ArticlePDF Available

Vocalizations of the Guatemalan Pygmy-Owl (Glaucidium cobanense)

Authors:
  • Eisermann & Avendaño Bird Studies Guatemala

Abstract and Figures

The lowlands of the Isthmus of Tehuantepec separate the range of the Guatemalan Pygmy-Owl (Glaucidium cobanense), recognized as a species in modern owl taxonomy and resident in the highlands of southeastern Mexico, Guatemala, and Honduras, from the range of Mountain Pygmy-Owl (Glaucidium gnoma) in the Mexican highlands northwest of the isthmus. Here we document hitherto undescribed vocalizations of Guatemalan Pygmy-Owls in the Guatemala-Chiapas highlands. We recorded four different vocalization types of adults: (1) territorialtoot calls, (2)whiwhiwhicalls given by the female during nest-site establishment, (3) softtootcalls of the male near the nest, and (4) copulation calls. The territorialtootcalls of Guatemalan Pygmy-Owls differed from those of Mountain Pygmy-Owls in Mexico. The mean individual call rate of Guatemalan Pygmy-Owls was 3.460.5 notes/sec (n549 call series of six individuals), significantly higher than in Mountain Pygmy-Owls (1.9 60.3 notes/sec,n534 call series of eight individuals). This new evidence of vocal differences supports modern taxonomic separation of both taxa.
Content may be subject to copyright.
VOCALIZATIONS OF THE GUATEMALAN PYGMY-OWL
(GLAUCIDIUM COBANENSE)
KNUT EISERMANN
1
PROEVAL RAXMU Bird Monitoring Program, Coba´n, Alta Verapaz, Guatemala and
Apartado Postal 98 Perife´rico, 01011 Guatemala Ciudad, Guatemala
STEVE N.G. HOWELL
P.O. Box 423, Bolinas, CA 94924 U.S.A.
ABSTRACT.—The lowlands of the Isthmus of Tehuantepec separate the range of the Guatemalan Pygmy-Owl
(Glaucidium cobanense), recognized as a species in modern owl taxonomy and resident in the highlands of
southeastern Mexico, Guatemala, and Honduras, from the range of Mountain Pygmy-Owl (Glaucidium
gnoma) in the Mexican highlands northwest of the isthmus. Here we document hitherto undescribed
vocalizations of Guatemalan Pygmy-Owls in the Guatemala-Chiapas highlands. We recorded four different
vocalization types of adults: (1) territorial toot calls, (2) whiwhiwhi calls given by the female during nest-site
establishment, (3) soft toot calls of the male near the nest, and (4) copulation calls. The territorial toot calls
of Guatemalan Pygmy-Owls differed from those of Mountain Pygmy-Owls in Mexico. The mean individual
call rate of Guatemalan Pygmy-Owls was 3.4 60.5 notes/sec (n549 call series of six individuals), signif-
icantly higher than in Mountain Pygmy-Owls (1.9 60.3 notes/sec, n534 call series of eight individuals).
This new evidence of vocal differences supports modern taxonomic separation of both taxa.
KEY WORDS: Glaucidium gnoma; Glaucidium cobanense; Guatemalan Pygmy-Owl;Mountain Pygmy-Owl;
Northern Pygmy-Owl;vocalizations.
VOCALIZACIONES DE GLAUCIDIUM COBANENSE
RESUMEN.—Las tierras bajas del istmo de Tehuantepec aı´slan el a´ rea de distribucio´n de Glaucidium coba-
nense, reconocida como especie segu´n la taxonomı´a moderna de bu´hos y residente en las tierras altas de
Chiapas, Me´xico, Guatemala y Honduras, del a´rea de distribucio´n de Glaucidium gnoma en las tierras altas
de Me´xico al norte del istmo. Aquı´ documentamos vocalizaciones de Glaucidium cobanense de las tierras altas
de Guatemala y Chiapas que au´n no habı´an sido descritas. Cuatro diferentes vocalizaciones de adultos
fueron registradas: (1) llamado territorial, (2) serie de llamado vivivi de la hembra durante la fase de
establecimiento del sitio de anidacio´n, (3) llamado suave del macho cerca del nido, y (4) llamados de
copulacio´n. El llamado territorial de G. cobanense fue distinto del de G. gnoma del norte de Me´ xico. El
promedio individual del tiempo de llamadas fue significativamente ma´s ra´pido en G. cobanense (3.4 notas/
seg 60.5, n549 series de notas de seis individuos) que en G. gnoma (1.9 notas/seg 60.3, n534 series de
notas de ocho individuos). Esta nueva evidencia de diferencias vocales apoya la separacio´n taxono´ mica de
ambos taxones.
[Traduccio´n del equipo editorial]
The taxonomy of pygmy-owls of the Glaucidium
gnoma complex is vexed (Holt and Petersen 2000).
The American Ornithologists’ Union (1998 and
supplements) and Dickinson (2003) recognized on-
ly one species, Glaucidium gnoma, the Northern Pyg-
my-Owl, ranging from northwestern North America
through northern Central America. Modern treat-
ments, however, such as Marks et al. (1999) and
Ko¨nig and Weick (2008) recognized four species:
Northern (G. californicum), Mountain (G. gnoma),
Cape (G. hoskinsii) and Guatemalan (G. cobanense)
pygmy-owls. We follow the treatment of Marks et al.
(1999) and Ko¨nig and Weick (2008), and our data
provide further support for the species status of G.
cobanense. The Guatemalan Pygmy-Owl occurs in the
highlands of northern Central America southeast of
the Isthmus of Tehuantepec, including in Chiapas
(Mexico), Guatemala, and Honduras, and is geo-
1
Email address: knut.eisermann@proeval-raxmu.org
J. Raptor Res. 45(4):304–314
E2011 The Raptor Research Foundation, Inc.
304
graphically isolated from Mountain Pygmy-Owl,
which occurs in the highlands northwest of the isth-
mus of Tehuantepec, in Mexico (Howell and Webb
1995, Ko¨nig and Weick 2008). Sharpe (1875a,
1875b) classified the Guatemalan Pygmy-Owl based
on the plumage coloration of rufous-morph individ-
uals. Because coloration is variable in pygmy-owls,
Sharpe’s classification has often not been accepted
(Salvin and Godman 1897–1904, American Orni-
thologists’ Union 1998). Marks et al. (1999) treated
the Guatemalan Pygmy-Owl as a species, but indicat-
ed that this status may not be warranted. Ko¨nig and
Weick (2008) recognized it as a species because of
vocal differences, but omitted a detailed description
of its vocalization.
More recently, classifications of Glaucidium species
based on differences in vocalizations (Ko¨nig 1994,
Howell and Robbins 1995, Robbins and Howell
1995, Robbins and Stiles 1999) have been supported
by DNA-sequence data (Heidrich et al. 1995, Wink et
al. 2008). Here we describe vocalizations of Guatema-
lan Pygmy-Owls from the highlands of Guatemala
and Chiapas, Mexico, and compare them to vocaliza-
tions of Mountain Pygmy-Owls from Mexico.
