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39
ORNITOLOGIA NEOTROPICAL 22: 39–57, 2011
© The Neotropical Ornithological Society
NESTING ECOLOGY OF THE ENDANGERED AZURE-RUMPED
TANAGER (TANGARA CABANISI) IN GUATEMALA
Knut Eisermann1, Susanne Arbeiter1,2, Gerardo López3, Claudia Avendaño1, Josué de
León Lux3, Andy Burge3, Aaron de León Lux3, & Everilda Buchán3
1 PROEVAL RAXMU Bird Monitoring Program, Cobán, Alta Verapaz, Guatemala. c/o P.O.
Box 98 Periférico, Guatemala City, Guatemala. E-mail: knut.eisermann@proeval-raxmu.org
2 University of Applied Sciences Eberswalde, Friedrich-Ebert-Str. 28, 16225 Eberswalde,
Germany.
3 Los Tarrales Reserve, Km 164.2 Ruta Nacional 11, Patulul, Suchitepéquez, Guatemala.
Resumen. – Ecología de anidación de Tangara cabanisi en Guatemala. – La Tángara de Cabanis
(Tangara cabanisi) es una especie poca estudiada y en Peligro de Extinción, con un área de distribución
restringida a las tierras altas de la vertiente Pacífica de Guatemala y Chiapas, México. Estudiamos la
ecología de anidación de esta especie en la vertiente sur-este del volcán Atitlán, departamento de
Suchitepéquez, Guatemala. Un total de 32 nidos fue registrado en Guatemala en los años 2001–2009,
de los cuales 30 fueron observados en volcán Atitlán. La altitud de los lugares de anidamiento varió
entre 860 y 1850 m. Quince nidos fueron localizados en bosque latifoliado con una distancia hasta la
orilla del bosque más cercano variando entre 0–700 m. Otros 17 nidos se encontraron en plantaciones
de café y hábitat de huertas caseras con una distancia variable de 5–130 m hasta la orilla del bosque
más cercano. Registramos tángaras anidando exitosamente en bosque primario latifoliado, pero tam-
bién en plantaciones con dosel superior muy reducido o ausente de árboles latifoliados nativos. Los 32
nidos fueron ubicados en 20 especies diferentes de árboles. La anidación se observó en todos los
meses de abril a septiembre y estuvo sincronizada con la época lluviosa. Un nido proveyó datos desde
el primer día de construcción hasta cuando los juveniles salieron. La construcción del nido tardó seis
días, la incubación 14 días y la crianza de los pichones 17 días, lo cual es un tiempo más largo de cri-
anza de pichones en la Tángara de Cabanis que el reportado en Chiapas y otras especies del mismo
género en el neotrópico. Usando el método Mayfield para calcular la sobrevivencia de nidos desde el ini-
cio de incubación hasta la salida del primer pichón del nido, el éxito de anidación fue de 16% (intervalo
de confianza de 95%: 5–45%). Nuestros descubrimientos proveen una base para medidas prácticas de
conservación en el paisaje dominado por plantaciones de café en la vertiente Pacífica de las tierras altas
de Guatemala y Chiapas.
Abstract. – The Azure-rumped Tanager (Tangara cabanisi) is a little studied and endangered species
restricted to the Pacific slope mountains of Guatemala and Chiapas, Mexico. We studied the nesting
ecology of this species on the south-eastern slope of Atitlán volcano, dpto. Suchitepéquez, Guatemala,
and compiled information of other nesting sites. Thirty-two nests were recorded in Guatemala from
2001–2009, of which 30 were observed at Atitlán volcano. The altitude of nesting sites ranged from 860
to 1850 m. Fifteen nests were located in broadleaf forest with a distance to the nearest forest edge rang-
ing from 0–700 m. Another 17 nests were in coffee plantations and orchard-like habitat with a distance
from the nearest forest ranging from 5–130 m. We recorded tanagers nesting successfully in primary
broadleaf forest, but also in plantations with a greatly reduced or absent upper canopy of native broad-
leaf trees. The 32 nests were placed in 20 different tree species. Nesting was observed in all months
from April through September and was synchronized with the wet season. One nest provided data from
40
EISERMANN ET AL.
the first day of nest-building to the fledging of juveniles. Nest-building took six days, incubation 14 days,
and brooding 17 days, which is longer than the nestling period observed previously for the Azure-rumped
Tanager in Chiapas and for congeners throughout the Neotropics. Using the Mayfield method for calcu-
lating nest survival from onset of incubation to the fledging of the first young, nest success was 16%
(95% confidence interval: 5–45%). Our findings provide a base for practical conservation measures in
the coffee-dominated landscape of the Guatemalan and Chiapan Pacific slope highlands. Accepted 31
January 2011.
Key words: Azure-rumped Tanager, Tangara cabanisi, broadleaf forest, coffee plantation, cooperative
breeding, natural history, nest site selection, nest success.
INTRODUCTION
The Azure-rumped Tanager (Tangara cabanisi)
is restricted to the Pacific slope mountains of
Guatemala and Chiapas, Mexico, where it has
been reported in a narrow altitudinal belt at
860–1900 m (Parker III et al. 1976, Hilty &
Simon 1977, Heath & Long 1991, Eisermann
et al. 2011). The tanager is considered Endan-
gered at the global level because of its small
range size and loss of habitat, primarily
through the replacement of broadleaf forests
by coffee plantations (Collar et al. 1992,
BirdLife International 2008, Eisermann et al.
2011). Due to the limited distribution and few
observations, to date little has been published
on the ecology and behavior of the Azure-
rumped Tanager.
Available information on habitat use origi-
nates from observations in the Sierra Madre
de Chiapas (Brodkorb 1939, Heath & Long
1991) and from recent studies in Guatemala
(Cooper 2003, Eisermann et al. 2011). Exist-
ing information on nesting is limited to a few
nests which were observed in humid broad-
leaf forest in Chiapas in the early wet season
(April–June; Isler & Isler 1987, Long & Heath
1994). Gómez de Silva Garza (1997) observed
an additional nest in coniferous forest from
April to May. In Guatemala, only two nests
have previously been reported, from Atitlán
volcano and from Santa María de Jesús,
Quetzaltenango (Eisermann & Avendaño
2007).
