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The role of pigeon consumption in the population dynamics and breeding performance of a peregrine falcon (Falco peregrinus) population: Conservation implications

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In this paper, we describe and analyze the diet of peregrine falcons during a long-term period (1982–2002). A combination of direct observations of prey brought to nests, prey remains, and regurgitated pellets were used to calculate diet diversity and dietary overlap between peregrine pairs. We also examined diet diversity in relation to breeding performance. All peregrine pairs fed mainly on birds, with pigeons the most common prey. An increase in pigeon availability has been associated with both an increase in population size and an increase in breeding performance (measured as the average productivity of pairs per year) of a small peregrine falcon population in eastern Spain. Average productivity was lower when dietary breadth was higher. We speculate that our results were the synergistic effect of declining persecution and increased pigeon availability through increased popularity of keeping racing pigeons. There is a conflict of interests between pigeon fanciers and peregrine conservation. As a consequence, this could result to an increased risk of mortality by direct persecution. In accordance with this, conservation measures aimed at preventing direct persecution are encouraged.
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ORIGINAL PAPER
The role of pigeon consumption in the population dynamics
and breeding performance of a peregrine falcon
(Falco peregrinus) populatio n: conservation implications
Pascual López-López & José Verdejo & Emilio Barba
Received: 18 February 2008 /Revised: 7 August 2008 /Accepted: 16 September 2008 /Published online: 7 October 2008
#
Springer-Verlag 2008
Abstract In this paper, we describe and analyze the diet of
peregrine falcons during a long-term period (19822002).
A combination of direct observations of prey brought to
nests, prey remains, and regurgitated pellets were used to
calculate diet diversity and dietary overlap between
peregrine pairs. We also examined diet diversity in relation
to breeding performance. All peregrine pairs fed mainly on
birds, with pigeons the most common prey. An increase in
pigeon availability has been associated with both an
increase in population size and an increase in breeding
performance (measured as the average productivity of pairs
per year) of a small peregrine falcon population in eastern
Spain. Average productivity was lower when dietary
breadth was higher. We speculate that our resul ts were the
synergistic effect of declining persecution and increased
pigeon availability through increased popularity of keeping
racing pigeons. There is a conflict of interests between
pigeon fanciers and peregrine conservation. As a conse-
quence, this could result to an increased risk of mortality by
direct persecution. In accordance with this, conservation
measures aimed at preventing direct persecution are
encouraged.
Keywords Diet
.
Castellón
.
Homing
.
Pigeon fancying
.
Raptors
.
Spain
Introduction
The peregrine falcon Falco peregrinus is the most widely
distributed raptor. In the Mediterranean region, the subspecies
occurring is F.p. brookei (Cramp and Simmons 1980;Del
Hoyo et al. 1994). With a preferentially avian-based diet
(Ratcliffe 1993; Monneret 2000), there are several reported
cases of hunting on mammals, insects, and even fishes
(Zuberogoitia et al. 2002). Actually, its capacity to prey on
species of human interest has caused a traditional rejection by
some sectors of the society, especially those related with
human economic interest. In the Spanish Mediterranean
region, similar to other regions of Southern Europe, pigeon
fancying has become a traditional activity which is very
deep-routed, with its origins going back to the Muslim
occupation of Spain in the eight century (Mínguez et al.
2005). As peregrines can prey on racing pigeons, it gives rise
to a clear conflict of interest among pigeon fanciers and
peregrine conservation, especially accentuated with those
pairs located closer to human populated areas (Ratcliffe
1993; Dixon et al. 2003). Then, it is interesting to clearly
describe and analyze the diet of peregrines in such areas and
to implement reliable con servation measure s aimed at
preventing a potential conflict.
In this paper, we describe and analyze the diet of a small
population of peregrine falcons located at the East of Spain
combining the use of three methods: (1) direct observations
of prey brought to nests, (2) collection of prey remains, and
(3) collection of pellets during a long-term period. We
examine the effect of changes in the diet in relation to the
observed duplication of the population size. Furthermore,
Eur J Wildl Res (2009) 55:125132
DOI 10.1007/s10344-008-0227-2
Communicated by C. Gortazar
P. López-López (*)
:
E. Barba
Cavanilles Institute of Biodiversity and Evolutionary Biology.
Terrestrial Vertebrates Group, University of Valencia,
Polígono de la Coma s/n,
46980 Paterna, Valencia, Spain
e-mail: Pascual.Lopez@uv.es
J. Verdejo
Department of Microbiology and Ecology. Ecology Unit.
Facultad de Ciencias Biológicas, University of Valencia,
Campus de Burjassot. C/Doctor Moliner 50,
46100 Burjassot, Valencia, Spain
some descriptive parameters of dietary composition like
prey diversity, dietary breadth, and dietary overlap among
pairs are calculated. Additionally, we also examine diet
diversity in relation to breeding performance.
Materials and methods
Study area
The study area was loca ted in ea stern Spain, in the
southwest of Castellón province, including the Alto
Palancia and half of the Alto Mijares districts (40°08 N,
39°43 S, 0°26 E, 0°50 W; Fig. 1). This area encompasses
1,500 km
2
and ranges from 300 to 1,400 m a.s.l. and is
characterized as Mediterranean climate. For a complete
description of the study area, see Verdejo (1991, 1994) and
Verdejo and López-López (2008). The study was conduct ed
between 1982 and 2002 during each breeding season (from
early February to the end of July).
Numerous papers have tested different methods to assess
the diet in raptors (Martí 1987; Simmons et al. 1991) and
particularly in peregrine falcons (Oro and Tella 1995).
These methods include (1) direct observation of prey
hunting, (2) observation of prey contribution to the nest,
(3) collection of prey remains, and (4) collection of pellets
(the regurgitated, indigestible body parts of preys; Dekker
1980; Bird and Aubry 1982; Thiollay 1982). For this study,
we have employed the last three methods, given that the
combination of them has been sugges ted as a good estimate
of peregrines diet (Oro and Tella 1995).
For the detection of breeding pairs, direct searches for
nesting places were conducted, and all known breeding
places and potential ones were visited (Ratcliffe 1993).
Observations were made 300 m from cliff nest sites with a
2060× spotting scope during clear days to avoid disturbance
to falcons. A territory was considered occupied if we observed
nests with hollows, typical pair behavior, courtship, brood
rearing activity, or young (Newton 1979; Steenhof and
Kochert 1982). We considered as the same pair those that
occupied the same breeding place during all years or at least
one part of the study period, although presumably, some
individuals conforming breeding pairs could have changed.
Dietary data of at least 5 years for each pair was obtained,
except for one new pair settled in 2002 which only data for
this year were available, excluding them from the analysis.