STUDY AREA AND METHODS
The Guatemalan Pygmy-Owl occurs above 1500 m
in the highlands of Chiapas, Guatemala, and Hon-
duras. Natural vegetation in these mountains are
pine (Pinus spp.), oak (Quercus spp.), and pine-
oak forests in less-humid sections, cloud forests in
most-humid areas, and coniferous forests of cypress
(Neocupressus lusitanica) and fir (Abies guatemalensis)
in the highest areas above 2500 m. Natural vegeta-
tion in the owl’s range is fragmented by agricultural
crops (corn, coffee, pasture land; Ochoa-Ganoa and
Gonza´ lez-Espinosa 2000, Cayuela et al. 2006, Eiser-
mann and Avendan˜o 2006, Eitniear and Eisermann
2009, Eisermann et al. 2011).
We describe vocalizations of Guatemalan Pygmy-
Owl based on recordings of 11 individuals during
occasional observations at seven sites in the Atlantic
and Pacific slope highlands of Guatemala and Chia-
pas, Mexico (Table 1). KE recorded vocalizations in
Guatemala with a Fostex FR-2LE (enhanced by
Oade Brothers Audio) digital recorder and Senn-
heiser M67 directional microphone with a sample
rate of 96 kHz. SNGH recorded vocalizations in
Mexico with an Olympus LS-10 digital recorder
and a Sennheiser M66 directional microphone with
a sampling rate of 44.1 kHz. Vocalizations were an-
alyzed and sonograms produced with software Ra-
ven Pro 1.3 (Cornell Laboratory of Ornithology
2008). Contributing researchers used different re-
cording equipment (Marantz PMD661, Marantz
PMD-222, Uher 4000 L, Sony TCM-5000EV, Sony
Table 1. Sample sites for recordings of Guatemalan Pygmy-Owls.
SITE,DATE,AND RESEARCHER
GEOGRAPHIC
COORDINATES
COUNTRY,STATE/
PROVINCE
ELEVATION
(m) HABITAT
Reserva Chelemha´, Yalijux mountain
(January–April 2010, KE)
15u239N, 90u049W Guatemala, Alta Verapaz 2100 cloud forest edge
Reserva K’antı´ Shul, Yalijux mountain
(10 April 2010, KE)
15u249N, 90u049W Guatemala, Alta Verapaz 2300 cloud forest
Sanimtaca´, Sacranix mountain
(13 February 2010, KE)
15u299N, 90u289W Guatemala, Alta Verapaz 1500 pine-oak forest
Finca El Recuerdo, Cerro El Amay
(16 October 2010, KE)
15u279N, 90u469W Guatemala, Quiche´ 1700 pine-oak forest
Finca San Sebastian, Acatenango
volcano (4 January 2011, KE)
14u319N, 90u509W Guatemala,
Sacatepe´quez
1900 coffee plantation
with old growth oak
(Quercus sp.) shade
Finca Chilax, Xucaneb mountain
(24 November 2010, J.P. Cahill)
15u239N, 90u219W Guatemala, Alta Verapaz 1600 cloud forest edge
San Cristobal de las Casas, Chiapas
(3 March 2007, SNGH)
16u419N, 92u329W Mexico, Chiapas 2400 pine-oak forest
34 km SE of San Cristobal de las Casas,
Chiapas (13 March 2010, SNGH)
16u369N, 92u229W Mexico, Chiapas 2400 pine-oak forest
14 km SE of San Cristobal de las Casas,
Chiapas (15 March 2009, N. Athanas,
XC31724)
16u399N, 92u329W Mexico, Chiapas 2400 pine forest
DECEMBER 2011 GUATEMALAN PYGMY-OWL VOCALIZATIONS 305
TC-D5 Pro II). Voucher recordings were archived at
the Macaulay Library (Cornell Lab of Ornithology,
Ithaca, New York, U.S.A.; http://macaulaylibrary.
org). Voucher photographs were archived at VIREO
(Academy of Natural Sciences, Philadelphia, Penn-
sylvania, U.S.A.; http://vireo.acnatsci.org).
To compare call rate (notes/sec), length (sec),
and frequency (kHz) of notes between Guatemalan
Pygmy-Owls and Mountain Pygmy-Owls, recordings
of eight individuals from Mexico were analyzed.
SNGH recorded a bird at Cerro San Felipe, Oaxaca
(17u119N, 96u389W) on 19 March 2010. The other
recordings of Mountain Pygmy-Owl used for our
analysis were previously archived at the Macaulay
Library (ML) or at xeno-canto (xeno-canto.org,
XC): ML17195 (Sinaloa, 13 March 1976, T.A. Parker
III), ML53150 (Sinaloa, 30 March 1991, L.R. Macau-
lay), ML57735 (Jalisco, 13 March 1985, D. Delaney),
ML57736 (Jalisco, 13 March 1985, D. Delaney),
ML57737 (Jalisco, 13 March 1985, D. Delaney),
ML136513 (Sinaloa, 29 December 2001, M.J. Ander-
sen), XC9671-74 (La Cumbre, Oaxaca , 27 February
1995, A. Chartier). Locations where recordings were
obtained were plotted (Fig. 1).
For analyses, we marked onset and offset of sig-
nals in the sonograms using the curser in Raven Pro
1.3. Depending on the recording distance, one or
several harmonic frequencies were recorded, but
the fundamental frequency was always the dominant
one, and was used for all analyses. To lower bias of
signal onset and offset caused by manual signal se-
lection, we used the following robust signal mea-
surements determined with Raven Pro 1.3 for statis-
tical tests of significant differences (Charif et al.
2008): center frequency, center time, and Inter
Quartile Range (IQR) duration of notes. In addi-
tion, we measured peak frequency per note, which
is the frequency with the maximum power [dB]).
Figure 1. Localities of voice recordings of Guatemalan (Glaucidium cobanense) and Mountain Pygmy-Owls (G. gnoma)
and geographic ranges of both species. Recording sites: 1—Finca El Recuerdo, Quiche´, 2—Sanimtaca´ , Alta Verapaz, 3—
Finca Chilax, Alta Verapaz, 4—Chelemha´ Reserve, Alta Verapaz, 5—Finca San Sebastian, Sacatepe´ quez, 6–8—San Cris-
tobal de las Casas, Chiapas, Mexico, 9–10—La Cumbre, Oaxaca, Mexico, 11–13—Volca´n de Fuego, Jalisco, Mexico, 14—
Barranca Rancho Liebre, Sinaloa, Mexico, 15—El Palmito, Sinaloa, Mexico, 16—Durango highway, Sinaloa, Mexico.
CH—Chiapas, Mexico, GT—Guatemala, HN—Honduras, JA—Jalisco, Mexico, OA—Oaxaca, Mexico, SI—Sinaloa, Mex-
ico, SV—El Salvador.
306 EISERMANN AND HOWELL VOL. 45, NO.4
We determined mean individual center frequency
(Hz) and IQR duration (sec) of notes for each bird
using each note as a replicate unit. Mean individual
call rate (notes/sec) was determined by using each
call series as a replicate unit. Call series were de-
fined by pauses longer than intervals between calls.
For the calculation of call rate, only call series with
.3 calls were assessed. The time lapse of a call series
was limited by the center time of the first and the
last note.