Conservation planning for threatened
species requires information on their natural
history. Previously we described the current
distribution of Azure-rumped Tanager in
Guatemala, the extent of remaining prime
habitat, population size, and vocalizations
(Eisermann et al. 2011, in press). Within the
present study we gathered information on
how tanagers use the remaining habitat. We
examined preferences in nest site selection,
nesting season, and nest success. Nesting sites
are key elements for species conservation
(BirdLife International 2004). This is the first
compilation of nesting data for the Azure-
rumped Tanager in Guatemala, which is a
stronghold for the conservation of this
endangered species. Our observations pro-
vide a basis for recommendations for the
management of coffee plantations in order to
support the long-term survival of this species.
METHODS
Study area. The Azure-rumped Tanager’s area
of distribution in the western Pacific slope
mountains of Guatemala is characterized by a
chain of several major volcanoes. The altitudi-
nal belt between 1000 and 1900 m is charac-
terized by steep slopes of > 30%. The mean
annual rainfall in the entire distribution range
of the tanager in Guatemala amounts to
2000–4600 mm, but can locally reach a maxi-
mum of 6000 mm. The wet season extends
from April to November with a mean
monthly precipitation of 150–800 mm, and
the dry season from December to March with
mean monthly precipitation 5–150 mm
(MAGA 2002). Annual mean minimum tem-
41
NESTING OF AZURE-RUMPED TANAGER
perature is 15ºC; annual mean maximum is
25ºC (MAGA 2002). Landcover in the entire
range of Azure-rumped Tanager in Guate-
mala is dominated by coffee plantations
(68%), humid broadleaf forest (21%), scrub
and secondary forest (3.2%), mixed broadleaf-
coniferous forest (2.4%), and corn fields
(1.6%) (Eisermann et al. 2011).
We conducted nest searches on the south-
eastern slope of Atitlán volcano (14º32’N,
91º10’W), in an area which included parts of
the private nature reserves Los Tarrales, Los
Andes, and San Jerónimo Miramar, dpto.
Suchitepéquez. The natural climax vegetation
in this area is humid evergreen broadleaf for-
est, and broadleaf-coniferous forest in higher
and less humid areas. Landcover in a rectangle
of 1950 ha encompassing all trails used for
nest searches was as follows: broadleaf forest
1411 ha (72% of the study area), intensive
coffee plantations 337 ha (17%), non-inten-
sive coffee plantations 105 ha (5%), other
intensive plantations (ponytail Beaucarnea recur-
vata, tea Camellia sinensis, and others) 59 ha
(3%), scrub 12 ha (1%), and orchard-like set-
tlements 14 ha (1%) (Eisermann et al. 2011).
All coffee plantations within the study area
were shaded monocultures according to a
classification by Philpott et al. (2008), with a
shade cover of 10–30% and 1–5 species of
shade trees. Within the study area, we discrim-
inated between intensive and non-intensive
coffee plantations, classified by differences in
shade coverage and density of coffee shrubs.
Non-intensive coffee plantations had a low
density (10–20%) of coffee shrubs in the
understory, where they compete with native
shrubs and herbs. Herbs were absent in inten-
sive coffee plantations because of the inten-
sive use of herbicides, and coffee shrubs
covered about 50% of the understory. In non-
intensive plantations, the 15 m tall canopy of
shade trees, with coverage of 20–30%, was
dominated by Inga trees. Coverage of shade
trees in intensive coffee plantations was 10–
20% and Inga trees were heavily pruned, and
these plantations also had non-native species
of shade trees (Acrocarpus fraxinifolius, Eucalyp-
tus sp.).
Nest searches. Nest searches were carried out by
walking along trails watching out for territo-
rial and/or nesting behaviors. Detectability of
Azure-rumped Tanager vocalizations was
high over a distance of 30 m (Eisermann et al.
2011). Total trail length was 18.4 km; thus,
with the total strip width of sampled habitat
being 60 m, the total areas of sampled habitats
were as follows: 66 ha of broadleaf forest, 19
ha of non-intensive coffee plantation and
orchard-like settlement, and 25 ha of intensive
coffee plantation. Searches were conducted
over a period of 17 months from May 2008 to
September 2009. To determine nesting season
and nest success, nests were revisited at mean
intervals of 2.6 ± 3.6 days (SD) (range 1–22
days) and observed between 30 min and 10 h
in each session. We used 8× and 10× binocu-
lars and a 20–60× spotting scope to observe
the nests from a distance. Tanagers did not
appear to be sensitive to human presence at a
distance of more than 30 m from the nest. We
recorded the time that tanagers spent incubat-
ing, their feeding rates, and the food items
brought to the nest. Genders were not distin-
guishable from our observation posts.
In addition to the nests encountered dur-
ing the study period, we compiled data from
nests previously encountered during occa-
sional observations. Geographic coordinates
and elevation of nesting sites were determined
with a handheld GPS device (Garmin 60CSx)
with an accuracy of 5 m. We measured the dis-
tance to the forest edge using a Laser field
ranger (Nikon ProStaff Laser 440) at close
range with an accuracy of 1 m, or in cases
where the forest edge was out of view it was
determined based on orthoimages from
December 2005 (MAGA 2010) with an accu-
racy of 5 m combined with ground-truthing.
42
EISERMANN ET AL.
Nest and tree height was determined with
a Laser field ranger. Because nests were
located high in the trees, the number of eggs
could not be determined. Causes of nest fail-
ure remained unknown, with a few excep-
tions.
Trees with tanager nests were identified
based on Standley & Steyermark (1946 and
following volumes) and Parker (2008), taking
into account recent taxonomic revisions (Berg
2007, de Laubenfels 2009). Voucher speci-
mens were archived in the herbarium BIGU,
School of Biology of San Carlos University,
and in the herbarium AGUAT, Faculty of
Agronomy of the San Carlos University, both
located in Guatemala City.
Vegetation structure. We produced foliage-height
profiles of the nest surroundings modified
after Blondel & Cuvillier (1977) by determin-
ing vegetation density in 20 strata. We used a
9 m long telescopic pole which was marked
from 0.5 to 9 m, and a Laser field ranger. At
nesting sites, between two and six evenly
spaced radial lines were laid out at each nest
tree. Foliage coverage was measured at the
radii of 10, 20, and 30 m. At each point the
telescopic pole was positioned vertically, not-
ing whether plants touched the pole on marks
at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, and 9 m.
Above this height, we used the Laser field
ranger to determine whether plants touched
at the imaginary elongation of the pole at 10,
12, 15, 20, 25, 30, 35, and 40 m. All measure-
ments were taken by the same observer (KE).
The percentage of the number of touches of
plant in the different strata was used as a veg-
etation density index. Measurements were
taken after nesting had finished or after nest
failure was noticed, in order to avoid distur-
bance at nest sites.