Data on number of prey items recorded per pair, monitored
years, breeding performance (measured as average produc-
tivity per pair per year), distance to nearest neighbor, and
distance to nearest village were recorded for all the pairs in
the study area.
All nest sites and frequently used roosting places were
visited to collect pellets and abandoned prey remains during
the breeding season. In addition, in order to minimize the
bias of pellets and prey remains in the composition of the
peregrine diet, we also conducted direct observations of prey
contribution to the nests (Dekker 1980; Bird and Aubry
1982;Thiollay1982; Oro and Tella 1995). Data from the
three sources were pooled together for the analyses. It might
be possible that some minor duplication could have occurred
because the same prey item may have been recorded by each
of the three methods. At least three visits were made to each
pair during the breeding period, with an average duration of
240 min per visit. Prey items were identified to species level
by comparison to field guides and a private collection of
bones and feathers owned by the second author. In several
cases, principally in pellet analysis, prey identification to
species level was impossible, and data were grouped as a
single category named unidentified passerines.Thisgroup
was deducted in the sum of species richness for each pair.
Prey biomass was estimated according to Cramp et al.
(19771985) and Jutglar and Masó (1999).
Prey diversity
We calculated the Gini index of diversity (Gotelli and
Ellison 2004) instead of other commonly used indexes of
diversity (e.g., the ShannonWeiner index) because it does
not confound species richness and evenness and especially
because of its lack of dependence on sample size (Gotelli
and Graves 1996; review in Magurran 2003). This index is
used taxonomically at species level, and similarly to other
indexes, the higher the index value, the higher the diversity
measure (Gotelli and Graves 1996).
The index was calculated as:
G ¼ 1
X
n
i¼1
p
2
i
Fig. 1 Iberian Peninsula with the Castellón province shaded. In box:
Castellón province. The study area is shaded in gray
126 Eur J Wildl Res (2009) 55:125132
where p
2
i
is the square of the proportion of each prey item i
in the sample.
Dietary breadth
Dietary breadth allows measuring how diverse the peregrines
diet is. This is similar to the Gini prey diversity index, but in
this case, prey items are grouped by taxa higher than the
species level (family, order, etc.). Dietary breadth was
calculated following Steenhof and Kochert (1985)onthe
basis of the formula proposed by Levins (1968). According to
them, dietary breadth was calculated as:
B ¼ 1
.
X
p
2
i
where p
2
i
represents in this case the square of the proportion of
the diet contributed by the ith taxon. Values for this index
range from 1 to . For consistency, prey taxa were grouped
by family for birds and mammals and for order for reptiles,
allowing comparisons among pairs (Watson 1997). In both
prey diversity and dietary breadth indexes, unidentified
passerines were treated as a single category.
Dietary overlap
The dietary overlap among breeding pairs was calculated
by means of the Piankas overlap index (Pianka 1973). A
null model of dietary overlap was performed using the
niche overlap module of the freely available EcoSim v7.0
software (Gotelli and Graves 1996; Gotelli and Entsminger
2001, www.garyentsminger.com). It allowed us to test if the
observed dietary overlaps differ from that expected by
chance (Sale 1974;Schoener1974;IngerandColwell1977).
A randomization algorithm was performed retaining the
dietary breadth of each pair, but randomizing which
particular resource states was utilized. Following Lawlor
(1980), it would correspond to a randomization algorithm of
type 3, and it is especially recommended to study dietary
niche overlap when all resources are all potentially available
(in our case, it means that there is no biological constraints
preventing peregrines consumption from any class of prey;
Gotelli and Graves 1996). This index was used taxonomi-
cally at species level. A complete review of the advantages
and potential applications of this method are available in
Haefner (1988)andWinemillerandPianka(1990).
Pigeon availability
Pigeon availability was estimated by interviewing pigeon
fanciers of the municipalities included in study area. We
also obtained data from the Spanish National Institute of
Statistics (www.ine.es). Pigeons were classified as wild
birds (including Columba livia, C. oenas, C. palumbus,
Streptopelia decaocto, S. turtur), racing birds, strays (birds
that have been lost and not returned to lofts), and ferals
(birds that have been incorporated into the wild population).
We gathered information about number of pigeon fanciers
clubs, year of creation, initial and current number of pigeon
fancying licenses, and presence of pigeon barriers (pigeon
lofts built to prevent falcons and eagles from attacking racing
pigeons) in the vicinity of the nesting areas. The number of
flying days per week, number of flying pigeons per day, and
number of racing pigeons per competition were also
obtained.
Statistical analysis
Differences in diet composition among pairs were tested by
means of chi-square tests on contingency tables. Non-
parametric correlations were performed to examine the
effect of changes in the proportion of pigeon consumption
by year in relation to changes in the peregrine population
size and between the average productivity (calculated as
fledged chicks/ number of years of occupied territory) of
peregrines pairs and the percentage of pigeons in the diet.
In addition, to test how the diversity of their diet affects
peregrines breeding performance, a non-par ametric corre-
lation was performed between the average productivity and
the dietary breadth of each pair. All computations were
performed using STATISTICA version 7.0 for Windows
(StatSoft
2004). Statistical significance was set at P<0.05.
Results
Population size of peregrines almost doubled during the
study period, starting with five pairs until a maximum of
nine pairs in 2002. In relation to dietary analysis, 42% of
data came from pellet collection, 22% from direct observa-
tions, and 36% from prey remains collected in nests and
roosting places (N=820; Table 1). Overall the diet was
Table 1 Descriptive parameters recorded for the nine pairs of
peregrine falcon in the study area
Pair
no.
Prey
items
Monitored
years
Average
productivity
(chicks/year)
Distance to
nearest
neighbor (m)
Distance
to village
(m)
1 132 21 2.29 5,800 3,800
2 93 20 2.35 6,160 3,600
3 91 19 2.63 8,450 7,300
4 136 16 2.17 8,450 3,500
5 112 21 2.55 3,650 3,000
6 68 6 2.40 6,160 2,000
7 84 6 2.00 3,650 2,000
8 54 5 2.60 1,300 1,500
9 50 5 2.60 9,150 3,000
Eur J Wildl Res (2009) 55:125132 127
essentially composed by birds, accounting for 99.15% of
the prey items fro m at le ast 35 differe nt species (Tab le 2).
Six mammals were detected as a prey, including four
rabbits, Oryctolagus cuniculus, and two undetermined
bats (probably Myotis or Rinholo phus spp.). We also
could observe the contribution to the nest of one ladder
snake (Rinechis scalaris)50cminlengthapproximately.
Average prey mass weighted according to its frequency
in the diet was 204.79 g (range=91,200, N=820). The
Gini index of diversi ty range d from 0.73 to 0.88 ( mean=
0.83, SD=0 .05). Niche breadth ranged from 2.32 to 5.00
(mean=3.81, S D=0.95). Average dietary ove rlap was
0.93 (range=0.840.97), higher than that expected by
chance (expected die tary overlap=0.17, P<0.000 1).
