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449
Revista Chilena de Historia Natural
75: 449-461, 2002
INTRODUCTION
Raptors are at the end of a series of energy trans-
fers along food chains, from the primary producers
up to several organisms that prey on each other.
Being a top predator does not guarantee an easy
existence. The likelihood that raptors will become
prey of other predators is low, but their prey is not
easy to catch. Those that are easily caught may be
REVIEW
The raptors of Torres del Paine National Park, Chile: biodiversity and
conservation
Las rapaces del Parque Nacional Torres del Paine, Chile: biodiversidad y
conservación
FABIAN M. JAKSIC1, J. AGUSTÍN IRIARTE2 & JAIME E. JIMÉNEZ3
1Center for Advanced Studies in Ecology & Biodiversity, Pontificia Universidad Católica de Chile,
Casilla 114-D, Santiago, Chile; fjaksic@genes.bio.puc.cl
2Departamento de Protección de Recursos Naturales Renovables, Servicio Agrícola y Ganadero,
Avenida Bulnes 140, Santiago, Chile
3Laboratorio de Ecología, Universidad de Los Lagos, Casilla 933, Osorno, Chile
ABSTRACT
Fifteen raptor species (Falconiformes and Strigiformes) breed and other two may breed in Torres del Paine National
Park (Chilean Patagonia), the highest raptor species richness documented in Chile. Accounts for each raptor species
in Torres del Paine are provided, including information on weight, habitat, diet, residence, conservation, and
miscellaneous observations in the Park. We compare raptor species richness in Torres del Paine with well studied
localities in central and northern Chile, and speculate on causes for the higher raptor diversity observed in the Park.
Raptor macroniches in Torres del Paine are assessed, describing primarily their use of two major habitat types and nine
food resources. We examine food-niche relationships for a subset of four mammal-eating raptors, in light of their
different ecologies and body sizes. A monitoring program for raptors in Torres del Paine is proposed, under the rationale
that these indicator species may help foresee impending disruptions of basic ecosystem processes that determine the
relatively pristine conditions still prevailing in the Park.
Key words: Falconiformes, Strigiformes, Chile, Patagonia, diet, weight, habitat use, niche relationships.
RESUMEN
Quince especies de rapaces (Falconiformes y Strigiformes) se reproducen y otras dos posiblemente se reproducen en
el Parque Nacional Torres del Paine (Patagonia chilena), la mayor riqueza de especies de rapaces documentada hasta
ahora en Chile. Entregamos descripciones de cada especie de rapaz en Torres del Paine, incluyendo información sobre
peso, hábitat, dieta, residencia, conservación, y observaciones misceláneas en el Parque. Comparamos la riqueza de
especies de rapaces en Torres del Paine con aquella en localidades bien estudiadas del centro y norte de Chile, y
especulamos sobre las causas de la mayor diversidad de rapaces observadas en el Parque. Determinamos los
macronichos de las rapaces en Torres del Paine, describiendo principalmente su uso de dos tipos de hábitats
predominantes y de nueve tipos de recursos alimentarios. Examinamos las relaciones de nicho trófico en un conjunto
de cuatro rapaces consumidoras de micromamíferos, a la luz de sus diferentes ecologías y tamaños corporales.
Esbozamos un programa de monitoreo para las rapaces de Torres del Paine, bajo el criterio que estas especies
indicadoras pueden ayudar a prever posibles disfunciones de los procesos ecosistémicos básicos que determinan las
condiciones relativamente prístinas aún prevalentes en el Parque.
Palabras clave: Falconiformes, Strigiformes, Chile, Patagonia, dieta, peso, uso del hábitat, relaciones de nicho.
weakened by parasites, diseases, and toxins that
may in turn decrease the raptors’ fitness (that is,
their survival compounded by reproductive suc-
cess). Raptors are indeed a sink into which all
ailments of an ecosystem pour, sooner or later. If
poison is applied to control “vermin species,” such
as rabbits or hares, it may be ingested and may
eventually kill a raptor that was contributing to
keeping the vermin’s population in check, thus
450 JAKSIC ET AL.
only fueling more massive poisoning campaigns
into a never-ending spiral. Insecticides such as
Dichloro Diphenyl Tricloroethane (DDT) are still
ilegally used in Chile to control insect pests in
agricultural areas. After a short transit through
insectivorous birds or small mammals these dan-
gerous insecticides become concentrated in raptor
tissues (Mendelhall & Pank 1980, Townsend et al.
1981), thus altering the fragile predator-prey equi-
librium. Even lead used for shooting game birds
quickly migrates through the food chain up to
raptors. Thus, raptors are valuable and sensitive
indicators of an ecosystem’s health.
Because raptors are large and conspicuous (at
least, the diurnal ones), it is relatively easy to
measure their abundance and reproductive suc-
cess, thus providing early warnings about dete-
riorating processes that may be affecting the eco-
system. But in order for raptors to become a
precise environmental gauge, a full understand-
ing must be gained of their interactions with their
prey and among themselves. This begins by as-
sessing when and where in a particular site they
occur, what they eat, and how they interact. Torres
del Paine National Park in southernmost Chile,
offers a unique opportunity to use raptors as envi-
ronmental indicators because it is a relatively pris-
tine area. Our aim in this paper, apart from bring-
ing together what is known about the Park’s rap-
tors, is to set a baseline, so that future changes may
be gauged in a monitoring program yet to be started.
MATERIAL AND METHODS
This paper is based on a review of the relevant
literature on Torres del Paine National Park, and
on our collective experience. Major literature
sources consulted were: Pisano (1974), for veg-
etation characteristics of the Park; Humphrey et
al. (1970) and C. Venegas (personal communica-
tion), for raptor weights; Johnson (1965, 1967),
Markham (1971), Venegas & Jory (1979), and
Venegas (1982), for raptor distributions;
Humphrey et al. (1970) and Vuilleumier (1985),
for raptor habitats and residence status; Jaksic &
Jiménez (1986a), for raptor conservation status;
many sources clearly identifiable by their titles in
the bibliography section, for raptor diets; and
Iriarte et al. (1990), for raptor niche relation-
ships. It should be noted that our own field expe-
rience sometimes contradicts the literature sources
consulted.