Statistical analyses. To determine nest habitat
preferences of the Azure-rumped Tanager,
we used a Chi-Square Goodness of Fit test to
compare the numbers of nests detected in
each habitat. Expected numbers of nests were
calculated based on the area sampled as
equivalent to expected proportions. Because
one expected value was < 5, we applied a
Monte Carlo simulation of the multinomial
sampling distribution with 10,000 random
samples using software VassarStat (Lowry
2010). The extension of the Fisher test (per-
mutation test) with α = 0.05, computed with
SsS software (Engel 1998), was used to calcu-
late the significance of nest tree selection
divided into two categories of nest success
(fledged/unknown, failed) for each tree spe-
cies. The mean vegetation density between
nesting sites was compared using a random-
ization test with α = 0.05, computed with SsS
software (Engel 1998).
Because nests were high in trees, we were
unable to see the nest contents. We derived
dates of the first egg laid and young hatched
from the adults’ behavior. We calculated nest
success for the period from onset of incuba-
tion to fledging of the first young. Because
the total number of nests was rather small, we
used the Mayfield (1961, 1975) method to cal-
culate nest success, which is adequate for
small sample sizes (Johnson 2007). The daily
survival probability (s) was calculated by: s =
(ND – losses)/ND, where ND is number of
nest days of exposure and losses is number of
failed nests (Mayfield 1975). Survival proba-
bility for the nesting cycle from onset of incu-
bation to fledging of the first young was
calculated by (Daily Survival Probability)t,
where t is number of days of incubation and
brood rearing. Variance (V) of the estimated
survival probability (s) was calculated by V =
[(ND – losses) x losses]/ND3 (Johnson 1979),
the standard error (SE) being the square root
of variance. Approximate 95% confidence
limits were calculated by s ± 2SE (Johnson
1979).
Incubation constancy was calculated
according to Skutch (1962): T = 100 x S/
43
NESTING OF AZURE-RUMPED TANAGER
(S+R), where T is percentage of time spent
incubating, S is mean duration of incubation
sessions, and R is mean duration of recesses.
Mean number of nest visits by adults was
compared with a randomization test with α =
0.05 using SsS software (Engel 1998).
RESULTS
Nesting sites. Thirty-two nests of Azure-
rumped Tanager were recorded in Guatemala
from 2001–2009, of which 30 were observed
at Atitlán volcano, one in Unión Victoria,
Mun. Pochuta, dpto. Chimaltenango (D. Ruby,
pers. com.), and one at Finca Los Pirineos,
Mun. El Palmar, dpto. Quetzaltenango (J.
Berry, pers. com.). All nests were cup-shaped
and located in the upper part of trees with a
diameter at breast height (DBH) > 33 cm.
Most of the nests were located in a fork of a
branch, and some of them were also sup-
ported by epiphytic ferns and orchids (Fig. 1).
The mean elevation (± SD) of all nesting sites
was 1459 ± 210 m (n = 32), with the lowest
nest found at 860 m and the highest one at
1850 m (Appendix).
Fifteen nests were located in broadleaf
forest. Mean distance (± SD) from the forest
edge was 174 ± 242 m (range 0–700 m). Four
of these nests were located in the forest inte-
rior > 400 m from the forest edge. Another
13 nests were located in non-intensive coffee
plantation, two in intensive coffee plantation,
and two in orchard-like settlement. The mean
distance (± SD) to the nearest forest edge of
these 17 nests was 40 ± 28 m (range 5–130
m).
Along transects 25 nests were detected, 13
nests in forest (2.0 nests 10 ha-1), 10 in non-
intensive coffee plantation and orchard-like
settlement (5.3 nests 10 ha-1), and 2 in inten-
sive coffee plantation (0.8 nests 10 ha-1). Sig-
nificantly more nests were found in non-
intensive coffee plantation (combined with
number of nests in orchard-like settlement)
(χ2 = 10.13, df = 2, P < 0.01, based on Monte
Carlo simulation of the multinomial sampling
distribution with 10000 random samples).
Vegetation structure within a radius of 30
m around nest trees differed greatly among
nesting sites (Fig. 2). Azure-rumped tanagers
also nested successfully on sites with greatly
reduced or absent upper canopy of native
broadleaf trees (Fig. 3). Taking into account
the four successful nests from Fig. 3, mean
vegetation coverage in the canopy and mid-
story were significantly different between
coffee plantation and forest: canopy (ran-
domization test, difference in means 0.32, P
< 0.005, n = 500 permutations), midstory
(randomization test, difference in means 0.31,
P < 0.05, n = 500 permutations), and under-
story (randomization test, difference in means
0.02, P = 0.85, n = 500 permutations). This
indicates that the tanager’s successful nesting
is independent from certain vegetation struc-
tures. Tanagers were also generalists in their
nest tree selection; the 32 nests were located
in 20 different tree species (Appendix),
among them a conifer (Neocupressus lusitanica)
and two introduced, non-native species (Acro-
carpus fraxinifolius, Eucalyptus sp.). The number
of nests per tree species, classified by two cat-
egories (fledged/unknown, failed) was not
significantly different (extension of Fisher
test: n = 669,999 permutations, P = 0.1).
Mean nest height (± SD) above ground was
21 ± 12 m (range 7.5–68 m, n = 30). Mean
relative nest height (± SD) in the nest trees
was 78% ± 26, with lowest nests located at
44% of tree height and highest nests being in
the tree top level.
At two nest sites, nesting was recorded
several times in subsequent years, suggesting
nest site fidelity. Nests 21 and 32 were located
in the same tree in 2008 and 2009 respectively.
Nests 3, 5, 6, 7, 8, 9, 24, and 25 were in the
same general area with the greatest distance
between nest trees of 65 m. In five cases, nest-
ing attempts were recorded near nests which
44
EISERMANN ET AL.
had been abandoned shortly before, probably
indicating repeated nesting attempts after nest
failure: nest 9 after nest 8 in a distance of 15
m, nest 25 after nest 24, and nest 31 after nest
30. The shortest distance between synchroni-
cally active nests was 40 m (nest 11 and nest
12).
Nesting season. Nesting of Azure-rumped tana-
gers was observed in all months from April
through September. Nest 2 was the earliest
nest, with nest-building observed on 14 April,
followed by nest 14 with an adult incubating
on 25 April. This nest must have been built in
the second or third week of April. Latest
nests were nest 21 with eggs presumably
hatched on 28 August, and nest 7 with adults
feeding young only a few days old on 8 Sep-
tember. The nestlings would have fledged in
the last week of September. The nesting sea-
son coincided with the wet season (Fig. 4).