Among bird preys, the family Columbidae accounts for
43.78% of the diet by number of individuals and 68.69% by
mass. Within Columbidae, 69.70% of the bioma ss corre-
sponds to rock pigeon, Columba livia (N=268 items), with
the rest corresponding to common wood pigeon, Columba
palumbus (19.90%) and stock dove, Columba oenas
(10.40%). There were no differences in the proportion of
pigeon consumption among pairs (χ
2
=0.089, df=8,
P>0.05), showing that all peregr ine pairs prey mainly on
this family. More interestingly, the proportion of pigeons in
the diet was positively associated with peregrine numbers
(Spearman r=0.79, P<0.001, N=21; Fig. 2) and average
productivity (Spearman r=0.66, P=0.052, N=9), this in the
threshold of significance. Conversely, average productivity
Table 2 Summary of the diet
of peregrine falcons in eastern
Spain (19822002), as esti-
mated by direct observations,
pellets, and prey remains
Rows are organized in
descending percentage of prey
by mass
a
An average of 30 g/item was
used to obtain the % of prey
mass (Cramp et al. 19771985)
b
Mammals
c
Reptile
Prey type Number of items % number of preys % prey mass
Rock pigeon, Columba livia 268 32.68 47.88
Common wood pigeon, Columba palumbus 51 6.22 13.67
Magpie, Pica pica 64 7.80 8.19
Stock dove, Columba oenas 40 4.88 7.15
Partridge, Alectoris rufa 19 2.32 5.43
Spotless starling, Sturnus unicolor 47 5.73 2.38
Unidentified passerines
a
125 15.24 2.23
Rabbit, Oryctolagus cuniculus
b
4 0.49 2.14
Eurasian turtle dove, Streptopelia turtur 24 2.93 2.00
Hoopoe, Upupa epops 44 5.37 1.76
Blackbird, Turdus merula 22 2.68 1.05
Eurasian jackdaw, Corvus monedula 7 0.85 1.00
Collared dove, Streptopelia decaocto 6 0.73 0.71
Common pheasant, Phasianus colchicus 1 0.12 0.71
Little owl, Athene noctua 6 0.73 0.63
Green woodpecker, Picus viridis 5 0.61 0.54
Common krestel, Falco tinnunculus 3 0.37 0.37
Sky lark, Alauda arvensis 12 1.46 0.29
Common swift, Apus apus 12 1.46 0.29
Rock sparrow, Petronia petronia 14 1.71 0.25
Song thrush, Turdus philomelos 5 0.61 0.21
Moorhen, Gallinula chloropus 1 0.12 0.19
Great spotted cuckoo, Clamator glandarius 2 0.24 0.18
Crested lark, Galerida cristata 6 0.73 0.16
Common quail, Coturnix coturnix 2 0.24 0.12
Greenfinch, Carduelis chloris 5 0.61 0.08
Blue rock thrush, Monticola solitarius 2 0.24 0.07
Mistle thrush, Turdus viscivorus 1 0.12 0.07
House sparrow, Passer domesticus 4 0.49 0.07
Goldfinch, Carduelis carduelis 6 0.73 0.05
Black redstart, Phoenicurus ochruros 5 0.61 0.05
Eurasian crag martin, Ptyonoprogne rupestris 3 0.37 0.04
Black wheatear, Oenanthe leucura 1 0.12 0.02
Ladder snake, Rinechis scalaris
c
1 0.12 0.01
Bat spp.
b
2 0.24 0.01
Total 820 100 100
128 Eur J Wildl Res (2009) 55:125132
was lower when dietary breadth was higher (Spearman
r=0.90, P=0.002, N=9).
Discussion
Direct observation of prey hunting and observation of prey
contribution to the nest has been suggested as the best
method to determine the diet of peregrine falcons (Dekker
1980; Bird and Aubry 1982; Thiollay 1982). However,
these methods require a great deal of time, and studies
based only on them are scarce (Marti 1987). Usually, diet
studies on peregrine falcon have been based on the
collection of prey remains and pellets, but they are blamed
for bias in the analysis of diet (Mearns 1983). Whereas
pellet analysis tend to overestimate consumption of small to
medium-sized preys, studies based on prey remains tend to
overestimate the consum ption of large-size preys (Mearns
1983; Oro and Tella 1995; Zuberogoitia et al. 2002). In this
study, we have combined the use of all methods aforemen-
tioned in order to minimize the possible bias, as demon-
strated by several authors (Collopy 1983; Simmons et al.
1991; Mersmann et al. 1992; Mañosa 1994; Oro and Tella
1995; Zuberogoitia et al. 2002). However, other methods
like video recording directly at nest sites could also be used
(Margalida et al. 2006; review in Reif and Tornberg 2006;
López-López and Urios, submitted).
Peregrines can prey on preys lower than 10 g up to preys
larger than them and over 1,2001,500 g (Ratcliffe 1993).
This author estimated the optimal prey mass around
100150 g depending on factors like sex, temperature,
health status, experience, etc. (Ratcliffe 1993; Jenkins and
Avery 1999). Other authors estimate 188 g of prey mass per
day necessary for an adult and calculated a prey delivery
rate of 222 g per nestling (and dependent fledgling) per day
(Redpath and Thirgood 1997). In any case, pigeons with an
average mass of 300450 g are above the optimal prey
mass. Our results show that peregrines prey mainly on
pigeons without differences among pairs in the proportion
of this type of prey in the diet. Similar results have been
found in other studies of this species, showing the key role
of pigeons in the peregrinesdiet(reviewinValkamaetal.
2005). For example, pigeons represent nearly 50% in the diet
by number in UK (Ratcliffe 1993) and Scotland (Mearns
1983; Redpath and Thirgood 1997) and even 57.8% in
France (Bayle 1981). It has been suggested that peregrines
would tend to a generalization in prey consumption as the
climate become s more extreme (e. g., tundra, deserts),
whereas they would tend to specialization in regions with a
temperate climate (Jenckins and Avery 1999). Our results
might support this prediction, taking into account the high
proportion of pigeon in the diet (in some cases representing
more than 50% of prey items detected). However, another
explanation is that peregrine falcons prey according to prey
availability (Ratcliffe 1993;Zuberogoitiaetal.2002), or
even that some pairs could have a preference for a certain
class of prey (Thiollay 1988; Rosenfield et al. 1995).