Figure 2. Sonograms of territorial toot call of Guatemalan Pygmy-Owl (Glaucidium cobanense): (a) Toot call of a brown
morph male singing in the nest territory at 60 m from the nest (recording ML #161746, 12 March 2010, K. Eisermann);
(b) Single toot note of the same recording. Axes represent time and frequency according to the voice recording archived
at the Macaulay Library.
Table 2. Different parameters of territorial toot calls of Guatemalan Pygmy-Owl (Glaucidium cobanense) and Mountain
Pygmy-Owl (G. gnoma).
SPECIES
MEAN CALL RATE IN
NOTES/SEC (6SD)
MEAN LENGTH
(SEC)OF EACH
NOTE (6SD)
MEAN INTER QUARTILE
RANGE DURATION
(SEC)OF EACH
NOTE (6SD)
MEAN PEAK
FREQUENCY (HZ)OF
EACH NOTE (6SD)
MEAN CENTER
FREQUENCY (HZ)OF
EACH NOTE (6SD)
G. cobanense
a
3.4 60.5 0.11 60.02 0.032 60.009 1098.1 629.0 1094.6 628.6
n549 call series n52570 notes n52570 notes n52570 notes n52570 notes
G. cobanense
b,c
4.2 60.6 0.10 60.01 0.025 60.008 1126.2 637.6 1118.9 636.6
n5114 call series n51149 notes n51149 notes n51149 notes n51149 notes
G. gnoma
d
1.9 60.3 0.12 60.02 0.030 60.009 1096.8 656.6 1093.7 657.9
n534 call series n51399 notes n51399 notes n51399 notes n51399 notes
a
n56 individuals.
b
n55 individuals.
c
Vocalization elicited by playback, or unknown whether elicited by playback or spontaneous.
d
n58 individuals.
DECEMBER 2011 GUATEMALAN PYGMY-OWL VOCALIZATIONS 307
Figure 3. Sonograms of (a) rapid whiwhiwhi call of female Guatemalan Pygmy-Owl and (b) female duetting with male
(fundamental marked with brackets) emitting soft toot call. Axes represent time and frequency according to voice-
recording archived at the Macaulay Library (ML #161747, 12 March 2010, K. Eisermann).
308 EISERMANN AND HOWELL VOL. 45, NO.4
To assess relationships between Guatemalan and
Mountain Pygmy-Owls we used an unweighted pair-
group average (UPGMA) cluster analysis of vocali-
zations based on the Euclidean distance of call rate
(mean numbers of notes/sec) using PAST 2.08 soft-
ware (Hammer et al. 2001). Because call rate can
differ between spontaneously calling owls and those
responding to playback, we used only recordings of
spontaneous territorial toot calls of Mountain Pygmy-
Owls and Guatemalan Pygmy-Owls for comparative
analyses.
To compare vocal parameters between both spe-
cies, we first calculated individual means of the
length of each note, IQR duration, and center fre-
quency of each note. Means are reported 61 stan-
dard deviation (SD). A permutation test for equality
of means with a50.05 using PAST 2.08 software
(Hammer et al. 2001) was used to compare individ-
ual means between both species. This is a nonpara-
metric test, where observations are randomly moved
among the groups, and compared with the tstatistic
(the number of permutations is given with the test
results). We used this test because data were not
normally distributed, and the assumption of n.3
in each sample (Hammer 2011) was met.
RESULTS
We recorded four vocalization types of adult Gua-
temalan Pygmy-Owls. In addition to territorial toot
calls, three different vocalizations of a breeding pair
near the nest were documented.
Territorial Toot Calls. Among eleven individuals,
series of toot notes consisted of 1–300 notes, which
were spaced evenly or in pairs (Fig. 2). A bird in a
breeding pair could be identified as male; the sex of
the other birds remained unknown. The mean call
rate was higher in vocalizations elicited by broadcast
of conspecific calls (4.2 60.6 notes/sec, range 3.2–
6.8, n5114 call series of four individuals; Table 2),
than in vocalization not elicited by playback (3.4 6
0.5 notes/sec, range 2.8–5.4, n549 call series of 6
individuals) (permutation t-test, differences in
means 0.801, P,0.001, based on 1000 permuta-
tions). Mean individual length of each note among
six spontaneously vocalizing birds ranged between
0.08 and 0.13 sec and the mean length of each note
across all individuals was 0.11 60.02 sec; the mean
individual IQR duration ranged from 0.026 to
0.034 sec, and mean across all six individuals was
0.033 60.009 sec (Table 2). The mean individual
peak frequency of toot notes among six spontaneous-
ly vocalizing individuals ranged 1077.4–1112.9 Hz
(Table 2) and mean across all individuals was
1098.1 629.0 Hz.
Vocalizations Near the Nest. One breeding pair
of Guatemalan Pygmy-Owls was observed in the
Chelemha´ Reserve from 12 March to 17 April
2010. The owls occupied a human-made nest cavity
dug into a piece of a trunk of Brunellia mexicana
(Brunelliaceae), which was hung on a tree. The fe-
male was of the rufous morph and the male of the
brown morph (plate 14 in Marks et al. 1999), and
Table 3. Vocalizations other than territorial toot call of a breeding pair of Guatemalan Pygmy-Owls (voucher recording
ML #161747) (n51 individual for each vocalization type).
VOCALIZATION
TYPE
RANGE OF
NUMBER OF
NOTES/SERIES
MEAN CALL
RATE
(NOTES/SEC
6SD)
MEAN LENGTH
(SEC)OF EACH
NOTE (6SD)
MEAN INTER
QUARTILE RANGE
DURATION (SEC)OF
EACH NOTE (6SD)
MEAN PEAK
FREQUENCY
(HZ)OF EACH
NOTE (6SD)
MEAN CENTER
FREQUENCY
(HZ)OF EACH
NOTE (6SD)
Whiwhiwhi -call of
female
a
10–44 11.0 60.3 0.05 60.00 0.013 60.003 1551.9 647.3 1525.5 646.1
Krikrikri-call of
female during
copulation
b
2–3 36.5 62.4 0.03 60.01 0.008 60.003 1438.1 674.8 1443.7 668.3
Soft toot call of
male (fast part)
c
4–7 12.0 60.5 0.07 60.01 0.018 60.006 1020.4 624.6 1009.1 624.4
Soft toot call of
male (slow part)
d
4–7 4.9 60.4 0.09 60.01 0.023 60.005 1044.8 626.5 1041.1 627.0
a
n526 call series (in mean call rate column) and 419 notes.
b
n517 call series (in mean call rate column) and 50 notes.
c
n526 call series (in mean call rate column) and 186 notes.
d
n57 call series (in mean call rate column) and 38 notes.
DECEMBER 2011 GUATEMALAN PYGMY-OWL VOCALIZATIONS 309
the pair was observed copulating. Photographs of
both individuals are archived at VIREO (male: VIR-
EO #v06/60/004, 13 March 2010, C. Avendan˜o;
female: VIREO #v06/60/003, 12 March 2010, K.