Nest attendance. At nest 9, located in a non-
intensive coffee plantation 30 m from the
border of broadleaf forest, we were able to
observe the timing of nesting activity through
all stages.
The nest was attended by three adults (the
pair and a helper) from the beginning of nest-
building on 11 July 2009 to fledging on 18
August 2009. Nest-building took six days
(11–16 July). During 7.75 h (08:15–16:00 h
FIG. 1. Azure-rumped Tanager (Tangara cabanisi) nest sites at Atitlán volcano, Guatemala. a) Nest 9 in Neo-
cupressus lusitanica (arrows pointing to the nest and to the adult, of which breast and belly are visible), phase
of nest-building, 13 July 2008. b) Nest 21 supported by epiphytic ferns and orchids in branches of Ficus
aurea, adult in nest (arrow pointing to the bill), 7 September 2008. c) Nest 12 in Aegiphila valerioi, adult incu-
bating, 6 August 2008. d) Nest 13 in Cecropia obtusifolia, caudoventral view at the adult standing on nest rim,
7 August 2008. Photos: K. Eisermann.
45
NESTING OF AZURE-RUMPED TANAGER
FIG. 2. Foliage height profiles of nest sites of Azure-rumped Tanager (Tangara cabanisi) in broadleaf forest,
non-intensive, and intensive coffee plantations (n1 = number of nest sites, n2 = number of points where
vegetation cover was measured) at Atitlán volcano, Guatemala, 2008–2009. Data from 23 nests are
included. Data from nest sites at the edge between different habitats were treated in each habitat class sep-
arately. Percent cover represents the mean percentage of plant touches on a pole in the indicated height
classes.
46
EISERMANN ET AL.
FIG. 3. Foliage height profiles in four successful nests of Azure-rumped Tanager (Tangara cabanisi) at Ati-
tlán volcano, Guatemala, 2008–2009, two in broadleaf forest, one in intensive coffee plantation, and one
on the edge between non-intensive coffee plantation and secondary growth (n = number of points where
vegetation cover was measured).
47
NESTING OF AZURE-RUMPED TANAGER
CST) of observation on 13 July, adults went
23 times (on average once every 20 min) to
the nest tree for nest-building. We observed
tanagers collecting and carrying moss, lichen,
rootlets of small epiphytic ferns (Pleopeltis
angusta), and soft cotton-like material for nest-
building. Material was collected in the nest
tree and in trees up to 30 m or more from the
nest tree. Repeated copulations in or near the
nest tree were observed on 13 and 14 July.
Once the helper approached the pair closely
during copulation, but the male chased the
helper away. We were unable to see inside the
nest cup, but based on prolonged stays of an
adult in the nest on the sixth day (16 July), we
assume that this was the day the first of pre-
sumably two eggs was laid. The incubation
period began on 17 July and lasted for 14 days
FIG. 4. Nesting season of Azure-rumped Tanager (Tangara cabanisi) in Guatemala ranged from April to
September and coincided with the wet season. a) Timing of 30 nests encountered with at least one obser-
v
ation of adults attending the nest. b) Time of egg laying on 19 nests (columns) and mean monthly
amount of rainfall (triangles: data from the weather station in the Los Tarrales Reserve, 1989–2009; Insti-
tuto Nacional de Sismología, Vulcanología, Meteorología e Hidrología INSIVUMEH, unpubl. data).
48
EISERMANN ET AL.
(until 31 July). During 14 hours of observa-
tion on 7 days, incubation constancy was 76%
and the mean length (± SD) of incubation
sessions was 23 ± 15 min (n = 22, range 1–58
min), and recess lasted 7 ± 5 min (n = 27,
range 1–21 min). During the incubation
period, an adult was occasionally observed
feeding the incubating adult. Brooding lasted
for 17 days (31 July–17 August). During 35
hours of observation on 12 days (2–18
August), mean number of nest visits (± SD)
per hour of adult birds including helper was
11.2 ± 7.0 (n = 368 visits). The helper, distin-
guished by a less intensive dark spotting on
the chest plumage, visited 1.7 ± 1.8 times per
hour (n = 69). Occasionally, the helper did
not join the other adults on flights to bring
food, instead staying near the nesting tree.
Adults were frequently seen with their bills
full of pieces of red fruit of Ficus spp. and
imagos of sciarid flies (Diptera: Sciaridae)
which were abundant in the foliage of Inga
micheliana shade trees. Adults were also seen
collecting unidentified green Lepidoptera lar-
vae from the leaves of I. micheliana. The first
juvenile fledged on 17 August at 10:00 h, the
second left the nest on the following morning
at 07:50 h. On that day the young birds
moved in a radius of 30 m around the nest
tree. On 19 August the young were seen at 50
m from the nest tree, and on 20 August at
about 100 m.
Nest 12 was located in broadleaf forest,
and incubation constancy there was 68%,
with incubation sessions of 17 ± 8 min (n =
20) and recesses of 8 ± 6 min (n = 22). Nest
23 was a successful brood without helper at
the nest. During 16.25 hours of observation
on 7 days (29 May–11 June 2009), mean num-
ber of nest visits (± SD) per hour of adult
birds was 8.2 ± 1.2 (n = 140 visits). Mean
number of visits of adult birds to nest 23 was
not significantly lower than at nest 9, where a
helper assisted (randomization test, difference
in means 3.038, P = 0.2), and also counting
exclusively visits of the parent birds (random-
ization test, difference in means 1.298, P =
0.6). Helpers were recorded at only two of
eight nests (nest 9 and nest 27) where feeding
adults were observed on several dates for sev-
eral hours.
Nest success. Nest success among 32 encoun-
tered nests was rather low. Incubating or feed-
ing adults were recorded at 20 nests, and for
12 nests it remained unknown if eggs were
laid. Of the 20 nests where eggs had been
laid, data of repeated visits were collected at
18 nests. Using the Mayfield (1961, 1975)
method, daily survival probability (s) of these
18 nests was 0.94 ± 0.02 (SE). Using a nesting
period of 31 days from onset of incubation to
fledging of the first young (based on data
from Nest 9), survival probability for the
entire nesting period was 0.16 (0.943531).
Thus nest success was 16% (95% confidence
interval: 5–45%).