In our study area, pigeon availability has notably
increased from the eighties. This increase is related with
the increase in pigeon fancying licenses and the creation of
new pigeon fanciers clubs (Mínguez et al. 2005). Unfor-
tunately, even though we could not tag racing pigeons to
conduct a specific study on the impact of peregrines on this
type of prey, the general increase of the number of pigeon
fancying licenses and pigeon fanciers clubs can be taken as a
Table 3 Summary of the pigeon fancying activity in six municipalities of the study area
Municipality Population
a
Pigeon
societies
Year of
creation
Initial
licenses
Licenses in
2005
Pigeon
barriers
Flying days/
week
Pigeons/
day
Pigeons/
competition
Segorbe 8,023 1 1965 3 47 1 7 150 200
Jérica 1,561 1 1990 4 11 3 3 60/80 90
Altura 3,140 1 1975 5 40 2 4 100 100
Soneja 1,383 1 1980 1 5 2 4 60 90
Castellnovo 1,026 1 1980 2 23 2 4 90 90
Sot de Ferrer 407 1 1980 No data No data No data 3 70 90
Data were obtained by interviewing pigeon fanciers directly and kindly provided by Mínguez et al. (2005)
a
Data taken from the Spanish National Institute of Statistics (www.ine.es)
Fig. 2 Relationship between pigeon consumption and the observed
duplication of population size between 1982 and 2002
Eur J Wildl Res (2009) 55:125132 129
proper surrogate on the increase of pigeon availability in our
study area (Table 3). Currently, there are 953 pigeon fancying
licenses and 40 clubs in the whole Castellón province. More
specifically, for example, in the municipalities included in
the study area, there are flying nearly 100150 pigeons per
training day, and nearly 2% of these pigeons are lost every
day, becoming available for falcons (data provided directly
by the pigeon fanciers; Table 3).
Our results suggest that an increase in pigeon availability
has been associated with both an increase in population size
and an increase in breeding performance of a peregrine
falcon population in eastern Spain. From our point of view,
this could be explained as the synergistic effect of a decline
in direct persecution, consequence of the publication of the
Spanish Law of protection of wild Flora and Fauna in 1989
(Law 4/89) and the Valencian Law of Protection of Natural
Areas in 1994 (Law 11/94), and a slight but continuous
increase of pigeon availability in the study area. As pigeon
availability increased, its proportion in the diet also did the
same, decreasing the dietary breadth. According to Watson
(1997), analyzing golden eagles(Aquila chrysaetos) diet,
raptors should be more successful when they can concen-
trate on hunting few prey species which lie in the birds
optimal size range. This could also explain the higher
breeding per formance observed in the study area, in
contrast to that reported in other parts of the world
(J. Verdejo and P. López-López 2008).
Conservation implications
In some European r egions, p igeon f ancie rs perceiv e
raptors as the main cause of losses, demanding political
measures to control peregrine numbers actively or even
persecuting peregrines to a significant degree. In these
areas, estimating the predation on racing pigeons (as
opposed to birds which have strayed, birds which have
gone feral, or wild pigeons) becomes an important issue.
Racing birds, strays, and feral s are usually ringed.
However, it is difficult to distinguish among these
different types of pigeons in the diet without conducting
a specific sampling design, as in our case. Thus,
although we collected a high number of rings, we were
unfortunately unable to calculate the proportion of the
different pigeon types exactly (feral, racing, strays, or
wild). Anyway, recent studies have demonstrated the
strong limitations of using ring recoveries to evaluate the
impact of peregrine kills on racing pigeons (Parrott et al.
2008).
The increase in pigeon fanciers has been focused in large
villages within the study area. This phenomenon brings
peregrine falcons closer to populated places in their hunting
search. This situation becomes worse provided that the
majority of competitions take place from Dece mber to May,
overlapping with the period when peregrines start to breed
in the region and have a corresponding higher need of prey
intake. This result corresponds with that reported in UK
where the increase and decrease in the pigeon component
of the diet coincides with the start and end of the racing
pigeon season respectively, indicating the importance of
racing pigeon s (or strays or ferals) as a food supply (Dixon
et al. 2003). Taking into account the fact that racing pigeons
could reach a value up to 10.000 , this could cause a
conflict of interests between peregr ines and pigeon fanciers.
As a consequence, this could result to an increased risk of
mortality by direct persecution. Furthermore, another threat
to falcon s (an d other raptors suc h as the endangered
Bonellis eagle Aquila fasci ata) is the transmission of
diseases from pigeons to raptors, such as trichominiasis,
caused by the flagellated protozoon Trichomonas gallinae
(Höfle et al. 2004; Villanúa et al. 2006; Hegemann et al.
2007). In accordance to these, conservation measures aimed
at preventing direct persecution and disease transmission
are encouraged.
Finally, there are few reported studies aimed at quanti-
fying the effect of raptor predation in racing pigeons (but
see Henderson et al. 2004 and Parrot et al. 2008). Although
not conclusive, there is no evidence that birds of prey cause
large-sc ale los ses of racing pigeons (Henderson et al.
2004). For example, Parrot et al. (2008) estimated that
peregrine kills based on daily food intake
represented 13
40% of total losses of Scottish racing pigeons to all causes.
On this subject, it would be interesting to perform a long-
term study of the likely impact of peregrines and other
raptors on racing pigeons in the Mediterranean region.
Here, the unique study made shows that the perception of
local pigeon fanciers of raptors as a risk for pigeon losses
figures as the fourth of five causes of concern, after
collisions with power lines and cables, losses caused by
wild pigeons, terrestrial predators, and only before
natural diseases (Mínguez et al. 2005). An additional study
specifically aimed at d eterm in ing the effectiveness of
pigeon barriers would also be necessary. To date, this
has been the only measure implemented by the local
administration, even though the likely counterproductive
effects like raptor habituation to have pigeons as an easy-to-
capture prey have not been determined. Future research
ought to include such long- term specific analysis.
Acknowledgments We would like to thank everybody who helped
in the field work. Juan Manuel Pérez of the University of Elche kindly
provided unpublished data about their study of pigeon fancying in the
Valencian Community. Gary Entsminger kindly helped with niche
overlap calculations. Clara García, Álvaro Soutullo, Miguel Ángel
Gómez and Phillip Whitfield improved the English and made valuable
comments on an early draft of the manuscript. P. López-López is
supported by FPU grant of the Spanish Ministerio de Ciencia e
Innovación (reference AEP2005-0874).
130 Eur J Wildl Res (2009) 55:125132
References
Bayle P (1981) Quelques données sur le régime alimentaire du faucon
pèlerin (Falco peregrinus) dans le massif vosgien. Ciconia 5:5156
Bird DM, Aubry Y (1982) Reproductive and hunting behaviour in
peregrine falcons, Falco peregrinus, in southern Quebec. Can
Field Nat 96:167171
Collopy MW (1983) A comparison of direct observations and
collections of prey remains in determining the diet of golden
eagles. J Wildl Manage 47:360368 doi:10.2307/3808508
Cramp S, Simmons KEL (1980) The birds of Western Paleartic, vol.