Eisermann; pair: VIREO #v06/60/002, 12 March
2010, K. Eisermann). When the pair was establish-
ing occupation in the nest cavity, the male uttered
the toot call at a distance of 60 m from the nest. The
female near the nest often responded with a fast
series of short notes (11.0 60.3 notes/sec, n526
series), which can be described as a continued series
whiwhiwhi. Each series consisted of 10–44 notes with
a mean peak frequency of 1551.9 647.3 Hz (n5
419 notes). Up to seven harmonics were recorded
from 2600 Hz to 13 900 Hz (Fig. 3a, recording ML
#161747, 12 March 2010, K. Eisermann).
Near the nest, the male uttered soft toot notes that
were faster and lower-pitched than the territorial
toot notes. Toots were grouped into 2–7 notes (12.0
60.5 notes/sec, n526 groups), slowing down at
Figure 4. Sonogram of vocalization of a pair of Guatemalan Pygmy-Owls during copulation. Fundamentals of the male
soft toot calls are marked with a bracket, fundamentals of female notes are marked with a bracket (F) and female chirping
krikrikri notes with bracket (Fc). Chip notes of a mobbing Magnificent Hummingbird (Eugenes fulgens) are marked with 1.
Axes represent time and frequency according to voice recording archived at the Macaulay Library recording (ML
#161747, 12 March 2010, K. Eisermann).
310 EISERMANN AND HOWELL VOL. 45, NO.4
the end into 2–7 notes with a rate of 4.9 60.4
notes/sec, n57 groups; Fig. 3b). The mean peak
frequency of the fast sections was 1020.4 624.6 Hz
(n5186 notes), and of the slow sections was 1044.8
626.5 Hz (n538 notes). A harmonic was recorded
at about 2050 Hz. During the first days of nest oc-
cupation the soft toot call was uttered in duet with
the female whiwhiwhi call series (Fig. 3b, recording
ML #161747, 12 March 2010, K. Eisermann). Duet-
ting also preceded copulation. During copulation
the male uttered the soft toot series, and the female
uttered a vocalization composed of a fast series of
36.5 62.4 notes/sec (n517 series), grouped into
2–3 notes with a mean peak frequency of 1438 6
75 Hz (n550 notes), and chirping notes ranging in
frequency from 2730 to 7705 Hz (peak frequency
5766 Hz), sounding like krikrikri (Table 3; Fig. 4,
recording ML #161747, 12 March 2010, K. Eiser-
mann).
Comparison of Guatemalan Pygmy-Owl and
Mountain Pygmy-Owl Toot Calls. A classification of
six spontaneously calling Guatemalan Pygmy-Owls
and eight Mountain Pygmy-Owls based on an un-
weighted pair-group average (UPGMA) cluster anal-
ysis using Euclidean distance of mean call rate re-
sulted in two main clusters supporting the
taxonomic differentiation (Fig. 5). The mean call
rate in spontaneous vocalizations in Guatemalan
Pygmy-Owls was 3.4 60.5 notes/sec (n549 call
series of 6 individuals), significantly higher than in
Mountain Pygmy-Owls (1.9 60.3 notes/sec, n534
call series of 8 individuals; permutation t-test: differ-
ences in means 1.431, P,0.001, based on 1000
permutation; Table 2, Fig. 6). The mean length of
each note was similar in Mountain Pygmy-Owl (0.12
60.02 sec) and Guatemalan Pygmy-Owls (0.11 6
0.02 sec; permutation t-test comparing individual
means of IQR duration: differences in means
0.0004, P50.9, based on 1000 permutations).
Mean individual center frequency of each note
was similar in Guatemalan Pygmy-Owls (1094.6 6
28.6 Hz) and in Mountain Pygmy-Owls (1093.7 6
57.9 Hz; permutation t-test comparing individual
means: differences in means 15.5, P50.7, based
on 1000 permutations).
DISCUSSION
Differences in vocalizations are useful to distin-
guish owl species (Ko¨ nig 1994, Howell and Robbins
1995), but variability among individuals can be con-
siderable (Galeotti et al. 1993, Otter 1996, Delport
et al. 2002, Grava et al. 2008) and thus only certain
vocal parameters are useful for specific separation.
The frequency of notes in Glaucidium can be highly
variable among different individuals (Galeotti et al.
1993), but call rate (tempo) was suggested as an
important means to distinguish among Glaucidium
species (Howell and Robbins 1995). We found that
Figure 5. Unweighted pair-group average (UPGMA) cluster analysis of call rates (notes/sec) of toot calls of Mountain
Pygmy-Owls and Guatemalan Pygmy-Owls from different Mexican states and Guatemalan provinces.
DECEMBER 2011 GUATEMALAN PYGMY-OWL VOCALIZATIONS 311
toot calls of Guatemalan Pygmy-Owls differed from
those of Mountain Pygmy-Owls. Call rate was signif-
icantly faster in Guatemalan Pygmy-Owls, and a clus-
ter analysis based on call rate grouped samples in
two distant geographic clusters that differentiated
Guatemalan from Mountain Pygmy-Owls. This new
evidence of vocal differences supports full-species
treatment of the taxon restricted to the highlands
of northern Central America: Guatemalan Pygmy-
Owl (Glaucidium cobanense Sharpe 1875), as previ-
ously proposed (Howell and Webb 1995, Marks et
al. 1999, and Ko¨nig and Weick 2008).
The Guatemalan Pygmy-Owl is resident in the
highlands of Chiapas, Guatemala, and Honduras.
The species also occurs in the volcanic highlands
of southern Guatemala, which suggests that it may
also occur in the similar volcanic highland of west-
ern El Salvador, where it has not yet been docu-
mented (Komar 1998). Both Mountain Pygmy-Owl
and Guatemalan Pygmy-Owl are highland species
that occur at elevations .1500 m (Howell and Webb
1995), and their geographic ranges are separated by
approximately 200 km in the lowlands of the isth-
mus of Tehuantepec. In other Glaucidium species,
classification based on vocal differences has been
confirmed by molecular analyses (Howell and Rob-
bins 1995, Robbins and Howell 1995, Robbins and
Stiles 1999, Wink et al. 2008), which have not been
done for populations from the northern Central
American highlands. Further analyses should also
Figure 6. Sonograms of typical toot calls of (a) Guatemalan Pygmy-Owl (ML #161746, 12 March 2010, K. Eisermann),
(b) Mountain Pygmy-Owl from Sinaloa (ML #17195, 13 March 1976, T.A. Parker III), and (c) Mountain Pygmy-Owl from
Oaxaca (XC #9672, 27 February 1995, A. Chartier) to the same time scale.
312 EISERMANN AND HOWELL VOL. 45, NO.4
include the Costa Rican Pygmy-Owl (Glaucidium cost-
aricanum), whose range is separated from Guatema-
lan Pygmy-Owl by approximately 500 km. The for-
mer species also gives fast-paced toot calls, which are
somewhat similar in pace to those of Guatemalan
Pygmy-Owl (Stiles and Robbins 1999, Howell and
Eisermann 2011).
ACKNOWLEDGMENTS
We appreciate the assistance of Jessie Barry, Matthew A.