We recognize three major habitat types used by
raptors, but only two of these stand from a botani-
cal viewpoint: Forest includes the Park’s dense
deciduous forests dominated by Nothofagus
antarctica and N. pumilio (which represent less
than 20 % of the surface area of the Park; Iriarte et
al. 1990). Open country is composed of both dwarf
shrublands dominated by Mulinum spinosum and
Verbena tridens, and grasslands dominated by
Festuca spp. and Anarthrophyllum patagonicum.
Open country comprises about 80 % of the Park’s
surface (Iriarte et al. 1990). The third habitat type
important for raptors is woodlands, which we de-
fine as an open-canopy successional forest with a
scrub understory, an ecotone between the two major
vegetation formations already described. A fourth
habitat type might have been considered: cliffs,
but surely they are not used as hunting areas by
raptors but rather as nesting and roosting sites.
We placed resident raptors in three categories:
year-round residents, which breed and overwin-
ter in the Park; breeding migrants, which breed in
the Park but migrate out of the area to winter in
milder regions; and partial migrants, which breed
in the Park, but on arrival of winter conditions
may migrate out or stay put (i.e., part of the
population leaves and another part remains). It
was not always easy to classify raptors into one or
the other of these three categories. Those labeled
“likely” are based on little more than educated
guesses. We have used a few abbreviations for
descriptions of gender and age of raptors: M
(male), F (female), U (unsexed), A (adult), and I
(immature). Unless otherwise stated, all records
and observations are from the Park itself or from
the Magallanes Region, where the Park is placed.
Finally, vertebrate nomenclature follows Veloso
& Navarro (1988) for amphibians, Núñez & Jaksic
(1992) for reptiles, Del Hoyo et al. (1994, 1999)
for raptorial birds, Araya et al. (1995) for non-
raptorial birds, and Tamayo et al. (1987) for mam-
mals.
RAPTOR SPECIES ACCOUNTS
Andean condor (Vultur gryphus Linnaeus 1758,
Cathartidae)
Weight: F 7,500 g (C. Venegas, personal commu-
nication). Habitat: cliffs. Diet: obviously the con-
dor is a scavenger of relatively large mammals,
and may attack newborn sheep during the lamb-
ing season. We once baited condors with a dead
sheep for filming purposes and 17 birds arrived.
William L. Franklin’s film “The Guanaco in
Patagonia” shows a condor feeding on a newborn
guanaco. J. Behl (personal communication) has
seen condors feeding on guanaco carcasses on at
least six occasions. Residence: confirmed year-
round resident (see also Couve & Vidal 1999,
451RAPTORS OF TORRES DEL PAINE
Matus & Barría 1999, Sarno et al. 2000). Conser-
vation Status in Magallanes region: unknown.
Conservation Status in Chile: vulnerable accord-
ing to both Glade (1988) and Rottmann & López-
Callejas (1992).
Bicolored hawk (Accipiter bicolor Vieillot 1817,
Accipitridae)
Weight: IM 227 g, IF 383 g, AU 425 g (Humphrey
et al. 1970); F 275 g, F 370 g, F 414 g, F 415 (C.
Venegas personal communication). Habitat: forest
(sometimes woodland), in flat or rolling terrain.
Diet: Humphrey et al. (1970) reported two prey
species from Tierra del Fuego: thorn-tailed rayadito
(Aphrastura spinicauda Gmelin 1789) and eared
dove (Zenaida auriculata des Murs 1847). Resi-
dence: likely breeding migrant; C. Venegas (per-
sonal communication) is of the opinion that this
species is, at best, occasional, but Couve & Vidal
(1999) and Matus & Barría (1999) consider it as a
year-round resident. Other observations: we have
not seen this accipiter, but its presence might be
expected on account of its geographic distribution
and habitat selection. Conservation Status in
Magallanes region: threatened by reduction of its
preferred habitat for breeding and feeding (old-
growth forests), and by shooting (Jaksic & Jiménez
1986a). Conservation Status in Chile: rare accord-
ing to both Glade (1988) and Rottmann & López-
Callejas (1992).
Black-chested eagle (Geranoaetus melanoleucus
Vieillot 1819, Accipitridae)
Weight: AM 2,698 g, AF 3,033 g, AF 2,381 g
(Humphrey et al. 1970); M 2,300 g, M 2,315 g, F
2,225 g, F 3,025 g (C. Venegas personal commu-
nication). Habitat: ecotone between forest and
open country, in flat, rolling, or rugged terrain
(Jiménez & Jaksic 1989, 1990). Diet: Iriarte et al.
(1990) found that 91 % of prey were European
hares (Lepus europaeus Linnaeus 1758), 6 %
other mammals, and 3 % birds. Jiménez & Jaksic
(1990) reported 82 % European hares and 18 %
birds. Humphrey et al. (1970) reported goslings
(Chloephaga sp.) as prey in Tierra del Fuego.
Residence: confirmed year-round resident (see
also Couve & Vidal 1999, Matus & Barría 1999).
Other observations: Iriarte et al. (1990) reported
five nests on top of tall Nothofagus sp. in the
northern part of the Park. Jiménez & Jaksic (1990)
reported 13 nests on cliffs near Administración,
Portería, Laguna Amarga, and Laguna de los
Cisnes. Conservation Status in Magallanes: of no
conservation concern at present, because prey
availability has increased due to the introduction
in 1896, and subsequent population irruption of
the European hare (Grigera & Rapoport 1983),
and to increased edge habitat between forest and
open country caused by forest clearing (Jaksic &
Jiménez 1986a). Conservation Status in Chile:
not listed as threatened by either Glade (1988) or
by Rottmann & López-Callejas (1992).