II. Oxford University Press, UK
Cramp S et al (19771985) Handbook of the birds of Europe, the Middle
East and North Africa, vols IIV. Oxford University Press, UK
Del Hoyo J, Elliot A, Sargatal J (1994) Handbook of the birds of the
world, vol. 2. New world vultures to guineafowl. Lynx Edicions,
Barcelona, Spain
Dekker D (1980) Hunting success rates, foraging habits, and prey
selection of peregrine falcons migrating through central Alberta.
Can Field Nat 94:371382
Dixon A, Richards C, Lawrence A, Thomas M (2003) Peregrine
(Falco peregrinus) predation on racing pigeons (Columbia livia)
in Wales. In: Thompson DBA, Redpath SM, Fielding AH,
Marquiss M, Galbraith CA (eds) Birds of prey in a changing
environment. The Stationer Office, Edinburgh, pp 255261
Gotelli NJ, Ellison AM (2004) A primer of ecological statistics.
Sinauer, Sunderland, Massachusetts, USA
Gotelli NJ, Entsminger GL (2001) EcoSim: null models software for
ecology. Version 7.0. Acquired Intelligence Inc. & Kesey-Bear.
http://homepages.together.net/gentsmin/ecosim.htm
Gotelli NJ, Graves GR (1996) Null models in ecology. Smithsonian
Institution Press, Washington DC, U.S.A
Haefner JW (1988) Niche shifts in greater Antillean Anolis commu-
nities: effects of niche metric and biological resolution on null
model tests. Oecologia 77:107117 doi:10.1007/BF00380933
Hegemann A, Hegemann ED, Krone O (2007) Trichomonosis in a
free-living stock dove (Columba oenas). Eur J Wildl Res 53:235
237 doi:10.1007/s10344-007-0090-6
Henderson I, Parrott D, Moore N (2004) Racing pigeonsimpact of
raptor predation. Report to Scottish Natural Heritage & Scottish
Homing Union. Central Science Laboratory. March 2004. http://
www.snh.org.uk/pdfs/pigeons_raptors_report.pdf
Höfle U, Gortázar C, Ortíz JA, Knispel B (2004) Outbreak of
trichomoniasis in a woodpigeon wintering roost. Eur J Wildl Res
50:7377 doi:10.1007/s10344-004-0043-2
Inger RF, Colwell RK (1977) Organization of contiguous communities
of amphibians and reptiles in Thailand. Ecol Monogr 47:229253
doi:10.2307/1942516
Jenkins A, Avery G (1999) Diets of breeding peregrine and lanner
falcons in South Africa. J Raptor Res 33:190206
Jutglar F, Masó A (1999) Aves de la Península Ibérica. Editorial
Planeta, S.A. Barcelona, Spain
Lawlor LR (1980) Structure and stability in natural and randomly
constructed competitive communities. Am Nat 116:394408
doi:10.1086/283634
Levins R (1968) Evolution in changing environments. Princeton
University Press, Princeton, USA
Magurran AE (2003) Ecological diversity and its measurements.
Princeton University Press, Princeton, NJ, USA
Mañosa S ( 1994) Goshawk diet in a Mediterranean area of
northeastern Spain. J Raptor Res 28:8492
Margalida A, Ecolan S, Boudet J, Bertrán J, Martínez JM, Heredia R
(2006) A solar-powered transmitting video camera for monitoring
cliff-nesting raptors. J Field Ornithol 77:712 doi:10.1111/j.1557-
9263.2006.00007.x
Martí CD (1987) Raptor food habit studies. In: Giron Pendleton BA,
Millsap BA, Cline K, Bird DM (eds) Raptor management
techniques manual. National Wildlife Federation, Washington,
DC, USA, pp 6780
Mearns R (1983) The diet of the peregrine Falco peregrinus in south
Scotland during the breeding season. Bird Study 30:8190
Mersmann TJ, Buehler DA, Fraser JD, Seegar JKD (1992) Assessing
bias in studies of bald eagle food habits. J Wildl Manage 56:73
78 doi:10.2307/3808792
Mínguez E, Pérez JM, Sanz A, Sales A, Sánchez-Zapata JA, Giménez A,
Botella F (2005) Pigeon-fancying and raptor conservation in the
Valencian community. Report to Conselleria Territori i Habitatge.
Generalitat Valenciana, November 2005
Monneret RJ (2000) Le faucon pèlerin. Delechauux et niestle, Suisse
Newton I (1979) Population ecology of raptors. T & AD Poyser,
Berkhamstead, UK
Oro D, Tella JL (1995) A comparison of two methods for studying the
diet of the peregrine falcon. J Raptor Res 29:207210
Parrott D, Henderson I, Deppe C, Whitfield P (2008) Scottish racing
pigeons killed by peregrine falcons Falco peregrinus: estimation
of numbers from ring recoveries and peregrine daily food intake.
Bird Study 55:3242
Pianka ER (1973) The structure of lizard communities. Annu Rev
Ecol Syst 4:5374 doi:10.1146/annurev.es.04.110173.000413
Ratcliffe DA (1993) The peregrine falcon. T & AD Poyser, London,
UK
Redpath SM, Thirgood SJ (1997) Birds of prey and red grouse. H.M.
Stationery Office, London
Reif V, Tornberg R (2006) Using time-lapse digital video recording
for a nesting study of birds of prey. Eur J Wildl Res 52:251258
doi:10.1007/s10344-006-0039-1
Rosenfield R, Schneider J, Papp JM, Seegar WS (1995) Prey of
peregrine falcons breeding in West Grenland. Condor 97:763
770 doi:10.2307/1369184
Sale PF (1974) Overlap in resource use, and interspecific competition.
Oecologia 17:245256 doi:10.1007/BF00344924
Schoener TW (1974) Resource partitioning in ecological communities.
Science 185:2739 doi:10.1126/science.185.4145.27
Simmons RE, Avery DM, Avery G (1991) Biases in diets determined
from pellets and remains: correction factors for a mammal and
bird-eating raptor. J Raptor Res 25:6367
StatSoft (2004) STATISTICA (data analysis software system), version
7. StatSoft Incorporated, Tulsa, OK, USA
Steenhof K, Kochert MN (1982) An evaluation of methods used to
estimate raptor nesting success. J Wildl Manage 46:885893
doi:10.2307/3808221
Steenhof K, Kochert MN (1985) Dietary shifts of sympatric buteos
during a prey decline. Oecologia 66:616 doi:10.1007/
BF00378546
Thiollay JM (1982) Les ressources alimentaires, facteur limitant le
reproduction dune population insulaire de faucons pèlerins,
Falco peregrinus brookei. Alauda 50:1644
Thiollay JM (1988) Prey availability limiting an island population of
peregrine falcon in Tunisia. In: Cade TJ, Enderson JH, Thelander
CG, White CM (eds) Peregrine falcon populations. Their
management and recovery. The Peregrine Fund Inc. Boise,
Idaho, USA, pp 701710
Valkama J, Korpimäki E, Arroyo B, Beja P, Bretagnolle V, Bro E et al
(2005) Birds of prey as limiting factors of gamebird populations
in Europe: a review. Biol Rev Camb Philos Soc 80:171203
doi:10.1017/S146479310400658X
Verdejo J (1991) Las aves de presa diurnas y nidificantes en el Alto
Palancia (S.O Castellón). Ph.D. Thesis. Universidad de Valencia.