The cause of nest failure could not be
determined for any of these nests. At nest 21,
the young died in the nest for an unknown
reason. A day after adults were observed feed-
ing the nestlings, an adult stayed in the nest
without feeding for 3 h. Through the spotting
scope we saw from a distance a large wasp
(Hymenoptera) and shortly after a fly
(Diptera) entering the nest (KE and GL, pers.
obs.), indicating that dead nestlings were
probably there. At nest 12, an Emerald Tou-
canet (Aulacorhynchus prasinus) was seen on 6
August 2008 perched in the canopy at a dis-
tance of about 5 m from the tanager nest,
apparently observing the nest. A day later the
nest was abandoned, presumably predated.
The Bushy-crested Jay (Cyanocorax melanocya-
neus) was the only bird species we observed
depredating on the Azure-rumped Tanager.
On 19 August 2009, two jays were seen in the
canopy of broadleaf forest at 1750 m, one of
them carried in its bill a young Azure-rumped
Tanager with half grown flight feathers, de-
49
NESTING OF AZURE-RUMPED TANAGER
predated from an unknown nest (ALL and
GL pers. observ.). Two adult tanagers were
mobbing the jays.
Noteworthy behavioral observations. One pair
of Azure-rumped tanagers was observed
constructing two nests synchronously (SA &
GL pers. observ.). On 1 August 2008, nest 15
was found at construction stage. On 8
August, the pair was still nest-building. In
addition to the nest observed a week earlier, a
second nest was built 1 m apart from the first
nest. During 2.5 h of observation (08:25–
10:55 h), 17 visits were recorded for one of
the nests and 19 for the other. The pair
moved together back and forth to bring nest
material, but each bird to a different nest. On
one visit, both birds went together to the sec-
ond nest, and on another visit they went first
to each other’s nest and gathered then at the
new nest. The outcome of this nesting
attempt remains unknown.
Incubating adults were repeatedly
observed calling. A soft pip-call was given
apparently as a contact call. Sometimes a loud
and excited trill was given, apparently to com-
municate with the other parent and the
helper, or in response to other birds intruding
the general nest area.
Azure-rumped tanagers showed different
reactions to intruders of other bird species in
the nest territory. Sometimes they ignored the
close approach of Paltry Tyrannulet (Zimmerius
vilissimus), Yellow-winged Tanager (Thraupis
abbas), and Blue-tailed Hummingbird (Ama-
zilia cyanura), and did not react at all. In most
cases, however, they chased intruding small
birds away, including Paltry Tyrannulet, Band-
backed Wren (Campylorhynchus zonatus),
Rufous-and-white Wren (Thryothorus rufalbus),
Brown-backed Solitaire (Myadestes occidentalis),
Black-and-white Warbler (Mniotilta varia),
Slate-throated Redstart (Myioborus miniatus),
Yellow-winged Tanager, White-winged Tana-
ger (Piranga leucoptera), and Lesser Goldfinch
(Spinus psaltria). Adults became alert, jumping
nervously between twigs when flocks of call-
ing Pacific parakeets (Aratinga strenua) were
flying high overhead. Adult tanagers observed
alertly Bushy-crested jays and Emerald touca-
nets moving near the nesting territory. Once
they stopped a routine of intensive feeding
when a flock of Bushy-crested jays was in the
nest territory. They avoided approaching their
nest and feeding their young until the jays
were gone.
DISCUSSION
Nesting sites and nesting season. The Azure-
rumped Tanager has been reported to be a
specialist of humid broadleaf forest from Chi-
apas (Heath & Long 1991) and Guatemala
(Eisermann et al. 2011). Nesting had previ-
ously been reported only from forest habitats
(Long & Heath 1994, Gómez de Silva Garza
1997). Thus, nesting in coffee plantations in
our study area at Atitlán volcano is notewor-
thy and suggests that the species may in fact
be adapted to disturbance. The number of
nests 10 ha-1 was highest in non-intensive cof-
fee plantation. A preference of non-intensive
coffee plantation over forest can not be con-
cluded, because nest detectability is likely
much lower in the taller and denser forest
than in non-intensive coffee plantation. Note-
worthy, however, is the greater number of
nests 10 ha-1 in non-intensive coffee planta-
tion compared to intensive coffee plantation.
Nest detectability can be expected to be
higher in intensive plantations because of a
less dense vegetation structure (Fig. 2). Nest-
ing outside the prime habitat could be caused
by increased competition for nesting sites
because of forest fragmentation, including
interspecific competition (Martin & Martin
2001). Potential competitors of the Azure-
rumped Tanager could be the sympatric Yel-
low-winged Tanager and Blue-gray Tanager
(Thraupis episcopus). There might also exist
50
EISERMANN ET AL.
some advantages of nesting sites in planta-
tions, such as lower predation pressure or
competition, thus combining favorable nest
sites with favorable foraging sites in nearby
forest. Available data on causes of nest failure
in Azure-rumped Tanager are insufficient to
address these questions.
Nesting of the Azure-rumped Tanager
was previously recorded at 1200–1500 m
(Long & Heath 1994, Gómez de Silva Garza
1997). Recent census data from Atitlán vol-
cano showed that the tanager prefers forest at
elevations 1400–1900 over forests at 900–
1300 m (Eisermann et al. 2011). Our observa-
tions of nest sites in the same area, combined
with census data (Eisermann et al. 2011),
expand the altitudinal range of records to
860–1900 m.
In Chiapas, nesting activity was observed
from April to June, based on observations in
all months except January, July, and August
(Long & Heath 1994). Based on more exten-
sive observations in all months at Atitlán vol-
cano we recorded nesting from April to
September. The relatively long nesting season
might include more than one brood per sea-
son, which has also been reported from con-
geners, such as Golden-hooded (Tangara
larvata) (3 broods), Bay-headed (T. gyrola) (3
broods), and Silver-throated Tanager (T. ictero-
cephala) (2 broods) (Skutch 1954, 1981). At
Atitlán volcano, nesting season seems to be
linked with the fruiting season of Ficus aurea, a
common tree in this forest providing large
fruit (1–2 cm in diameter) as a food source.
Most observations of feeding tanagers along
transect counts during the nesting season
were made on this tree species (Eisermann et
al. 2011). In Chiapas, Long & Heath (1994)
reported a linkage between the tanager and
Ficus cookii, which belongs to the species
group of Ficus aurea (Berg 2007).