Young, and Tammy Bishop of the Macaulay Library (Cor-
nell Laboratory of Ornithology) for archiving of sound
recordings and for providing recordings from Mexico.
Recordists contributing to the Macaulay Library facilitated
the comparison with birds from Mexico. We thank Nick
Athanas for his contribution of a recording from Chiapas,
Allen Chartier for contributing recordings from Oaxaca,
and John Paul Cahill for a recording from Alta Verapaz.
Claudia Avendan˜ o provided a photograph. We thank
Paula Enrı´quez for information on the distribution of
pygmy-owls in Chiapas, and Daniel Thomas for his assis-
tance in archiving photographs at VIREO (Academy of
Natural Sciences). KE appreciates hospitality and logisti-
cal support by Francisco Falla during observations at
Finca San Sebastian, Julio Garcı´a at Finca El Recuerdo,
and the hospitality and research permission in the Che-
lemha´ and K’antı´ Shul private nature reserves provided by
UPROBON and FUNDASELVA, and Claudia Avendan˜o
for field assistance. SNGH thanks Will Russell and WINGS
for supporting travels in Mexico, Chris Wood and Rich
Hoyer for company in the field, and Nathan Pieplow for
help with digitizing recordings. The manuscript was im-
proved through critical reviews by Loı
¨c Hardouin, Joseph
Buchanan, and two anonymous reviewers, and through a
review of English usage by Christina Riehl of the Associ-
ation of Field Ornithologists’ program of editorial assis-
tance. We appreciate statistical advice by Carlos Aven-
dan˜ o. This is a contribution of the PROEVAL RAXMU
Bird Monitoring Program, which is supported by U.S.
Fish and Wildlife Service, Stiftung Artenschutz (Ger-
many), Heifer International Guatemala, Verein Sa¨ch-
sischer Ornithologen (Germany), and Cayaya Birding
(Guatemala).
LITERATURE CITED
AMERICAN ORNITHOLOGI STS’UNION. 1998. The American
Ornithologists’ Union check-list of North-American
birds, Seventh Ed. American Ornithologists’ Union,
Washington, DC U.S.A.
CAYUELA, L., J.M. REY BERNAYAS,AND C. ECHEVERRI
´A. 2006.
Clearance and fragmentation of tropical montane for-
ests in the highlands of Chiapas, Mexico (1975–2000).
Forest Ecology and Management 226:208–218.
CHARIF, R.A., A.M. WAACK,AND L.M. STRICKMAN. 2008. Ra-
ven Pro 1.3 user’s manual. Cornell Laboratory of Orni-
thology, Ithaca, NY U.S.A.
CORNELL LABORATORY OF ORNITHOLOGY. 2008. Raven Pro
1.3. http://www.birds.cornell.edu/raven (accessed 29
June 2010).
DELPORT, W., A.C. KEMP,AND J.W.H. FERGUSON. 2002. Vocal
identification of individual African Wood Owls Strix
woodfordii: a technique to monitor long-term adult turn-
over and residency. Ibis 144:30–39.
DICKINSON, E.C. 2003. The Howard and Moore complete
checklist of the birds of the world, Third Ed. Princeton
Univ. Press, Princeton, NJ U.S.A.
EISERMANN,K.AND C. AVENDAN
˜O. 2006. Diversidad de aves
en Guatemala, con una lista bibliogra´fica. Pages
525–623 in E. Cano [ED.], Biodiversidad de Guate-
mala, Vol. 1. Universidad del Valle de Guatemala, Gua-
temala.
———, S. ARBEITER,G.LO
´PEZ,C.AVENDAN
˜O,AND J.D. LEO
´N
LUX. 2011. Distribution, habitat use, and implications for
the conservation of the globally threatened Azure-rumped
Tanager Tangara cabanisi in Guatemala. Bird Conservation
International 21: doi:10.1017/S0959270910000638.
EITNIEAR, J.C. AND K. EISERMANN. 2009. Status and recent
sightings of Ocellated Quail. International Journal of Gal-
liformes Conservation 1:85–93.
GALEOTTI, P., M. PALADIN,AND G. PAVAN. 1993. Individually
distinct hooting in male pygmy-owls Glaucidium passer-
inum: a multivariate approach. Ornis Scandinavica
24:15–20.
GRAVA, T., N. MATHEVON,E.PLACE,AND P. BALLUET. 2008.
Individual acoustic monitoring of the European Eagle
Owl Bubo bubo.Ibis 150:279–287.
HAMMER, Ø. 2011. PAST paleontological statistics, version
2.08, reference manual. Natural History Museum, Uni-
versity of Oslo, Oslo, Norway, http://folk.uio.no/
ohammer/past (last accessed 5 April 2011).
———, D.A.T. HARPER,AND P.D. RYAN. 2001. PAST:
Paleontological Statistics software package for edu-
cation and data analysis. Paleontologia Electronica 4:
1–9.
HEIDRICH,P.,C.KO
¨NIG,AND M. WINK. 1995. Bio-
akustik, Taxonomie und molekulare Systematik amer-
ikanischer Sperlingska¨uze (Strigidae: Glaucidium
spp.). Stuttgarter Beitra¨ge fu¨r Naturkunde Serie A 534:1–
47.
HOLT,D.W.AND J.L. PETERSEN. 2000. Northern Pygmy-
Owl (Glaucidium gnoma). In A. Poole and F. Gill
[EDS.], The birds of North America, No. 494. The Aca-
demy of Natural Sciences, Philadelphia, PA and The
American Ornithologists’ Union, Washington, DC
U.S.A.
HOWELL, S.N.G. AND K. EISERMANN. 2011. Guatemalan Pyg-
my-Owl Glaucidium cobanense is a good species. Neotrop-
ical Birding 9:74–76.
——— AND M.B. ROBBINS. 1995. Species limits of the Least
Pygmy-Owl (Glaucidium minutissimum) complex. Wilson
Bulletin 107:7–25.
——— AND S. WEBB. 1995. A guide to the birds of Mexico
and northern Central America. Oxford Univ. Press,
New York, NY U.S.A.
KOMAR, O. 1998. Avian diversity in El Salvador. Wilson Bul-
letin 110:511–533.
DECEMBER 2011 GUATEMALAN PYGMY-OWL VOCALIZATIONS 313
KO
¨NIG, C. 1994. Biological patterns in owl taxonomy, with
emphasis on bioacoustical studies on Neotropical pyg-
my (Glaucidium) and screech owls (Otus). Pages 1–19 in
B.-U. Meyburg and R.D. Chancellor [EDS.], Raptor con-
servation today: proceedings of the IV World Confer-
ence on Birds of Prey and Owls. Pica Press/World
Working Group on Birds of Prey, Sussex, U.K.
——— AND F. WEICK. 2008. Owls of the world, Second Ed.
Christopher Helm, London, U.K.
MARKS, J.S., R.J. CANNINGS,AND H. MIKKOLA. 1999. Family
Strigidae: typical owls. Pages 76–242 in del Hoyo, J., A.
Elliott, and J. Sargatal [EDS.], Handbook of the birds of
the world, Vol. 5. Barn-owls to hummingbirds. Lynx
Edicions, Barcelona, Spain.