Valencia, Spain.
Verdejo J (1994) Breeding biology and food of the goshawk (Accipiter
gentilis) in a Mediterranean area. Ardeola 41:3743
Eur J Wildl Res (2009) 55:125132 131
Verdejo J, López-López P (2008) Long-term monitoring of a peregrine
falcon population: size , breeding performance and nest-s ite
characteristics Ardeola 55(1):8796
Villanúa D, Höfle U, Pérez-Rodríguez L, Gortázar C (2006)
Trichomonas gallinae in wintering Common Wood Pigeons
Columba palumbus in Spain. Ibis 148:641648 doi:10.1111/
j.1474-919X.2006.00561.x
Watson J (1997) The golden eagle. T. & A.D. Poyser Ltd., London, UK
Winemiller KO, Pianka ER (1990) Organization in natural assemb-
lages of desert lizards and tropical fishes. Ecol Monogr 60:2755
doi:10.2307/1943025
Zuberogoitia I, Fernando J, Moneo R, Torres JJ (2002) El Halcón
Peregrino. Diputación Foral de Bizkaia Departamento de Agri-
cultura, Bilbao, Spain
132 Eur J Wildl Res (2009) 55:125132
... In fact, true specialized falcons show a clear preference towards a few species of similar size (Fig. 4.8;Rudebeck 1951;Norrdahl and Korpimäki 2000). Pigeons are the most important prey for peregrine falcons, and an increase in their availability positively influences the population size and breeding performance of this predator (Mearns 1983;López-López et al. 2009). Accordingly, peregrine falcons' average productivity is lower when dietary breadth is higher (López-López et al. 2009). ...
... Pigeons are the most important prey for peregrine falcons, and an increase in their availability positively influences the population size and breeding performance of this predator (Mearns 1983;López-López et al. 2009). Accordingly, peregrine falcons' average productivity is lower when dietary breadth is higher (López-López et al. 2009). In fact, specialized bird-eater falcons such as peregrine falcons and merlins tend not to switch to other prey than preferred prey (Fig. 4.4;Petty et al. 1995). ...
... ;Aghababyan 2006;Leonardi and Mannino 2007;Probst et al. 2007;López-López et al. 2009;Chavko and Deutschová 2012;Bijlsma 2013;Keyl 2013;Bondì et al. 2014Bondì et al. , 2016Chavko et al. 2014; van't Hof 2014; Sutton 2015; Bakour and MoulaÏ 2019; Xirouchakis et al. 2019) Fig. 4.4 Overall diet composition of Western Palearctic falcons ordered by decreasing proportions 4.3 Diet their diet choice than are bird-eaters and generalists (Fig. 4.5;Korpimäki and Marti 1995). ...
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Falcons show fine anatomical and physiological adaptations to capture different kinds of prey, but the mean prey mass correlated positively with mean mass of the falcon. The proportion of birds affect the diet breadth at species level, and the proportion of invertebrates negatively correlate with the rate of mammals. Thus, mammalian-eating falcons able to switch to alternative prey, and bird-eating falcons are forced to enlarge their foraging area to find enough avian prey. Ultimately, prey size and the type of prey increase the reversed size dimorphism (RSD) of falcons from insects to mammals to birds as prey. Falcons show a certain dietary plasticity due to environmental conditions that limit the distribution of prey and their abundances. The food composition can differ significantly depending on the season and falcons adjusted hunting efforts and techniques accordingly. In addition, the breadth of the food niche was positively correlated with habitat heterogeneity that ultimately increases the number of prey species, especially birds. Hunting techniques adopted by falcons depend on prey size and prey type, and their availability is mainly related to variable environmental factors. Anyway, they prioritize saving energy when foraging than time spent during foraging bouts. Avian predators are one of the major factors modifying avian and mammalian prey assemblages of a territory. Spatial synchrony in rodent population fluctuation is well described at boreal ecosystem and also in Central Europe but at a large spatial scale. Falcons that exclusively exploit migrating small birds for rearing young need to move to their breeding areas every year and then leave these areas outside the breeding season due to the absence of alternative prey out the seasonal migration periods. Flocking, vigilance, and mobbing are adopted by prey against falcons’ attacks, but hunting success of falcons is highest in attacks on small flocks. Populations of specialist predators often fluctuate with populations of preferred prey species. For example, stable, regular, synchronous, 10–12-year quasi-cycles have been demonstrated in grouses and gyrfalcons.
... This also gave us a better understanding of where the three predators were most abundant. We chose to examine these three predators because they are the only three diurnal avian predators known to nest in New York City (Fowle & Kerlinger, 2001) and eat pigeons (Dunn & Tessaglia, 1994;L opez-L opez, Verdejo, & Barba, 2009;Roth & Lima, 2003). ...
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... Raptors hunt for their prey either opportunistically, that is, in proportion to their relative abundances, or because of their relative profitability (Tores et al., 2005;Seaton et al., 2008;McKinnon et al., 2013;Rodriguez et al., 2020). Studies on temporal and spatial variation in the diet composition of raptors are important to understand their foraging ecology, breeding performance, population density, or habitat selection (Litvaitis, 2000;Lopez-Lopez et al., 2009;Di Vittorio et al., 2017). ...
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We investigated temporal changes in diet composition of the Montagu's Harrier Circus pygargus breeding in natural habitat (calcareous peat bog) in SE Poland. We characterized diet composition in a three-year period (2007–2009), based on pellet analyses. We investigated whether diet composition was affected by years or stage of breeding. We compared diet of the studied population between 2000s and 1990s and with other populations. We found that the food of the studied population was dominated by insects and mammals (by number) and mammals and birds (by biomass). Biomass and abundance of main prey items differed between studied years because of different air temperatures. We found some interannual differences in contribution of some prey items including higher number of thermophilic prey (insects and am-phibians) in warmer years. Comparison of pellet composition in the 1990s and 2000s revealed significant increase in the abundance of thermophilic prey (insects and rep-tiles) and decrease of mammals including Microtus voles and birds. Those changes may be linked to habitat changes in areas neighboring peat bogs and climate change- induced changes in prey communities. The studied population was able to respond to changes in foraging habitats and prey composition by opportunistic foraging on easily available prey. The diet of the studied population is the most similar to the geographically closest populations foraging in similar habitats and characterized by high contribution of insects.
