represented taxa. The smaller the islands, the more birds and reptiles were consumed, compared to higher proportions of mammals on the larger islands. These findings support the idea of barn owls’ feeding flexibility and opportunistic predator behaviour. Despite the barn owl being a synanthropic bird, urbanization had no influence on its diet diversity. Also island isolation had no significant effect.
Technical Report
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Se ha querido integrar la información disponible sobre el uso de los UAS como herramienta de conservación e investigación y los efectos nocivos documentados sobre la avifauna. Conociendo las ventajas y desventajas , y estableciendo como referencia el principio de precaución, se establecen una serie de recomendaciones para volar con seguridad. Con estos objetivos queremos evitar que, en el futuro, los UAS se conviertan en una amenaza para la biodiversidad del P.N. de Timanfaya. We wanted to integrate the available information on the use of UAS as a conservation and research tool and the documented harmful effects on the birdlife. Knowing the advantages and disadvantages and establishing the precautionary principle as a reference, a series of recommendations are established to fly safely. With these objectives, in the future, we want to prevent the UAS from becoming a threat to the biodiversity of the Timanfaya National Park .
Technical Report
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Asistencia técnica financiada por el Cabildo Insular de La Palma.
Peregrine Falcons (Falco peregrinus) on the Canary Islands are considered to be of the Barbary Falcon subspecies (F. p. pelegrinoides). Here we report on lost falconry birds present among the wild population of resident falcons, and provide rough approximations of their abundance for Tenerife, the largest island of the Canaries. We observed lost falconry birds breeding with natural wild falcons, with at least one mixed pair producing fledglings. Only 54.1% of the breeding adults that we studied on the island showed typical Barbary Falcon plumage. Some nest sites were systematically poached, affecting the overall productivity of the population. Our findings suggest that the original Canarian Barbary Falcon population could be suffering from genetic mixing due to the presence of individuals originating from outside the population and from illegal harvest of nestlings. We recommend that local authorities continue to assess the degree of genetic admixture that occurs in this population, modify the current falconry regulations, implement management actions to prevent new escapes, eradicate exotic raptors, and put a stop to illegal nestling harvests.
We studied the post-fledging movement of two sibling (male and female) juvenile Barbary Falcons (Falco peregrinus pelegrinoides) hatched in Lanzarote (Canary Islands) in 2011 using satellite tracking. Birds were tracked from fledging in May to the end of November, when the signals of both transmitters were lost. During the first 45 d following fledging, both birds behaved similarly and made some flights <70 km away from their nest, on the island where they hatched. However, after the dependence period, we found differences between the individuals. The female made several inter-island movements among the islands of the central archipelago (Gran Canaria, Tenerife and La Gomera) and returned to Lanzarote in October. In contrast, the male stayed close to his natal nest (<100 km) until the end of October, when he was detected in the middle of the Atlantic Ocean >3000 km from the nest, probably using a ship as a perch. Because Barbary Falcon populations of the Canary Islands are listed as "threatened" due to anthropogenic threats (e.g. collisions with human-made structures, illegal shooting, nest-robbing, and hybridization with escaped falconry falcons) and little is known about their post-fledging dispersal movements, more studies of such life-history characteristics, using ringing and remote sensing, are urgently needed to develop management actions for their conservation.
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We report on a 32—yr study of a population of Spanish Imperial Eagles, Aquila adalberti, which increased during the first 16 yr of study but remained stable during the last 16 yr. We analyzed changes in the mean and variance of fecundity in relation to population density to test predictions of two hypotheses of density—dependent fecundity. According to the interference" hypothesis, as density increases, frequency of agonistic encounters increases, resulting in a relatively uniform decrease in habitat quality. Consequently, mean fecundity decreases, and no relationship is expected between density and variance in fecundity. For the habitat heterogeneity hypothesis, however, as density increases, a greater proportion of individuals are forced to occupy lower quality habitats. Thus, mean fecundity decreases and fecundity variance must increase. Additionally, for this hypothesis, fecundities in good sites are expected to be equal in both low— and high—density situations. An inverse relationship between fecundity and population size was found in this eagle population. Annual variance in productivity showed significant increases over the study period. This trend was inversely related to mean productivity. Variance in productivity was related to the year of pair establishment, being higher in recently occupied territories. Mean and variance of the longer term territories remained constant during the study period. These results are in accordance with the habitat heterogeneity hypothesis.
We monitored 38 juvenile Peregrine Falcons (Falco peregrinus) up to 3 mo immediately after their release from a hack box during 1999-2000. The restoration site was a cliff near Eagle Point Park in Dubuque, Iowa. Falcons were released in a staggered manner from mid-June until late July each summer. Older falcons remained at the site longer than at previous urban releases and interacted with the younger falcons. The four mortalities (11%) confirmed during the observation periods were discovered and reported by citizens near the release site. We used radiotelemetry, observations of color-marked birds at the hack site, and recovered mortalities to estimate weekly survival rates and dispcrsal patterns. We estimated weekly survival rate to be 0.988 (SE = 0.01), and our weekly resighting rate was high: 0.885 (SE = 0.03). juveniles were observed for an average of 4.3 wk in 1999 (SD = 2.5), but only 3.4 wk in 2000 (SD = 2.3). Accordingly, weekly fidelity rates were year-specific: 0.903 (SE = 0.03) in 1999 and 0.795 (SE = 0.05) in 2000. No mortalities were attributed to Great-horned Owl (Bubo virginianus) predation, but substantial numbers of owls were seen in summer 2000. The presence of owls in 2000 may have contributed to the difference in fidelity rates and dispersal patterns between years.
(1) During 1974-82, peregrines in south Scotland produced an annual average of 1.15 young per territorial pair, between 0.60 and 1.45 in different years. Heavy rain in May lowered productivity, by reducing hunting success and by soaking exposed nests. Early clutches, begun before mid-April, were larger and more successful than later ones. (2) All pairs nested on cliffs; the few large cliffs were preferred, so that, as the population grew, more pairs used small cliffs. Cliff height and accessibility to human climbers greatly influenced nesting success, as did exposure. Those nests in recesses were most successful. (3) Performance improved as females aged; laying became progressively earlier and clutches progressively larger, from 1 to 5+ years. (4) Despite some slight eggshell thinning (attributed to DDE), organochlorine residues had at most a small impact on productivity in the years concerned (in contrast to earlier years). (5) The overall density of breeding peregrines more than doubled during the 9-year study, and also varied between different parts of the study area. But over the range of densities observed, no density-dependent depression of breeding success occurred.
The central west coast of the Baja California peninsula was an important Peregrine Falcon (Falco peregrinus) breeding area supporting a population of about 13 breeding pairs. This population declined drastically during the 1960s and early 1970s. We conducted field surveys and compiled data on nesting Peregrine pairs from 1980-94 to address the current status of the Baja population. We found 10 pairs nesting in the area indicating the Peregrine population has recovered in the area since the late 1970s. Due to increased human activity in the area, proper management is needed to provide suitable nesting sites and to minimize human disturbances during the nesting season.