OCHOA-GANOA,S.AND M. GONZA
´LEZ-ESPINOSA. 2000. Land
use patterns and deforestation in the highlands of
Chiapas, Mexico. Applied Geography 20:17–42.
OTTER, K. 1996. Individual variation in the advertising call
of male Northern Saw-whet Owls. Journal of Field Orni-
thology 67:398–405.
ROBBINS, M.B. AND S.N.G. HOWELL. 1995. A new species of
pygmy-owl (Strigidae: Glaucidium) from the eastern An-
des. Wilson Bulletin 107:1–6.
——— AND F.G. STILES. 1999. A new species of pygmy-owl
(Strigidae: Glaucidium) from the Pacific slope of the
northern Andes. Auk 116:305–315.
SALVIN,O.AND F.D. GODMAN. 1897–1904. Biologia Centrali-
Americana. Aves. Vol. 3. Taylor and Francis, London,
U.K.
SHARPE, R.B. 1875a. Contributions to a history of the Accip-
itres. Notes on birds of prey in the museum at the
Jardin des Plantes and in the collection of Mons. A.
Bouvier. Ibis 5(Ser. 3):253–261.
———. 1875b. Catalogue of birds in the British Museum,
Vol. 2 Striges. Trustees of the British Museum (Natural
History), London, U.K.
WINK, M., P. HEIDRICH,H.SAUER-GU
¨RTH, A.-A. ELSAYED,J.
GONZALEZ. 2008. Molecular phylogeny and systematics
of owls (Strigiformes). Pages 42–63 in C. Ko¨ nig and F.
Weick [EDS.], Owls of the world, Second Ed. Christo-
pher Helm, London, U.K.
Received 13 August 2010; accepted 14 July 2011
Associate Editor: Joseph B. Buchanan
314 EISERMANN AND HOWELL VOL. 45, NO.4
... Similar changes have occurred in the genus Glaucidium Robbins and Stiles 1999). Our current knowledge of both genera is based on taxonomic revisions in the last 70 years (Moore and Peters 1939;Buchanan 1964;Howell and Robbins 1995;Wink et al. 2008;Eisermann and Howell 2011). Molecular studies have increased the number of owl species, but the number of accepted species differs considerably between authors (Table 2.1). ...
... Other authors have classified all or some of the four taxa as subspecies of G. gnoma (Weick 2006;Dickinson and Remsen 2013;Clements et al. 2016). A recent comparative study on vocalizations of G. cobanense and G. gnoma (Eisermann and Howell 2011;Howell and Eisermann 2011) found differences supporting the species status of G. cobanense, as originally proposed (Sharpe 1875;Griscom 1931). Molecular studies are required in order to confirm the new taxonomic status of pygmy owls in northern Central America (Heidrich et al. 1995). ...
... Other authors have classified all or some of the four taxa as subspecies of G. gnoma (Weick 2006;Dickinson and Remsen 2013;Clements et al. 2016). A recent comparative study on vocalizations of G. cobanense and G. gnoma (Eisermann and Howell 2011;Howell and Eisermann 2011) found differences supporting the species status of G. cobanense, as originally proposed (Sharpe 1875;Griscom 1931). Molecular studies are required in order to confirm the new taxonomic status of pygmy owls in northern Central America (Heidrich et al. 1995). ...
Article
Full-text available
Dietary studies are one of the most developed research areas in biology and ecology studies of Neotropical owls, but most of these studies have focused on few species. Our study describes the diet of Barn Owl (Tyto alba), Spectacled Owl (Pulsatrix perspicillata), and Rufous-banded Owl (Strix albitarsis) in Jardin and Ciudad Bolivar, western Andes of Colombia. The diet of T. alba, based on 495 prey items consisted 98.6% of vertebrates, the main food items being rodents (66%) and shrews (21.4%). Out of 142 prey items identified from P. perspicillata fractured pellets, the main prey species were Artibeus lituratus (23.9%), Rattus norvegicus (21.8%), and Didelphis sp. (16.1%), species of small and medium-sized mammals that tolerate environmental changes and often live in urban areas. Pulsatrix per-spicillata preyed also on at least 14 bird species including hummingbirds and migratory birds. Based on 165 prey items S. albitarsis consumed more invertebrates (57.7%) than vertebrates (42.3%). Among the insects, the main preys were Coleoptera beetles and Orthoptera crickets. Among the vertebrates, the main prey species included mammals such as Thomasomys aureus, Marmosops sp., Marmosa sp., and Reithrodontomys mexicanus. These scansorial species are likely to be vulnerable to aerial predators such as S. albitarsis which hunt from a perchs. According to standardized Levins index values T. alba was the most selective in its food habits, P. perspicillata had intermediate values, while S. albitarsis showed the least selective diet. RESUMEN · Dieta de la Lechuza Común (Tyto alba), el Búho de Anteojos (Pulsatrix perspicillata) y el Búho Ocelado (Strix albitarsis) en la cordillera Occidental de Colombia Los estudios sobre hábitos tróficos constituyen la línea de investigación más desarrollada dentro de la biología y ecología de los búhos Neotropicales, pero la mayoría de esos estudios se han centrado en pocas especies. El propósito de este estudio es describir la dieta de la Lechuza Común (Tyto alba), el Búho de Anteojos (Pulsatrix perspicillata) y el Búho Ocelado (Strix albitarsis), en Jardín y Ciudad Bolívar, cordillera Occidental de Colombia. Identificamos 495 presas consumidas por T. alba. Su dieta estuvo compuesta en un 98.7% de vertebrados, principalmente roedores (66%) y musarañas (21.4%). De 142 presas de P. perspicillata, las pre-sas principales, Artibeus lituratus (23.9%), Rattus norvegicus (21.8%) y Didelphis sp. (16.1%), son especies tolerantes a los ambientes intervenidos y hacen parte de los ensamblajes de pequeños mamíferos encontrados en ambientes urbanos. Pulsatrix perspicillata consumió también al menos 14 especies de aves incluyendo colibríes y aves migrato-rias. En base a 165 presas S. albitarsis consumió más invertebrados (57.7%) que vertebrados (42.3%). Entre los insec-tos depredó en mayor porcentaje los ordenes Coleoptera y Orthoptera, mientras que entre los vertebrados predominaron los de hábitos escansoriales (Thomasomys aureus, Marmosops sp., Marmosa sp. y Reithrodontomys mexicanus). Estos vertebrados serían más vulnerables a depredadores aéreos como S. albitarsis, la cual caza desde perchas en árboles. De acuerdo a los valores obtenidos para el indice estandarizado de Levins, T. alba fue más selec-tiva en el consumo de las presas, seguida por P. perspicillata, mientras que S. albitarsis tiene la dieta menos selectiva.
... Alta Verapaz (Sharpe 1875b;Dickerman 1987). The recent descrip-tion of vocalizations (Eisermann and Howell 2011;Howell and Eisermann 2011) supports the specific separation of Guatemalan pygmy owl from mountain pygmy owl (Glaucidium gnoma) in the Mexican highlands northwest of the Isthmus of Tehuantepec. In Guatemala, Guatemalan pygmy owl is widespread in the highlands at 1500-3400 m (mainly above 1800 m) (Table 13. ...