... Rock Doves and their eggs are preyed on by many other species. They form a particularly important prey base for urban birds of prey such as Peregrine Falcons (Falco peregrinus; López-López et al., 2009). In south-west England, 47% of the diet of Peregrine Falcons was composed of pigeons and doves, while in Porto Alegre, Brazil, it was 68.5% and in Santos it was 80.9% (Silva 1997;Drewitt and Dixon, 2008). ...
Chapter
This 381-paged book covers the biology, ecology, impact and management of 34 common alien invasive species, with reviews on the history and context of avian introductions and invasions in five major regions (Oceania, Africa, Europe (including the Middle East, Asia and South America)), as well as management challenges and the potential of citizen science for monitoring alien birds. The book pitches at the introductory level and is ideal for readers to gain a quick and comprehensive view of the current status of global avian invasions. It has brought the records and research of avian invasion one step ahead of other alien invasive animal taxa. Many chapters contain distribution maps and data tables on the diet and morphology of the species, providing a good reference for the species and its management issues. Each chapter also contains a rich list of references that could help readers dive further into the topic.
... data), the main prey of the Barbary Falcon on La Palma was the rock pigeon, which includes wild, feral and domestic individuals. This taxon also forms the bulk of the diet of many other European populations of Peregrine Falcon (Ratcliffe 1993, Zuberogoitia et al. 2002, Shawyer et al. 2003, Parrott et al. 2008, López-López et al. 2009), as it does in the rest of the Canary Islands authors' unpubl. data). ...
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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.
... Direct observations of hunting behaviour, analysis of pellets, and collection of prey remains are methods usually employed to study avian diet (e.g. Mersmann et al. 1992;Lewis et al. 2004;López-López et al. 2009). However, these methods may give conflicting results. ...
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Context Dietary analyses are essential to achieve a better understanding of animal ecology. In the case of endangered species, assessing dietary requirements is crucial to improve their management and conservation. The Bonelli’s eagle (Aquila fasciata) has experienced a severe decline throughout its breeding range in Europe and, in Italy, fewer than 50 pairs remain, and only in Sicily. This species is subject to major threats, including changes in landscape composition and, consequently, prey availability, which is further aggravated by the occurrence of viral diseases in the case of rabbits. Aims To provide current data on the diet of the Bonelli’s eagle in Sicily during the breeding period and to examine dietary shifts with regard to previous studies conducted in the same study area. To discuss possible implications for conservation of the Italian population of this endangered species. Methods We used a combination of three methods, including pellet analysis, collection of prey remains, and imagery from camera-traps installed at nests, to examine the diet of 12 breeding pairs of Bonelli’s eagle from 2011 to 2017. We compared this information with data collected between 1993 and 1998 in the same study area. Key results In number, birds were the most frequently predated items (61.6%), followed by mammals (36.88%) and reptiles (1.52%). However, in terms of biomass, mammals were the main prey (65.71%), followed by birds (34.12%) and reptiles (0.17%). There was a decrease over the course of the current decade in the consumption of European wild rabbit (Oryctolagus cuniculus), which was compensated for with an increase in both dietary diversity and breadth in bird consumption, a trend not observed in the earlier study in the same region. Conclusions Here, we provide an updated assessment of diet composition of Bonelli’s eagle during the breeding period. Interestingly, we found significant differences within the study period (2011–2017) in terms of frequency of occurrence, percentage of biomass, dietary diversity and dietary breadth in a species at risk. Furthermore, we found significant differences between the two study periods in both frequency and percentage of biomass, with significant changes in the consumption of lagomorphs and birds. Implications Our results indicated that shifts in the diet are linked to changes in prey abundance, which may be contributing to population declines in the Bonelli’s eagle population in Sicily. Overall, measures aimed at increasing main dietary prey should be promoted to favour occupation of new territories and enhance vital demographic parameters (i.e. breeding success and survival rate) of Bonelli’s eagle across the species range. This would be particularly important for small isolated populations such as the Sicilian one.
... Direct observations of hunting behaviour, analysis of pellets, and collection of prey remains are methods usually employed to study avian diet (e.g. Mersmann et al. 1992;Lewis et al. 2004;López-López et al. 2009). However, these methods may give conflicting results. ...
Article
Full-text available
Context: Dietary analyses are essential to achieve a better understanding of animals’ ecology. In the case of endangered species, assessing dietary requirements is crucial to improving their management and conservation. The Bonelli’s eagle (Aquila fasciata) has experienced a severe decline throughout its breeding range in Europe and, in Italy, fewer than 50 pairs remain, and only in Sicily. This species is subject to major threats including changes in landscape composition and consequently, prey availability, which is further aggravated by the occurrence of viral diseases in the case of rabbits. Aims: To provide current data on the diet of the Bonelli’s eagle in Sicily during the breeding period and to examine dietary shifts with regard to previous studies conducted in the same study area. To discuss possible implications for conservation of the Italian population of this endangered species. Methods: We used a combination of three methods, including pellet analysis, collection of prey remains, and imagery from camera-traps installed at nests, to examine the diet of 12 breeding pairs of Bonelli’s eagle from 2011 – 2017. We compared this information with data collected between 1993 and 1998 in the same study area. Key results: In number, birds were the most frequently predated items (61.6%), followed by mammals (36.88%) and reptiles (1.52%). However, in terms of biomass, mammals were the main prey (65.71%), followed by birds (34.12%) and reptiles (0.17%). There was a decrease over the course of the current decade in the consumption of European wild rabbit (Oryctolagus cuniculus) which was compensated for with an increase in both dietary diversity and breadth in bird consumption; a trend not observed in the earlier study in the same region. Conclusions: Here we provide an updated assessment of diet composition of Bonelli’s eagle during the breeding period. Interestingly, we found significant differences within the study period (2011 – 2017) in terms of frequency of occurrence, percentage of biomass, dietary diversity and dietary breadth in a species at risk. Furthermore, we found significant differences between the two study periods in both frequency and percentage of biomass, with significant changes in the consumption of lagomorphs and birds. Implications: Our results indicate that shifts in diet are linked to changes in prey abundance, which may be contributing to population declines in the Bonelli’s eagle population in Sicily. Overall, measures aimed at increasing main dietary prey should be promoted to favour occupation of new territories and enhance vital demographic parameters (i.e., breeding success and survival rate) of Bonelli’s eagle across the species range. This would be particularly important for small isolated populations like the Sicilian one.