Red-backed hawk (Buteo polyosoma Quoy &
Gaimard 1824, Accipitridae)
Weight: AM 1,134 g, AM 1,134 g, AM 992 g, IF
1,417 g (Humphrey et al. 1970); M 856 g, M 950
g, M 1,105 g, M 1,258 g, F 1,265 g, F 1,372 g (C.
Venegas, personal communication). Habitat: eco-
tone between forest and open country, in flat,
rolling, or rugged terrain (Jiménez 1995). Diet:
Humphrey et al. (1970) reported Ctenomys
magellanicus Bennett 1835 (Magellan tuco-tuco)
as prey in Tierra del Fuego. Residence: confirmed
partial migrant. Couve & Vidal (1999) consider it
as an infrequent visitor to the Park, whereas Matus
& Barría (1999) consider it a year-round resident.
Other observations: we have seen this buteo on
few occasions only, near Portería; once we saw an
individual chased by a black-chested eagle. Con-
servation Status in Magallanes: threatened by
reduction of presumable staple prey (Magellan
tuco-tuco), caused by sheep trampling this fosso-
rial rodent’s burrows (Jaksic & Jiménez 1986a).
However, F. Vuilleumier (personal communica-
tion) does not believe this to be the case in Tierra
del Fuego. Conservation Status in Chile: not listed
as threatened by either Glade (1988) or by
Rottmann & López-Callejas (1992).
Rufous-tailed hawk (Buteo ventralis Gould 1837,
Accipitridae)
Weight: M 1,031 g, M 1,175 g, F 1,195 g, F 1,410
g, U 1,735 g (C. Venegas, personal communi-
cation). Habitat: probably in forest and ecotone
with open country, in flat or rolling terrain. Diet:
Humphrey et al. (1970) reported an unidentified
rodent as prey in Tierra del Fuego. One of us (J.
Jiménez) has seen this species hunting for Chil-
ean pigeon (Columba araucana Lesson 1827)
near Valdivia and preying on birds and mammals
in Temuco. Residence: likely year-round resident
(in line with Matus & Barría 1999). Nevertheless,
Couve & Vidal (1999) do not list this species as
present in the Park. Other observations: we have
not seen this buteo, but its presence might be
452
expected on account of its geographic distribu-
tion and habitat selection. Garay & Guineo (1993)
published a picture supposedly of this hawk from
the Park, but in fact it corresponds to a juvenile
black-chested eagle (Vuilleumier 1997: 211).
According to F. Vuilleumier (personal communi-
cation) this species is definitely rare in
Magallanes. Conservation Status in Magallanes:
unknown (Jaksic & Jiménez 1986a). Conserva-
tion Status in Chile: rare according to both Glade
(1988) and Rottmann & López-Callejas (1992).
Cinereous harrier (Circus cinereus Vieillot 1816,
Accipitridae)
Weight: AM 354 g, AF 482 g, IM 340 g (Humphrey
et al. 1970); AM 320 g, AF 510 g (Jiménez &
Jaksic 1988); M 315 g, M 359 g, F 427 g, F 475 g
(C. Venegas personal communication). Habitat:
open country near marshes, in flat or rolling
terrain. Diet: Jiménez & Jaksic (1988) documented
its diet as consisting of 19 % mammals, 27 %
birds, 19 % reptiles, and 35 % arthropods.
Humphrey et al. (1970) reported unidentified
rodents and “green lizards” (most likely,
Liolaemus magellanicus Hombron & Jacquinot
1847) as prey in Tierra del Fuego. Residence:
confirmed migrant (either breeding migrant or
partial migrant). Similarly, Couve & Vidal (1999)
consider it as a summer visitor that breeds in the
Park, but Matus & Barría (1999) consider it as a
likely resident. Thus, the residence status of this
harrier requires further study. Other observations:
abundant only around the small lagoons close to
the Portería (where it nests), and less frequently
between Portería and Laguna de los Cisnes.
Conservation Status in Magallanes: of no
conservation concern at present, because the
apparent reduction in one of its staple prey, the
lizard L. magellanicus (see Jaksic & Schwenk
1983) has been compensated by increased habitat
availability (and hence also increased prey)
brought about by the clearing of forests (Jaksic &
Jiménez 1986a). Conservation Status in Chile:
not listed as threatened by either Glade (1988) or
by Rottmann & López-Callejas (1992).
Chimango caracara (Milvago chimango Vieillot
1816, Falconidae)
Weight: AF 482 g (Humphrey et al. 1970); M 356
g, M 357 g, M 375 g, M 380 g, M 395 g, F 355 g,
F 365 g, F 390 g, F 400 g, U 295 g (C. Venegas
personal communication). Habitat: open country,
in flat or rolling terrain. Diet: Humphrey et al.
(1970) reported that on Tierra del Fuego this
caracara is a scavenger but occasionally eats in-
sects. Residence: confirmed breeding migrant.
Nevertheless, Couve & Vidal (1999) and Matus &
Barría (1999) consider it as a year-round resident.
Other observations: not abundant, seen most fre-
quently near Portería; one pair was seen nesting
in the marsh nearby, among harriers (Circus
cinereus). Conservation Status in Magallanes: of
no conservation concern at present (Jaksic &
Jiménez 1986a). Conservation Status in Chile:
not listed as threatened by either Glade (1988) or
by Rottmann & López-Callejas (1992).
White-throated caracara (Phalcoboenus
albogularis Gould 1837, Falconidae)
Weight: AM 808 g, IU 765 g (Humphrey et al.
1970). Habitat: forest and woodland, in flat, roll-
ing, or rugged terrain. Diet: this raptor is likely a
scavenger. Residence: likely year-round resident
(see also Matus & Barría 1999). Our assessment
differs from that of C. Venegas (personal commu-
nication), who opines that this species is only
occasional, and that of Couve & Vidal (1999) who
consider it as an yearly visitor to the Park (breed-
ing migrant?). Other observations: not abundant.