Nest attendance and nest success. While the nest-
ing season of Azure-rumped tanagers was
longer and nesting sites more variable in
Guatemala than previously reported from
Chiapas, nest attendance by adults was similar
to observations in Chiapas (Long & Heath
1994) and indeed very similar to other Tangara
species. Nest-building at one nest at Atitlán
volcano took 6 days. Skutch (1954) reported a
period of 4–12 days for the Golden-hooded
Tanager and Wood et al. (1992) at least 8
days in the Paradise Tanager (Tangara chilensis).
The incubation period of 14 days agrees
with other studies of Tangara species with
incubation periods of 13–17 days (Golden-
hooded, Bay-headed, and Speckled Tanager
T. guttata, Skutch 1954; Azure-rumped Tana-
ger; Long & Heath 1994; Paradise Tanager,
Wood et al. 1992; Black-capped Tanager T.
heinei, Freeman & Greeney 2009). Incubation
constancy at two nests at Atitlán volcano
was 68% and 76% respectively, similar to
two nests in Chiapas with 74% and 82%
(Long & Heath 1994), and similar to
congeners with incubation constancies 65–
82% (Golden-hooded, Speckled, and Silver-
throated Tanager, Skutch 1954; Black-capped
Tanager, Freeman & Greeney 2009). Incuba-
tion sessions of between a few minutes and
an hour are common (Skutch 1954, Long &
Heath 1991, Wood et al. 1992, Freeman &
Greeney 2009), the longest session of 134
min was observed in the Bay-headed Tanager
(Skutch 1954). Brooding lasted 17 days at a
nest at Atitlán, which is longer than reported
from Chiapas (15 days; Long & Heath 1994)
or from other congeners (14–16 days in
Golden-hooded and 15–16 days in Bay-
headed Tanager, Skutch 1954; 14 days in
Golden Tanager, Gelis et al. 2006). Feeding
rates of the Azure-rumped Tanager of 8–11
nest visits per hour were similar to Golden-
hooded (9–16 visits h-1) and Speckled (5 visits
h-1; Skutch 1954), Beryl-spangled (4–12 visits
h-1; Sheldon & Greeney 2007), and Black-
capped Tanager (6 feeds h-1 per nestling;
Freeman & Greeney 2009).
51
NESTING OF AZURE-RUMPED TANAGER
During nest watches, genders of Azure-
rumped Tanager were not distinguishable
from a distance. However, we observed occa-
sional feeding of an incubating adult by a sec-
ond adult. According to observations on
other passerines (Skutch 1957), occasional
feeding of the incubating adult by its partner
indicates that only the female incubates. This
behavior has been found in a number of con-
geners, such as Golden-hooded, Speckled,
Plain-colored (T. inornata), Bay-headed, Silver-
throated (Skutch 1954), Flame-faced (T. par-
zudakii) (Arcos-Torres & Solano-Ugalde
2007), and Black-capped Tanager (Freeman &
Greeney 2009).
We observed cooperative breeding on two
of eight nests with extensive observations of
attending adults. Helpers at the nest have
been reported previously for at least 10 tana-
ger species (Thraupidae sensu American Orni-
thologists’ Union 1998, Chesser et al. 2010)
(Skutch 1954, Brown 1987, Alves 1990,
Skutch 1999, Gelis et al. 2006), including the
Azure-rumped Tanager (Long & Heath 1994).
Benefits of cooperatively breeding are mani-
fold and include increased productivity,
improved territory defense, load-lightening
for parents, learning of skills, access to mates,
and territories for helpers (Cockburn 1998).
We observed no significant difference in the
number of nest visits by parent birds during
brood rearing between a nest with helper and
a nest without helper. The helper, however,
was observed to stay occasionally in the nest
territory, thus apparently benefiting nest
defense. As flights between the nest and food
sources become longer, parent birds spend
consequently more time traveling and less
time defending the nest.
Noteworthy was the vocalization activity
of incubating Azure-rumped tanagers,
because incubating passerine birds usually
remain motionless in order to escape the
detection by predators (Deeming 2002). Calls
of incubating Azure-rumped tanagers have
also been reported from Chiapas (Long &
Heath 1991). In Paradise tanagers, Wood et al.
(1992) observed calling birds only at some
distance from the nest. Libsch et al. (2008)
showed in several Neotropical passerine spe-
cies that nest predation occurs usually during
daytime. In addition, predation risk increases
with parental activity (Martin et al. 2000).
Vocalizations of incubating Azure-rumped
tanagers might call the attention of predators
in the same way as it called our attention to
locate nests. We suspect, however, that the
function of these vocalizations is to improve
nest defense by communication between par-
ents and helpers. Long & Heath (1994) sup-
posed that social groups of tanagers could
feed more than one brood at a time. The
marking of individuals could reveal more data
on this specific social system.
Nest success of the Azure-rumped Tana-
ger was rather low at Atitlán volcano (5–45%
according the Mayfield method), which is not
unusual for Neotropical birds (Skutch 1985,
Robinson et al. 2000, Lindell & Smith 2003,
You ng et al. 2008). A comparison of our cal-
culation of nest success of the Azure-rumped
Tanager with other locations and congeners is
difficult because little information is available.
Long & Heath (1994) supposed that young
fledged from 29–43% of the nests (2–3 of 7
nests) in Chiapas. Skutch (1981) reported suc-
cess in 10 of 35 nests (24%) of Golden-
hooded Tanager and 19 of 35 (54%) in Silver-
throated Tanager. Using an uncorrected calcu-
lation similar to Skutch (1981) and Long &
Heath (1994), 4 of 18 (22%) encountered
nests at Atitlán volcano were successful, 4
(22%) had an unknown fate, and 12 (66%)
failed. Consequently, maximum number of
successful nests was 44%. In addition to pred-
ators, such as the Bushy-crested Jay, mam-
mals, and snakes, the open-cup canopy nests
of Azure-rumped tanagers are exposed to tor-
rential rain storms as potential threat. How
the different nesting habitats, e.g., forest vs
52
EISERMANN ET AL.
coffee plantation, influence nesting success,
remains unknown. More nest observations
are required to address this question.
Conservation implications. Forests have been
reduced to only 21% of the Azure-rumped
Tanager’s potential area of distribution in
Guatemala, and coffee plantations cover
68% of this area (Eisermann et al. 2011).
Although it remains unknown if Azure-
rumped tanagers nest in coffee plantations
because of negative effects of broadleaf
forest fragmentation or for reason that the
species is ecologically more adaptable than
previously assumed, our data establish an
important base for practical conservation
measures for this endangered species. Coffee
plantations in close neighborhood to broad-
leaf forest can provide valuable habitat for the
tanager, as long as they have a well developed
canopy of shade trees (even a monoculture of
Inga trees) with some taller trees providing
nest sites and fruit trees as food source (espe-
cially trees of the Ficus aurea complex). We
found tanagers nesting only in canopy trees,
therefore only coffee plantations with shade
trees can provide potential nesting sites.