... Since 2009, local residents have been helping to collect feathers and, also in 2009, an MSc student from the University of Exeter, Lin Chen Yu, undertook daily collections for three months as part of a more detailed study (Chen Yu 2009). This close scrutiny retrieved dropped or discarded material, including whole or part carcasses, feathers, heads/skulls, wings, legs, rings and pellets (Oro & Tella 1995, López-López et al. 2009). While pellets have been collected, they usually reveal just powdery pigeon feathers and little else; sometimes a bird ring. ...
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Until relatively recently Peregrines have been regarded as a rural bird. As their populations have increased over the past 20 years, Peregrines have increasingly become urban birds. One of the earliest locations to be occupied by Peregrines in the UK was on a church in Exeter, in the county of Devon. Over the past 20 years we have studied their diet, collecting prey remains on a regular basis. The results reveal that Feral Pigeons Columba livia comprise one third of the diet by frequency and just over half of the diet when measured by mass. The remainder of the diet comprises a wealth of other species including wading birds, other doves and pigeons, ducks, gulls and terns, and rails. A selection of species eaten by the Peregrines reveal that they are hunting at night, taking certain wading birds, rails and grebes, that would be difficult to catch by day and are known to migrate at night. This study is the most comprehensive to date and reveals that while the Feral Pigeon is an important part of the diet, contrary to public opinion, it is by no means the only species that Peregrines eat. In fact, the remaining half of the diet, by mass, comprised 101 other species of bird and three species of mammal. Such dietary studies help dispel myths about peregrines feeding habits and ensure that their conservation and protection is based on evidence.
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Les populations d’oiseaux de proie sont essentielles à l’équilibre des écosystèmes. Au Québec, la gestion et la conservation de ces oiseaux relèvent du ministère des Forêts, de la Faune et des Parcs (MFFP). Or, leurs populations sont méconnues, ce qui limite les capacités du MFFP à assurer sa mission. La présente étude vise à combler ce manque pour les 16 rapaces diurnes à l’aide de trois objectifs : (1) clarifier le rôle de ces espèces dans les écosystèmes et les menaces qui pèsent sur elles; (2) analyser les tendances des populations et (3) dresser un constat quant à l’état des populations et proposer, lorsque cela est requis, des améliorations à apporter aux suivis des populations. Nous avons modélisé les tendances des populations sur trois décennies à partir des données des quatre observatoires d’oiseaux en migration et des données de science citoyenne (Recensement des oiseaux de Noël; eBird et Étude des populations d’oiseaux du Québec [EPOQ]). Les résultats indiquent que deux espèces désignées vulnérables, le pygargue à tête blanche et le faucon pèlerin, se sont rétablies. En revanche, d’autres espèces montrent des tendances au déclin ou contradictoires, comme l’aigle royal (désigné vulnérable) ou le busard des marais, et il serait souhaitable de les surveiller davantage. Enfin, la situation est inquiétante pour la crécerelle d’Amérique et la buse pattue. Cette étude démontre l’importance de connaître les tendances des populations de ces espèces afin de mieux les protéger. Nous suggérons de procéder à une analyse identique pour les rapaces nocturnes afin d’obtenir un portrait complet pour les oiseaux de proie du Québec. Dans la mesure où les données le permettent, d’autres espèces en situation précaire pourraient également bénéficier d’une telle analyse.
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Asistencia técnica financiada por el Cabildo Insular de La Palma.
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Surveys of raptor nesting populations can yield markedly different results depending on sampling and analytical procedures. Analysis of reproductive data for 3 raptor species in southwestern Idaho showed that productivity estimates based on pairs found early in the nesting season tend to be lower than those for pairs found late. Two factors seem to be responsible. First, researcher visits to nests early in the nesting season may cause nest failure, especially for eagles and red-tailed hawks (Buteo jamaicensis). Second, successful pairs are more conspicuous and are more easily located than unsuccessful pairs later in the season. To obtain an unbiased estimate of reproduction per pair by large raptors, researchers may use a sample of known traditional pairs to assess percent of pairs breeding, begin surveys during incubation to identify breeding pairs, and avoid disturbing nesting pairs until just before young fledge to determine nest success. Nest success per pair can be calculated in 1 of 3 ways. A method that incorporates the Mayfield technique may be most appropriate.
Article
After an unsuccessful attempt in 1979, peregrine falcons nested at a site in southern Quebec in 1980. The pair, made up of an apparent wild anatum male and captive-bred-and-released female, produced 2 young, the first known to fledge from a cliff site in eastern Canada south of the tree line, excluding Labrador, since 1961. Over both years, 69 of 197 hunting attempts by the male were successful for a success rate of 35%. Of 218 hunting attempts by both sexes, 78% took place between 0500 and 1000 h. An attack with more dives at the prey was more likely to be successful. The principal prey species were blue jays Cyanocitta cristata up to 7 June, replaced by blackbirds and swallows after that date. -from Authors
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The diet of Accipiter gentilis is described throughout the year in La Segarra, Catalonia where one of the densest goshawk populations recorded in Europe was found. Red-legged partridge Alectoris rufa, rabbit Oryctolagus cuniculus, wood-pigeon Columba palumbus, jay Garrulus glandarius, magpie Pica pica, thrushes Turdus spp. and red squirrel Sciurus vulgaris formed the bulk of the goshawk diet. Nestling and fledgling birds were very important during the breeding period, but the rabbit was the main source of biomass for most of the year, especially in winter. In the breeding season, pairs in heavily forested areas captured more squirrels and less rabbits than those in lightly forested areas. Changes in the diet involving a decrease in rabbit consumption and an increase in the proportion of red-legged partridge were detected following a rabbit population crash caused by the viral haemorrhagic disease. -Author
Article
Although studies of bald eagle (Haliaeetus leucocephalus) food habits are numerous, few authors have quantified biases inherent in the techniques used. In our study of food habits of nonbreeding bald eagles on the northern Chesapeake Bay, we examined biases associated with pellet analysis, food remains analysis, and direct observation. We assessed these biases through controlled feedings of 2 captive bald eagles and through observations of free-ranging eagles. Fish fed to 2 captive bald eagles were underrepresented (P < 0.001) in egested pellets. Most bird and mammal food items were detected in ≥1 pellet; however, species and carcass condition affected frequency of occurrence. Analysis of captive eagles' food remains overrepresented birds, medium-sized mammals, and large bony fish (P < 0.001); small mammals and small fish were underrepresented (P < 0.001). This bias increased over time due to greater persistence of some remains in shoreline plots. Direct observations of free-ranging eagles resulted in biases toward easily identified species such as eels and catfish, but also documented the use of small, soft-bodied fish, which were not well documented by the other techniques. Because of the variety of biases present, accurate assessment of bald eagle foods requires use of multiple techniques.