One of us (J. Jiménez) once saw one of these
caracaras scavenging on a sheep in a grassland.
Conservation Status in Magallanes: unknown
(Jaksic & Jiménez 1986a). Conservation Status in
Chile: not listed as threatened by either Glade
(1988) or by Rottmann & López-Callejas (1992).
But according to F. Vuilleumier (personal commu-
nication) this species is probably threatened, as is
rare in Magallanes (including Tierra del Fuego and
Navarino areas).
Crested caracara (Polyborus plancus Miller 1777,
Falconidae)
Weight: AM 1,460 g (Humphrey et al. 1970); M
1,266 g, M 1,340 g, F 1,295 g, F 1,340 g, F 1,350
g, F 1,385 g (C. Venegas personal communica-
tion). Habitat: open country, in flat or rolling
terrain. Diet: Humphrey et al. (1970) reported
that on Tierra del Fuego it is a scavenger, that
they saw one caracara eating a goose egg
(Chloephaga sp.), and that they found a roosting
place with an accumulation of bones of Magellan
tuco-tucos (Ctenomys magellanicus). In Torres
del Paine crested caracaras scavenge mainly on
guanacos and European hares (Engh et al. 1997).
J. Behl (personal communication) has seen them
feeding on guanaco carcasses and preying on
JAKSIC ET AL.
453
hatchlings of lesser rhea (Pterocnemia pennata
d’Orbigny 1834). Residence: confirmed year-
round resident (see also Couve & Vidal 1999,
Matus & Barría 1999). Other observations: com-
mon in open habitats, particularly between Lago
Sarmiento and Lago Nordenskjold. This caracara
congregates in large numbers (20-30 individuals)
at carcasses. We have seen it scavenge on Euro-
pean hares killed by motor vehicles on Park roads.
We saw nests of this species on top of Nothofagus
antarctica (ñirre) 4-5 m tall, near water. Conser-
vation Status in Magallanes: of no conservation
concern at present, despite being heavily hunted,
because of increased food availability (carcasses)
caused by roadkills of the abundant European
hare, and by poorly managed sheep operations
(Jaksic & Jiménez 1986a). Conservation Status in
Chile: not listed as threatened by either Glade
(1988) or by Rottmann & López-Callejas (1992).
Peregrine falcon (Falco peregrinus Tunstall 1771,
Falconidae)
Weight: AF 1,035 g, AU 1,049 g (Humphrey et al.
1970); F 995 g, F 1,005 g, F 1,160 g, F 1,185 g (C.
Venegas personal communication). Habitat: open
country, in flat or rolling terrain. Diet: McNutt
(1981) reported over 20 bird species as prey else-
where in Magallanes. Residence: likely partial
migrant; C. Venegas (personal communication)
is of the opinion that this species is, at best,
occasional, but Couve & Vidal (1999) and Matus
& Barría (1999) consider it as a year-round resi-
dent. Other observations: one of us (J. Jiménez)
has seen this falcon only once, at Sierra del Toro,
and surprisingly it was a pallid, or “kreyenborgi”
morph (see Ellis & Péres-Garat 1983, McNutt
1984). Garay & Guineo (1993) published a pic-
ture supposedly of this falcon from the Park, but
in fact it corresponds to a juvenile cinereous
harrier (Vuilleumier 1997: 211). McNutt (1981)
described the hunting behavior of the falcon in
Tierra del Fuego. Conservation Status in
Magallanes: unknown (Jaksic & Jiménez 1986a).
According to F. Vuilleumier (personal communi-
cation) it is not common, and surely at risk.
Conservation Status in Chile: vulnerable accord-
ing to both Glade (1988) and Rottmann & López-
Callejas (1992).
Aplomado falcon (Falco femoralis Temminck
1822, Falconidae)
Weight: No data available. Habitat: open coun-
try, in flat or rolling terrain. Diet: Humphrey et al.
(1970) reported an unidentified bird as prey in
Tierra del Fuego. It is likely that it preys mainly
on birds and insects, as reported in central Chile
(Jiménez 1993). Residence: likely breeding mi-
grant. Our assessment should be taken cautiously
because two other authorities (C. Venegas, F.
Vuilleumier) differ in their opinion: for the former,
this species is a likely breeding migrant; for the
latter, it is merely accidental. Couve & Vidal
(1999) and Matus & Barría (1999) do not list this
species as present in the Park. Other observa-
tions: we have not seen this falcon, but F.
Vuilleumier (personal communication) saw one
adult bird near the Park on 26 February 1988.
Conservation Status in Magallanes: unknown
(Jaksic & Jiménez 1986a). Conservation Status in
Chile: not listed as threatened by Glade (1988),
but considered Insufficiently known by Rottmann
& López-Callejas (1992).
American kestrel (Falco sparverius Linnaeus 1758,
Falconidae)
Weight: AM 156 g, AF 142 g (Humphrey et al.
1970); M 130 g, F 140 g, F 154 g, F 155 g, F 163
(C. Venegas personal communication). Habitat:
open country, in flat or rolling terrain. Diet:
Humphrey et al. (1970) reported that in Tierra del
Fuego it preys on small birds, including house
wrens (Troglodytes aedon Vieillot 1809), lizards
(likely, Liolaemus magellanicus), beetles (Co-
leoptera), and midges (Diptera). Residence: likely
breeding migrant. Couve & Vidal (1999) and
Matus & Barría (1999) consider it as a year-round
resident. Other observations: we have not seen
this small falcon, but J. Behl (personal communi-
cation) has confirmed sightings and photos of this
bird in the Park. McNutt (1984) described the
breeding behavior of this falcon in Tierra del
Fuego. Conservation Status in Magallanes: of no
conservation concern at present. Conservation
Status in Chile: not listed as threatened by either
Glade (1988) or by Rottmann & López-Callejas
(1992).