Moreover, tanagers were observed collecting
nest material (epiphytic mosses and rootlets)
near the nest site. Thus they can probably not
find sufficient nest material in intensively
managed coffee plantations without epiphytes
(Philpott et al. 2008), because of heavily
pruned shade trees and the extensive use of
herbicides. The following conservation mea-
sures are recommended to meet critical habi-
tat needs: 1) protection of existing broadleaf
forest in the potential area of distribution, 2)
reforestation with local broadleaf tree species,
3) enhancement of the structural complexity
of intensive coffee plantations by planting
trees, 4) recruitment of more landowners into
non-intensive coffee-growing schemes, and 5)
avoidance of the conversion of shaded to
unshaded coffee plantations. Habitat restora-
tion measures should be accompanied by
population monitoring of the Azure-rumped
Tanager.
The necessity of conservation efforts in
human-altered landscapes in Guatemala has
been recognized during the identification of
Important Bird Areas (Eisermann & Aven-
daño 2009a, b) and also on a regional scale
in Mesoamerica (Harvey et al. 2008, Chazdón
et al. 2009, Gardner et al. 2009). Since con-
servation is costly (Balmford & Whitten
2003), the Azure-rumped Tanager could be
used as a flagship and indicator species for
biodiversity-friendly management of coffee
plantations in the Chiapas and Guatemala
Pacific slope mountains. Maintaining shade
coffee plantations as habitat for the Azure-
rumped Tanager would certainly promote
biodiversity conservation on a broader scale
(Tejeda-Cruz & Sutherland 2004, Philpott et
al. 2008). The tanager could be incorporated
into local coffee certification schemes (Har-
vey et al. 2008).
Repeated nesting on the same nesting site
(same tree or tree nearby) by Azure-rumped
tanagers at Atitlán volcano over several years
suggests nest site fidelity, which can be veri-
fied by future studies using individually
marked birds. Nest site fidelity has also been
suggested in a pair of Grass-green Tanager
(Chlorornis riefferii; Greeney & Gelis 2006).
Known nesting sites should receive special
consideration by land owners. Based on the
Convention on International Trade in Endan-
gered Species of Wild Flora and Fauna
(CITES), threatened species are legally pro-
tected from illegal trade in Guatemala but the
country lacks a legal framework to protect
them from other threats, such as habitat
destruction and disturbances at nest sites.
This leaves a high responsibility on landown-
ers to enforce the protection of sensitive sites.
The Azure-rumped Tanager is a target species
for birdwatchers. Land owners, birding
guides, birdwatchers, and photographers
53
NESTING OF AZURE-RUMPED TANAGER
should take care that nests of Azure-rumped
tanagers are not approached closely, because
disturbance of nest sites could potentially lead
to reduced nest success and population
decline. Through birdwatching, however,
Azure-rumped Tanager can develop as a flag-
ship species for conservation, getting land-
owners to take pride in having the species
breeding on their land, thus encouraging habi-
tat protection, active nest-site protection, and
less intensive coffee-growing.
ACKNOWLEDGMENTS
SA, KE, and CA are grateful to Andy
Burge and Mónica Barrios for preparing a
temporary home at El Vesubio/Los Tarrales.
We thank Olga Hazard, Jaime Freire, Mark
Brissani, and Arnoldo Villagrán for granting
research permission in Los Andes and San
Jerónimo Miramar private reserves. We
appreciate the hospitality by Olga Hazard
and Jaime Freire and field assistance by
Jesús Lucas Yuxón, Juan Calvo Cortéz,
Carsten Loth, Juan Mejía, and Gilberto de
León. Jason Berry, Douglas E. Ruby, Aaron
H. Johnston, and Dan Davis contributed
additional nest data. We thank Juan José
Castillo Mont, Mario Veliz, and David Mendi-
eta for the identification of plant specimens,
and Enio Cano for the identification of
Diptera. The Instituto Nacional de Sismolo-
gía, Vulcanología, Meteorología e Hidrología
(INSIVUMEH) provided climate data. We
appreciate critical comments on the manu-
script by Oliver Komar, André Weller, and
two anonymous reviewers, and the revision
of English usage of an earlier version by
Peter Lowther through the Association of
Field Ornithologists’ program of editorial
assistance. Optics for the Tropics donated
binoculars. This study was financially sup-
ported by Cayaya Birding, Los Tarrales
Reser ve, and the PROEVAL RAXMU Bird
Monitoring Program.
REFERENCES
Alves, M. A. S. 1990. Social system and helping
behavior in the White-banded Tanager (Neo-
thraupis fasciata). Condor 92: 470–474.
Arcos-Torres, A., & A. Solano-Ugalde. 2007. Notas
sobre la anidación de tres especies del género
Tangara (Thraupidae: Aves) en el noroccidente
de Ecuador. Bol. SAO 17: 133–137.
American Ornithologists’ Union (AOU). 1998.
The American Ornithologists’ Union check-list
of North American birds. 7th ed. American
Ornithologists’ Union, Washington, D.C., USA.
Balmford, A., & T. Whitten 2003. Who should pay
for tropical conservation, and how the costs be
met? Oryx 37: 238–250.
Berg, C. C. 2007. Proposals for treating four spe-
cies complexes in Ficus subgenus urostigma sec-
tion americanae. Blumea 52: 295–312.
BirdLife International. 2004. State of the world’s
birds 2004: indicators for our changing world.
BirdLife International, Cambridge, UK.
BirdLife International [online]. 2008. Species fact
sheet: Tangara cabanisi. Dowloaded on 17 June
2008 from http://www.birdlife.org/datazone/
species/index.html.
Blondel, J., & R. Cuvillier. 1977. Une méthode sim-
ple et rapide pour décrire les habitat d’oiseaux:
le stratiscope. Oikos 29: 326–331.
Brodkorb, P. 1939. Rediscovery of Heleodytes chiapen-
sis and Tangara cabanisi. Auk 56: 447–450.
Brown, J. L. 1987. Helping and communal breeding
in birds: ecology and evolution. Princeton Univ.
Press, Princeton, New Jersey, USA.
Chazdon, R. L., C. A. Harvey, O. Komar, D. M.