... Alta Verapaz (Sharpe 1875b;Dickerman 1987). The recent descrip-tion of vocalizations (Eisermann and Howell 2011;Howell and Eisermann 2011) supports the specific separation of Guatemalan pygmy owl from mountain pygmy owl (Glaucidium gnoma) in the Mexican highlands northwest of the Isthmus of Tehuantepec. In Guatemala, Guatemalan pygmy owl is widespread in the highlands at 1500-3400 m (mainly above 1800 m) (Table 13. ...
... Gerhardt et al. (1994a, b), described breeding biology, home range, and food of Mexican wood owl and black-and-white owl in the Parque Nacional Tikal, and Gerhardt and Gerhardt (1997) published biometric data for both species. Eisermann and Howell (2011) described four different vocalizations of Guatemalan pygmy owl from the Guatemalan highlands, and Eisermann (2013) described vocalizations of unspotted saw-whet owl. Eisermann et al. (2017) described first nesting and habitat of flammulated owl in Guatemala. ...
Chapter
https://link.springer.com/chapter/10.1007/978-3-319-57108-9_13 This compilation of recent data on the distribution, ecology, and conservation status of owls (Strigiformes) in Guatemala is based on an extensive literature review and numerous unpublished observations. Twenty species of owls have been recorded in Guatemala, of which 18 are resident. Breeding has been reported for 17 species, and it is assumed for one species. Two species are considered rare or accidental nonbreeding visitors to Guatemala during the northern winter. Guatemala’s region with the highest species richness in owls is the highlands, where 17 species have been recorded. Twelve species have been recorded in the Pacific slope lowlands and 13 species in the Atlantic slope lowlands. We analyzed the data in the presence and relative abundance of owls from 105 sites from 1989 to 2016. According to the weighted mean value of the relative abundance index across three ornithogeographic regions, the most common owls in the country are (abundance ranking in descending order): Mexican wood owl (Strix squamulata), Ridgway’s pygmy owl (Glaucidium ridgwayi), Guatemalan screech owl (Megascops guatemalae), black-and-white owl (Strix nigrolineata), American barn owl (Tyto furcata), Central American pygmy owl (Glaucidium griseiceps), Guatemalan pygmy owl (Glaucidium cobanense), great horned owl (Bubo virginianus), fulvous owl (Strix fulvescens), unspotted saw-whet owl (Aegolius ridgwayi), whiskered screech owl (Megascops trichopsis), crested owl (Lophostrix cristata), and Pacific screech owl (Megascops cooperi). Guatemala has an adequate legal framework to protect owl species (32% of the country is legally protected), but the conservation is not efficient, causing threats to owl populations. Of 18 resident owl species, 12 are forest specialists. In a vulnerability assessment applying IUCN Red List criteria on a national level, one species has been evaluated as Critically Endangered (CR), one as Endangered (EN), nine as Vulnerable (VU), five as Near Threatened (NT), two as Least Concern (LC), and two as not applicable. Habitat alterations through agriculture, mining, and oil drilling are the main threats. Of the remaining forests, 14% (5500 km²) were lost from 2000 to 2010, and the pressure on natural habitat will further increase. In addition, owls in Guatemala are threatened by direct persecution because of popular superstitions. The network of 21 Important Bird Areas (IBA) in Guatemala includes populations of all owl species. Three species have been recorded in at least 10 IBAs, 12 species in 5–9 IBAs, 4 in 2–4 IBAs, and 1 species in only one IBA. We consider the increase of the education level among the Guatemalan society the main key to protect habitats within the IBAs. A higher level of education would help to slow down population growth, increase environmental awareness, and consequently diminish pressure on natural areas.
... Similar changes have occurred in the genus Glaucidium Robbins and Stiles 1999). Our current knowledge of both genera is based on taxonomic revisions in the last 70 years (Moore and Peters 1939;Buchanan 1964;Howell and Robbins 1995;Wink et al. 2008;Eisermann and Howell 2011). Molecular studies have increased the number of owl species, but the number of accepted species differs considerably between authors (Table 2.1). ...
... Other authors have classified all or some of the four taxa as subspecies of G. gnoma (Weick 2006;Dickinson and Remsen 2013;Clements et al. 2016). A recent comparative study on vocalizations of G. cobanense and G. gnoma (Eisermann and Howell 2011;Howell and Eisermann 2011) found differences supporting the species status of G. cobanense, as originally proposed (Sharpe 1875;Griscom 1931). Molecular studies are required in order to confirm the new taxonomic status of pygmy owls in northern Central America (Heidrich et al. 1995). ...
... Other authors have classified all or some of the four taxa as subspecies of G. gnoma (Weick 2006;Dickinson and Remsen 2013;Clements et al. 2016). A recent comparative study on vocalizations of G. cobanense and G. gnoma (Eisermann and Howell 2011;Howell and Eisermann 2011) found differences supporting the species status of G. cobanense, as originally proposed (Sharpe 1875;Griscom 1931). Molecular studies are required in order to confirm the new taxonomic status of pygmy owls in northern Central America (Heidrich et al. 1995). ...
Chapter
Full-text available
Although birds belong to the best known animal groups, their systematics has not been fully resolved yet. Among the approximately 80 Neotropical owl species, there are monotypic genera such as Lophostrix, complex and diverse genera such as Megascops or Glaucidium, as well as widespread and variable taxa such as Bubo virginianus and Tyto furcata. Based on a literature review, we provide here an overview of the current taxonomy and nomenclature of Neotropical owls, and indicate knowledge gaps as focus points for future research.
... NORTHERN PYGMY OWL Glaucidium gnoma (C; R) G. g. cobanense (Guatemalan Pygmy Owl), which occurs in Mexico south-east of the Isthmus of Tehuantepec and in northern Central America has distinctive vocalisations (Eisermann & Howell 2011) and may represent a separate species. G. g. cobanense is fairly common throughout the Guatemalan highlands at 1,800-3,400 m, rarely to 1,400 m. ...
Article
Full-text available
We present an update on the status and distribution of birds in Guatemala relative to a previous summary (Eisermann & Avendaño 2007) and based upon a review of new published and unpublished records. During the period 2006 to 2017, 50 species were first documented in Guatemala. Another 11 species were reported for the first time but without verifiable documentation. Breeding was newly confirmed for 58 species. Noteworthy observations, including range extensions, are summarised for 131 species. The Guatemalan avifauna now comprises 758 species of which 23 lack documentation. Of the 758 species, 509 breed in Guatemala, 240 are non-breeding visitors, transients or vagrants, and the status of nine is uncertain.
Article
Full-text available
Vocal individuality has been used as a monitoring tool, and two criteria are a prerequisite: high variation among individuals and low variation within individuals, and vocal consistency within and across seasons. We examined individual variation in the territorial hoot calls of the tawny owl (Strix aluco) to discriminate between males and to assess a possible conservation technique that would allow for monitoring individuals within a study area. The territorial calls were recorded from five males in the Naejang Mountain National Park in South Korea during the breeding season in 2015 and 2016 and analyzed both quantitatively and qualitatively to determine the amount of variation within and between individuals. Our results showed that the territorial calls were specific to individuals within a population and that the acoustic distances between males living in the same territory during the two years were the smallest for the four nesting sites. Our results suggest that territorial calls of the tawny owls are individually identifiable over two years and that this acoustic technique can be useful for monitoring individual site fidelity.