Common barn owl (Tyto alba Scopoli 1769,
Tytonidae)
Weight: M 259 g, M 383 g (sic), F 295 g, F 305 g,
F 310 g (C. Venegas personal communication).
Habitat: open country, in flat or rolling terrain.
Diet: Iriarte et al. (1990) reported that its diet is
made up entirely of rodents. Humphrey et al. (1970)
reported beetles (Coleoptera) and mice (Roden-
tia) as prey in Tierra del Fuego. Residence: likely
RAPTORS OF TORRES DEL PAINE
454
year-round resident or at least breeding migrant.
Couve & Vidal (1999) consider it as a year-round
resident, and Matus & Barría (1999) consider it as
a likely resident. Other observations: we saw
nests of two pairs on cliffs near Laguna Amarga.
Conservation Status in Magallanes: unknown
(Jaksic & Jiménez 1986a). Conservation Status in
Chile: not listed as threatened by either Glade
(1988) or by Rottmann & López-Callejas (1992).
Magellan horned owl (Bubo magellanicus Gmelin
1788, previously known as Bubo virginianus
Gmelin 1788, Strigidae)
Weight: M 940 g, M 1,074 g, F 1,335 g, U 1,015 g (C.
Venegas personal communication). Habitat: eco-
tone between forest and open country, in flat, roll-
ing, or rugged terrain. Diet: quantitative information
has been reported by Jaksic et al. (1978), Rau et al.
(1978), Yáñez et al. (1978) and Rau & Yáñez (1981).
Jaksic et al. (1986) summarized these reports as
follows: 1 % European hares, 87 % rodents, 2 %
birds, and 10 % insects. In contrast, Iriarte et al.
(1990) found that diet was comprised of 17 % Euro-
pean hares, 79 % rodents, and 4 % birds. The dis-
crepancy in the incidence of European hares in the
owl’s diet may be attributed to increased abundance
of hares in the 10 years elapsed between the two
studies. However, J. Rau (personal communication)
has unpublished data showing that hares have not
clearly increased over the years, and he thinks that
reduced abundance of native rodents such as
Reithrodon physodes Olfers 1818 may better ex-
plain the shift of Magellan horned owls toward
European hares—an alternative prey. Residence:
confirmed year-round resident (see also Couve &
Vidal 1999 and Matus & Barría 1999). Other obser-
vations: we saw two active nests on top of Nothofagus
sp. trees at an ecotone between forest and grassland
near the Administración; we have seen this owl
perching on cliffs between Portería and Laguna
Amarga, and also near Laguna Lazo. Conservation
Status in Magallanes: of no conservation concern at
present, because of increased favorable habitat (edge
between forest and open country) and increased prey
availability in the form of European hares (Jaksic &
Jiménez 1986a). Conservation Status in Chile: not
listed as threatened by either Glade (1988) or by
Rottmann & López-Callejas (1992).
Austral pygmy owl (Glaucidium nanum King 1828,
Strigidae)
Weight: AM 73 g, AM 73 g, AF 62 g, AF 83 g
(Humphrey et al. 1970); M 55 g, F 71 g, F 75 g (C.
Venegas, personal communication). Habitat: for-
est and woodland, in flat or rolling terrain. Diet:
Humphrey et al. (1970) reported small birds and
small rodents as prey in Tierra del Fuego. Resi-
dence: confirmed partial migrant. Couve & Vidal
(1999) and Matus & Barría (1999) consider it as
a year-round resident. Other observations: one of
us (J. Jiménez) has seen this small owl twice,
once in the Administración area, another close to
the Paine Towers. This owl may be more abun-
dant at the Park than suggested by these few
sightings. Conservation Status in Magallanes:
unknown (Jaksic & Jiménez 1986a). According to
F. Vuilleumier (personal communication), this
species is not common, and localized, in
Magallanes. Conservation Status in Chile: not
listed as threatened by either Glade (1988) or by
Rottmann & López-Callejas (1992).
Short-eared owl (Asio flammeus Pontoppidan
1763, Strigidae)
Weight: AM 425 g (Humphrey et al. 1970); M 450
g (C. Venegas, personal communication). Habi-
tat: open country close to marshes, in flat or
rolling terrain. Diet: it should not differ markedly
from that reported by Rau et al. (1992) and by
Martínez et al. (1998) near Osorno and Valdivia,
i.e., consisting chiefly of rodents. Residence:
confirmed breeding migrant or partial migrant.
Matus & Barría (1999) consider it as a likely
resident, Guineo (1999) lists it as present, whereas
Couve & Vidal (1999) do not list this species as
present in the Park. Other observations: although
we did not see this bird, One of us (J. Jiménez)
collected three pellets with typical owl features
(high bone/fur ratio) at the marsh near the Portería,
that contained unidentified rodents. Conserva-
tion Status in Magallanes: of no conservation
concern at present (Jaksic & Jiménez 1986a).
Conservation Status in Chile: insufficiently known
according to both Glade (1988) and Rottmann &
López-Callejas (1992).
Rufous-legged owl (Strix rufipes King 1828,
Strigidae)
Weight: 380-420 (D. R. Martínez, personal com-
munication). Habitat: forest, in flat or rolling ter-
rain. Diet: it should not differ markedly from that
observed by Martínez & Jaksic (1996, 1997) near
Valdivia and Chiloé, i.e., consisting of rodents and
insects. Residence: confirmed year-round resident.
Matus & Barría (1999) consider it as a likely
resident, and Guineo (1999) lists it as present, but
JAKSIC ET AL.
455
Couve & Vidal (1999) do not list this species as
present in the Park. Observations: although we did
not see these birds, we heard their calls near Lago
Grey and near the Paine Towers. Conservation
Status in Magallanes: threatened by reduction of
preferred habitat for breeding and feeding, i.e.,
old-growth forests (Jaksic & Jiménez 1986a). Con-
servation Status in Chile: insufficiently known
according to Glade (1988), and vulnerable accord-
ing to Rottmann & López-Callejas (1992).
RAPTOR SPECIES RICHNESS
The richness of raptor species in the Park is
remarkably high by Chilean, American, and Eu-
ropean standards (Table 1, Jaksic et al. 1990,
Marti et al. 1993, Jaksic 1998). When considering
permanent resident species only, Torres del Paine
exceeds in raptor richness four other relatively
well studied sites in Chile: Río Clarillo National
Reserve (Díaz et al. 2002) and San Carlos de
Apoquindo, both mediterranean-climate evergreen
scrub sites near Santiago (Jaksic & Delibes 1987,
Jaksic 2001, Jaksic et al. 2001), Las Chinchillas
National Reserve at Aucó, a semi-arid thorn scrub
site near Illapel (Jaksic et al. 1992, 1996), and
Fray Jorge National Park, a semi-arid thorn scrub
site with a milder climate than Aucó, near La
Serena (Jaksic et al. 1993, 1997). It should be
noted, though, that Torres del Paine is over an
order of magnitude larger (241,241 ha) than Río
Clarillo National Reserve (10,185 ha), San Carlos
de Apoquindo (835 ha), Las Chinchillas National
Reserve (4,229 ha), and Fray Jorge National Park
(9,959 ha).
In addition to larger size, greater habitat hetero-
geneity may account for the more diverse raptor
fauna at Torres del Paine: the presence of marshes
clearly permits the residency of cinereous harriers
and short-eared owls, and dense forest stands al-
low the presence of bicolored hawks and rufous-
legged owls. Further, there is a geographic factor
involved as well, because of the extremely south-
TABLE 1
Richness in species of raptors in four sites of Chile. See text for definition of resident status and
for geographic location of the sites; (+) = permanent presence, (-) = absence, (?) = presence
suspected, (±) = occasional presence. Localities are arranged from south (left) to north (right)
Riqueza de especies de rapaces en cuatro sitios de Chile. Véase el texto para la definición del estatus de residencia y
para localización geográfica de los sitios; (+) = presencia permanente, (-) = ausencia, (?) = presencia presunta, (±) =
presencia ocasional. Localidades dispuestas de sur (izquierda) a norte (derecha)
Raptor species Torres Río San Aucó Fray
Paine Clarillo Carlos Jorge
Andean condor (Vultur gryphus) ++++-
Turkey vulture (Cathartes aura)-+±--
Bicolored hawk (Accipiter bicolor)+-±--
Black-chested eagle (Geranoaetus melanoleucus) +++++
White-throated hawk (Buteo albigula)--+--
Red-backed hawk (Buteo polyosoma) +++++
Rufous-tailed hawk (Buteo ventralis) ?----
Harris’ hawk (Parabuteo unicinctus) -++++
Cinereous harrier (Circus cinereus)+±±-±
White-tailed kite (Elanus leucurus)-+±-±
Chimango caracara (Milvago chimango)+++±+
White-throated caracara (Phalcoboenus albogularis)+ ---
Andean caracara (Phalcoboenus megalopterus)-++--
Crested caracara (Polyborus plancus) +----
Peregrine falcon (Falco peregrinus)+++-±
Aplomado falcon (Falco femoralis)?-±+±
American kestrel (Falco sparverius) +++++
Common barn owl (Tyto alba) +++++
Magellan horned owl (Bubo magellanicus) +++++
Austral pygmy owl (Glaucidium nanum) +++++
Burrowing owl (Athene cunicularia) - -+++
Short-eared owl (Asio flammeus)+-±--
Rufous-legged owl (Strix rufipes) ++---
Total resident raptors 15 (17?) 14 (15?) 13 (19?) 10 (11?) 9 (13?)
RAPTORS OF TORRES DEL PAINE
456
erly location of Torres del Paine. The absence of
raptors that are characteristic of central and north-
ern Chile, such as Harris’ hawk (Parabuteo
unicinctus Temminck 1824) and white-tailed kite
(Elanus leucurus Vieillot 1818) is related to their
more northerly distribution centers. The Harris’
hawk does not occur farther south than 44° S, and
the black-shouldered kite does not occur farther
south than 42° S (Jaksic & Jiménez 1986a, see also
Venegas & Drouilly 1972).
On the other hand, rufous-tailed hawks and
white-throated caracaras have their main distri-
bution area in the southern part of Chile, the
rufous-tailed hawk not reaching farther north than
36° S, and the white-throated caracara, 44° S
(Jaksic & Jiménez 1986a). This distributional
fact accounts for their absence in the central and
northern study areas. Similarly, although crested
caracaras are distributed over an extensive latitu-
dinal range in Chile, they are nowhere abundant
except in the southern part of the country (Jaksic
& Jiménez 1986a). Conversely, although burrow-
ing owls (Athene cunicularia Molina 1782) are
also extensively distributed in Chile, they appear
to have been extirpated from Magallanes in his-
torical times. According to Humphrey et al. (1970:
240-241), the disappearance of this owl from
Tierra del Fuego around 1920 was “somehow
related to the increase in numbers of sheep and
other livestock...” Apparently, sheep trampled
out the preferred prey of these owls (Magellan
tuco-tuco), as well as their burrows. Some au-
thorities have been entertaining the idea of rein-
troducing this owl to its former range, now that
livestock activities are less intense than in the
past (Venegas & Sielfeld 1998: 72).
Finally, it is worth noting that Johnson et al.
(1990), when discussing the high mammalian spe-
cies richness of the area where Torres del Paine is
located, stated: “In conclusion, there are two major
reasons why the northern Chilean Patagonia has a
high diversity of mammalian fauna and is the
home of 38 species of mammals. First, is the great
variety of habitat types, and second, because the
zone serves as a link between two distinctive
biotas, the flat and dry Patagonian steppe on the
Argentine side, and the wet, Nothofagus forest of
the southern Chilean archipelago region.” We
tend to agree with this conclusion, although em-
phasizing the first reason over the second.