Article
Full-text available
Owls belong to the least studied Neotropical birds. In Mexico and Central America (Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama), 38 owl species have been recorded, of which six have a restricted distribution ,50,000 km2. Of the 38 species, 17 (45%) are restricted to Mexico y Central America. Biogeographic zones with the highest species richness are the lowlands of the Pacific slope (23 species) and the highlands of northern Mexico (21), followed by the highlands of northern Central America (15), the lowlands of the Gulf-Caribbean slope (15), and the highlands of southern Central America (12). A classification of the state of knowledge on the ecology of owls restricted to Mexico and Central America showed that no species has been studied in detail. Best known species are Bearded Screech-Owl Megascops barbarus and Guatemalan Screech-Owl M. guatemalae,and least known are Oaxaca Screech-Owl Megascops lambi, Cape Pygmy-Owl Glaucidium hoskinsii,Unspotted Saw-whet Owl Aegolius ridgwayi,and Fulvous Owl Strix fulvescens. Common and widespread species such as Pacific Screech-Owl Megascops cooperi,Whiskered Screech-Owl M. trichopsis,Ridgway’s Pygmy-Owl Glaucidium ridgwayi,and Central American Pygmy-Owl G. griseicepshave not been studied in detail in the region. Migration and local movements, home range, demography and population trends remain little known. Until 2011, none of the Mexican and Central American owl species were classified as threatened in the IUCN Red List of globally threatened species. On a national level, however, most of the species are considered as threatened. Habitat loss is the main threat for Mexican and Central American owls. Many species are associated with forest ecosystems, which are shrinking because of conversion to agricultural area. Protected areas cover 14% of terrestrial areas of Mexico and Central America (1%–37% of national areas). Many protected areas are in peril because of the expansion of agricultural areas, wood extraction and hunting. The recent identification of Important Bird Areas (IBAs) in the region (15%–66% of national areas) showed that protected areas are insufficient for conservation. To improve the conservation of Neotropical owls it is necessary to increase the knowledge about populations and communities, and involve all parts of the society in conservation priorities.
Article
Full-text available
Variation in a species' song could potentially be used in monitoring populations of secretive birds. I recorded advertising calls from five captive male Northern Saw-whet Owls (Aegolius acadicus) and used sonagraphic analysis to assess individuality in voice. All males were recorded several times on at least three different nights. The mean frequency of the sustained component of an individual's calls was highly distinctive; only two owls shared a similar mean call frequency. Internote interval and note length were not as individually distinctive; although these features varied significantly among males, there was as much or more variation among nights for the same male. I suggest that male Saw-whet Owls can be accurately identified using sonagraphic analysis of calls in combination with knowledge about the location of the singer.
Article
Full-text available
Recent field studies have revealed many species of birds new for El Salvador suggesting that the country's few protected areas may be especially important for conserving regional biodiversity. Seventeen percent of the landscape or 359,000 ha is covered with natural forest or scrub habitats, of which 38,000 ha are coastal mangrove forests. An additional 196,000 ha (9% of El Salvador) are coffee plantations, a forest-like habitat used by many birds. Of 508 bird species known to occur in the country, 310 are breeding residents; the others are migratory visitors, transients, or vagrants. Seventeen species occurring in El Salvador are endemic to the highlands of northern Central America and one species is endemic to the Pacific slope lowlands of northern Central America. About 270 species are habitat specialists with highly restricted ranges within El Salvador. In all, 254 species (>50% of the avifauna) are threatened by habitat loss, pollution, hunting, and exploitation for the pet trade. Of these, 117 are in danger of extinction at the national level and three are believed already extirpated. Much additional field work is needed to understand the status and abundance of El Salvador's birds. This report includes a complete list of reported species with classification of residency status, threatened status, and distribution. This list can serve as a resource for interpreting field observations produced by environmental impact studies or conservation projects in El Salvador. A second list includes 73 species that probably occur in El Salvador but have not been reported.
Article
Full-text available
We describe a new species of pygmy-owl that is restricted to very wet cloud forest at 1,400 to 2,000 m in elevation along the Pacific slope of the western Andes of Colombia and Ecuador. This taxon had been long overlooked as a result of its morphological similarity and geographic proximity to the Andean Pygmy-Owl (Glaucidium jardinii), but it is vocally very distinct and exhibits subtle but consistent morphological differences as well. Vocally, the new species is most similar to the Costa Rican-Panamanian form G. costaricanum and to the nominate subspecies of Northern Pygmy-Owl (G. gnoma), but again, consistent differences exist in vocalizations and morphology. Glaucidium costaricanum has long been considered a subspecies of G. jardinii, but at least one recent author treated it as a subspecies of G. gnoma. Genetic, vocal, ecological, and morphological data indicate that G. costaricanum should be elevated to species level, and it along with the new species are considered allospecies within the Northern Pygmy-Owl superspecies complex.
Data
Full-text available
Ocellated quail is a poorly known and little studied species, rarely observed in the wild. It occurs from south western Mexico through Guatemala, El Salvador, Honduras and north central Nicaragua. Montezuma and ocellated quail are biogeographically separated by the tropical lowlands of the Isthmus of Tehuantepec, in south western Mexico and are believed to be allopatric replacement forms. Collections for museums and observations in the wild have been sparse over the last 50 years. This paper reports recent observations and their proximity to protected areas.
Article
A new species of pygmy-owl (Glaucidium parkeri sp. nov.) from the eastern slope of the eastern Andes of Ecuador and Peru is described. This subcanopy dwelling species appears to be uncommon in subtropical forest on outlying ridges of the main Andean chain between 1450 and 1975 m elevation. Plumage and vocalizations indicate that it is allied to the Least Pygmy-Owl (G. minutissimum) complex. Received 8 Nov. 1993, accepted 8 May 1994. In 1969 and 1970, John Weske and John Terborgh mist-netted two pygmy-owls along the eastern slope of the Andes in central Peru (Deptos. Ayacucho and Huanuco) that were identified as Glaucidium minutissimum based on their small size. Nearly three years ago, during the initial stages of our revision of the Glaucidium minutissimum complex (Howell and Robbins 1995), we independently examined these specimens in the Amer-ican Museum of Natural History (AMNH 820933, 820647) and concluded that they represented an undescribed taxon. Aside from the data on the specimen labels, nothing was known about this taxon until Bret Whitney sent us a tape recording that he made on 21 January 1991 of a probable G. minutissimum at 1660 m on the lower slopes of Volcan Sumaco, Prov. Napo, Ecuador. When Robbins listened to Whitney' s tape, he realized that birds he had tape recorded between 1700 and 1975 m in the Cordillera de Cutucu (Library of Natural Sounds, Cornell Laboratory of Ornithol-ogy, #41504; Robbins et al. 1987), and originally identified as G. jurdinii, were referable to the same species as in the Whitney recording.