RAPTOR MACRONICHES
By macroniches we refer to how raptors are dis-
tributed along three niche dimensions: time, habi-
tat, and prey. Of the 17 raptor species probably
present in Torres del Paine (Table 1), 14 are
diurnal, a figure that includes all Falconiforms
and two owls that are quite active in daylight
(short-eared owl and austral pygmy owl). In addi-
tion, Magellan horned owls are also sometimes
active in daylight. The only strictly nocturnal
raptors at the Park are common barn owls and
rufous-legged owls.
Only four raptor species seem to be forest-
dwellers: bicolored Hawks, rufous-tailed hawks,
austral pygmy owls, and rufous-legged owls
(Table 2). All of these species are seen regularly
in woodlands, along the ecotones between the
forest and open country. The remaining 13 spe-
cies are edge or open-country dwellers. Iriarte et
al. (1990) sampled small mammals in scrub and
forest habitats of the Park, and found that trap-
ping success was only slightly higher in scrub
(0.63 captures trap-night-1) than in forest (0.52).
Indeed, trapping success was very low (only 0.06)
in the most open sites: grasslands. Obviously, the
numerical abundance of small mammals does not
explain why most raptors hunt in open country.
Perhaps an explanation is that even though small-
mammal abundance is similar between forest and
scrub, the vulnerability of small mammals is
higher in the more open country (and thus the
hunting success of the raptors). Of course, the
two raptors that prey most extensively on Euro-
pean hares, black-chested eagles and Magellan
horned owls, find this prey in high abundance
only in open country (Iriarte et al. 1990).
Out of the nine major prey resources recog-
nized in the Park, only one (amphibians) was not
exploited at all. At least two anuran species occur
in the Park (Markham 1971), the terrestrial toad
Bufo variegatus Gunther 1870 and the aquatic
frog Pleurodema bufonina Bell 1843. The frog
may be inaccessible for raptors, but the toad
should not be. However, Chilean raptors are known
to prey on toads only rarely. Of eight raptor
species whose diets were studied in San Carlos de
Apoquindo (Jaksic et al. 1981), only one, the
burrowing owl, consumed anurans and did so to a
very small extent (3 % of its prey by number). In
Aucó (Jaksic et al. 1992), out of eight raptor
species studied, only burrowing owls ate anurans
to any extent (1-9 % of its prey). And in Fray
Jorge (Jaksic et al. 1993), out of seven raptor
species monitored for food habits, again only the
burrowing owl took anurans as prey (0-13 %). It
is tempting to speculate that if burrowing owls
were present at Torres del Paine, they might be
exploiting this “unused” prey resource.
The remaining eight prey resources present at
the Park are probably exploited by one (only
peregrine falcons may be able to exploit medium-
JAKSIC ET AL.
457
sized birds) to nine raptor species (small-sized
mammals). High concentration of raptor preda-
tion on small- and medium-sized mammals has
also been reported in the central and northern
Chilean studies referred to above.
Torres del Paine has more scavenging raptors
than reported in other studies in Chile (Jaksic &
Jiménez 1986b), but a similar number to that
reported for Argentine Patagonia (Travaini et al.
1998). In the lowlands of central and northern
Chile, only chimango caracaras play a major scav-
enging role. In none of these sites are there many
large mammals (native or introduced) such as
guanacos or sheep, and even medium-sized mam-
mals such as European hares are not as common
as in Torres del Paine (Engh et al. 1997). Perhaps
the low availability of carrion in those sites is
insufficient to maintain a higher diversity of scav-
engers. Indeed, Simonetti et al. (1984) reported
high rates of disappearances of rodent carcasses
in San Carlos de Apoquindo, and noted that in
addition to local predators, ants (Camponotus
spp.), carrion beetles (Trox bullatus), mouse opos-
sums (Thylamys elegans Waterhouse 1838,
Didelphidae), and Chilean racerunners
(Callopistes palluma Molina 1782, Teiidae) may
have disposed of carcasses quickly.
RAPTOR NICHE RELATIONSHIPS
Niche relationships refer to the way raptors co-
use one or more niche dimensions. Ideally, a
study of niche relationships should include quan-
tification of time, habitat, and prey use by sympa-
tric raptors. However, Jaksic et al. (1981) argued
that when different raptor species use the same
hunting habitat, independently of their activity
times, their food-niche relationships are the only
important aspect to be taken into account. This is
TABLE 2
Major food resources recognized, and where sought, by raptors in Torres del Paine. Scientific
names of raptor species are in Table 1
Recursos alimentarios reconocidos, y dónde son buscados, por las rapaces en Torres del Paine. Los nombres
científicos de las especies de rapaces están en la Tabla 1
Food resource In forest In open country
(1) Medium-sized mammals (hares, carnivores) None Black-chested eagle
Magellan horned owl
(2) Small-sized mammals (rodents) Rufous-tailed hawk Red-backed hawk
Austral pygmy owl Cinereous harrier
Rufous-legged owl American kestrel
Common barn owl
Magellan horned owl
Short-eared owl
(3) Medium-sized birds (ducks, ibises) None Peregrine falcon
(4) Small-sized birds (songbirds, doves) Bicolored hawk Aplomado falcon
Austral pygmy owl Cinereous harrier
Peregrine falcon
American kestrel
(5) Reptiles (lizards) None Cinereous harrier
American kestrel
(6) Amphibians (toads, frogs) None None
(7) Arthropods (insects, spiders) Austral pygmy owl Aplomado falcon
Cinereous harrier
Chimango caracara
American kestrel
(8) Oligochaetes (earthworms) None Chimango caracara
White-throated caracara
(9) Carrion None Andean condor
Chimango caracara
Crested caracara
White-throated caracara
RAPTORS OF TORRES DEL PAINE
458
what Iriarte et al. (1990) did in their dietary
analyses of four broadly sympatric raptor species
in Torres del Paine: black-chested eagle, cinere-
ous harrier, common barn owl, and Magellan
horned owl.
Although these four species represent only half
the number of raptor species that hunt for me-
dium- and small-sized mammals in open country
at the Park (Table 2), the study of Iriarte et al.
(1990) contributed important insights on how
mammal-eating raptors may interact with each
other. Using a measurement of diet similarity,
Iriarte et al. (1990) found that cinereous harriers
were the most divergent raptors in the use of prey
resources. Diet similarity with black-chested
eagles, Magellan horned owls, and common barn
owls was 31, 52, and 50 %, respectively. These
figures are low compared to central Chilean stud-
ies (Jaksic et al. 1981, Jaksic & Delibes 1987).
The apparent reason is that cinereous harriers are
relatively small in body mass (mean = 398 g, n =
9) and are omnivorous hunters, eating not only
small mammals but also birds, lizards, insects,
and arachnids. There is also some degree of habi-
tat separation between this harrier and the re-
maining three raptor species, because the harrier
forages mostly near marshes.
Black-chested eagles in turn have low diet simi-
larity with Magellan horned owls and common
barn owls (51 and 5 %, respectively). This is
because eagles appear to feed almost exclusively
on European hares (over 91 % of their diet by
numbers, even higher by biomass). The large
body mass (mean = 2,568 g, n = 7) and large size
of the talons of these eagles may facilitate their
killing of the relatively large hare (over 2,000 g).
The species with the most similar diets were the
Magellan horned and common barn owls (82 %
similarity), a percentage about twice as large as
that reported for central Chile (Jaksic et al. 1981,
Jaksic & Delibes 1987). Their diets were similar
even to the point of relative incidences of prey,
and differed only because Magellan horned owls
preyed on hares. This finding is not surprising, as
in central Chile Jaksic & Yáñez (1980) observed
the same divergence between these two owls in
their use of the relatively large European rabbit
(Oryctolagus cuniculus Linnaeus 1758, 1,300 g).
The larger body mass (1,091 g, n = 4) and talons
of Magellan horned owls compared to common
barn owls (310 g, n = 5) may account for this only
difference in prey composition in the Park.
In summary, the relatively large European hare
appears with higher frequency in raptors’ diets
according to their increasing size, from common
barn owls and cinereous harriers, through
Magellan horned owls to black-chested eagles.
The former two species do not prey on hares at all,
the third preys on them to some extent, and the
latter to a large extent. One is left wondering what
were the food-niche relationships among these
three species before European hares were intro-
duced (Novaro et al. 2000).
CONCLUSIONS
Torres del Paine harbors a remarkably high num-
ber of raptor species. It is unfortunate that local
raptor populations have not been consistently
monitored during the Park recovery from exten-
sive clearing and overgrazing, while at the same
time being invaded by European hares and wit-
nessing a remarkable recovery of its guanaco
stocks. These “natural experiments” must have
left a mark on the ecology of raptors present at the
Park. It is not too late, though, to think about the
future changes that Torres del Paine will undergo,
by the action of natural or human agents, ex-
pected or unexpected.
We propose that a monitoring program be
started, focusing on several features of the rap-
tors’ life histories: (a) residence status and popu-
lation trends (including breeding success, migra-
tory movements, and mortality patterns); (b) habi-
tat use; (c) presumable effects of human distur-
bances (fires, tourism); (d) food habits as related
to prey abundances in different habitat types; and
(e) interrelationships among the raptor species
(including, but not limited to, competitive and
agonistic interactions).
The raptor monitoring should be based on a
stratified survey method using transects (Fuller &
Mosher 1981, 1987). Transects should be of a
standard width (determined by a pilot study),
stratified by habitat and proportional in length to
the amount of the three main habitats recognized
in the Park: deciduous forests, woodlands, and
open terrain. Monitoring should be conducted
using the same transects along established dirt
roads and/or trails once a year, both during breed-
ing and non-breeding seasons. During the former
season raptors are more conspicuous because of
their breeding behavior and vocalizations, and
during the latter because of the better visibility
afforded when deciduous trees shed their leaves.
Surveys should be conducted preferably by the
same park rangers or observers familiar with the
species, their vocalizations, and the terrain. Ob-
servers should move on foot or on horseback
along the transects at a relatively constant speed,
and record each individual raptor observed (fly-
ing or perched) or heard within the standard width.
This protocol, when standardized by the effort
JAKSIC ET AL.
459
used (e.g., km surveyed), will provide a means of
comparison of relative abundance by species,
habitat, season, and year, and may as well be
conducted while performing other activities, such
as guanaco counts or patrolling the Park.
This monitoring program could be easily imple-
mented and is cost-effective. The Program of
Sponsored Research in the System of Protected
Areas, launched by Chile’s Corporación Nacional
Forestal several years ago, should consider rating
this proposed program as a high priority, and
perhaps even actively encourage researchers into
starting it.
ACKNOWLEDGMENTS
We are grateful to Bill Franklin and Warren
Johnson for encouraging us to write this paper.
We thank David R. Martínez, Jaime Rau, Claudio
Venegas, and Francois Vuilleumier for reviewing
an earlier draft, and sharing with us their exper-
tise on Patagonian raptors. We are indebted to
two anonymous reviewers that made cogent criti-
cisms of our paper, and contributed to improve it.
Yerko Vilina supplied us with some difficult to
obtain literature. This research was funded by
grant FONDAP-FONDECYT 1501-0001 to the
Center for Advanced Studies in Ecology &
Biodiversity.
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RAPTORS OF TORRES DEL PAINE
Associate Editor: P. Ojeda
Received November 14, 2001; accepted February 28, 2002