Griffith, B. G. Ferguson, M. Martínez-Ramos,
H. Morales, R. Nigh, L. Soto-Pinto, M. van
Breugel, & S. M. Philpott. 2009. Beyond
reserves: a research agenda for conserving
biodiversity in human-modified tropical land-
scapes. Biotropica 41: 142–153.
Chesser, R. T., R. C. Banks, F. K. Barker, C. Cicero,
J. L. Dunn, A. W. Kratter, I. J. Lovette, P. C.
Rasmussen, J. V. Remsen, Jr., J. D. Rising, D. F.
Stotz, & K. Winker. 2010. Fifty-first supple-
ment to the American Ornithologists’ Union
check-list of North American birds. Auk 127:
726–744.
Cockburn, A. 1998. Evolution of helping behavior
54
EISERMANN ET AL.
in cooperatively breeding birds. Annu. Rev.
Ecol. Syst. 29: 141–177.
Collar, N. J., L. P. Gonzaga, N. Krabbe, A.
Madroño Nieto, L. G. Naranjo, T. A. Parker III,
& D. C. Wege. 1992. Threatened birds of the
Americas: the ICBP/IUCN Red Data Book.
Smithsonian Institution Press, Washington,
D.C., USA and International Council for Bird
Preservation, Cambridge, UK.
Cooper, D. S. 2003. New distributional and ecolog-
ical information on birds in south-western
Guatemala. Cotinga 19: 61–63.
de Laubenfels, D. J. 2009. Nomenclatural actions
for the New World cypresses (Cupressaceae).
Novon 19: 300–306.
Deeming, D. C. 2002. Behaviour patterns during
incubation. Pp. 63–87 in Deeming, D. C. (ed.)
Avian incubation, behaviour, environment, and
evolution. Oxford Univ. Press, New York, New
Yor k, US A .
Eisermann, K., & C. Avendaño. 2007. Lista
comentada de las aves de Guatemala - Anno-
tated checklist of the birds of Guatemala. Lynx
Edicions, Barcelona, Spain.
Eisermann, K., & C. Avendaño. 2009a. Conserva-
tion priority-setting in Guatemala through the
identification of Important Bird Areas. Pro-
ceedings of the Fourth International Partners
in Flight Conference, Tundra to Tropics: 315–
327.
Eisermann, K., & C. Avendaño. 2009b. Guatemala.
Pp. 235–242 in Devenish, C., D. F. Diaz
Fernández, R. P. Clay, I. Davidson, & I. Yépez
Zabala (eds) Important Bird Areas Americas,
priority sites for biodiversity conservation.
BirdLife Conservation Series 16. Birdlife Inter-
national, Quito, Ecuador.
Eisermann, K., S. Arbeiter, G. López, C.
Avendaño, & J. de León Lux. 2011. Distribu-
tion, habitat use, and implications for the
conservation of the globally threatened
Azure-rumped Tanager Tangara cabanisi in
Guatemala. Bird Conserv. Int. 21: doi:10.1017/
S0959270910000638.
Eisermann, K., G. López, J. Ber r y, J. d e L e ó n L ux,
& A. Burge in press. Vocalisations and juvenile
plumage of the Azure-rumped Tanager.
Cotinga 33: – .
Engel, J. 1998. SsS. Rubisoft Software, Eichenau,
Germany.
Freeman, B. G., & H. F. Greeney. 2009. Parental
care of the Black-capped Tanager (Tangara hei-
nei) in northeastern Ecuador. Bol. SAO 19: 32–
37.
Gardner, T. A., J. Barlow, R. Chazdon, R. M.
Ewers, C. A. Harvey, C. A. Peres, & N. S. Sodhi
2009. Prospects for tropical forest biodiversity
in a human-modified world. Ecol. Lett. 12:
561–582.
Gelis, R. A., H. F. Greeney, & C. Dingle. 2006.
Cooperative breeding and first nest description
for Golden Tanager Tangara arthus. Cotinga 26:
79–81.
Gómez de Silva Garza, H. 1997. Further observa-
tions on the nesting of the Azure-rumped Tan-
ager. Bull. Br. Ornithol. Club 117: 16–18.
Greeney, H. F., & R. A. Gelis. 2006. Two nests of
Grass-green Tanager Chlorornis riefferii on the
ground. Cotinga 25: 86.
Harvey, C. A., O. Komar, R. Chazdon, B. G. Fergu-
son, B. Finegan, D. M. Griffith, M. Martínez-
Ramos, H. Morales, R. Nigh, L. Soto-Pinto, M.
van Breugel, & M. Wishnie 2008. Integrating
agricultural landscapes with biodiversity con-
servation in the Mesoamerican hotspot. Con-
serv. Biol. 22: 8–15.
Heath, M., & A. Long. 1991. Habitat, distribution
and status of the Azure-rumped Tanager Tan-
gara cabanisi in Mexico. Bird Conserv. Int. 1:
223–254.
Hilty, S. L., & D. Simon. 1977. The Azure-rumped
Tanager in Mexico with comparative remarks
on the Gray-and-gold Tanager. Auk 94: 605–
606.
Isler, M. L., & P. R. Isler 1987. The tanagers: natu-
ral history, distribution and identification.
Smithsonian Institution Press, Washington,
D.C., US A .
Johnson, D. H. 1979. Estimating nest success: the
Mayfield method and an alternative. Auk 96:
651–661.
Johnson, D. H. 2007. Estimating nest success: a
guide to the methods. Stud.Avian Biol. 34: 65–
72.
Libsch, M. M., C. Batista, D. Buehler, I. Ochoa, J.
Brawn, & R. E. Ricklefs. 2008. Nest predation
in a Neotropical forest occurs during daytime.
Condor 110: 166–170.
55
NESTING OF AZURE-RUMPED TANAGER
Lindell, C., & M. Smith. 2003. Nesting bird species
in sun coffee, pasture, and understory forest in
southern Costa Rica. Biodivers. Conserv. 12:
423–440.
Long, A. J., & M. F. Heath. 1994. Nesting ecology
and helping behavior in the Azure-rumped
Tanager in Mexico. Condor 96: 1095–1099.
Lowry, R. [online]. 2010. VassarStats: website for
statistical computation. Downloaded on 9
November 2010 from http://faculty.vassar.
edu/lowry/VassarStats.html.
MAGA. 2002. Atlas de Guatemala. CD-Rom. Mi-
nisterio de Agricultura, Ganadería y Alimen-
tación (MAGA), Guatemala City, Guatemala.
MAGA in press. Obtención de imagenes digtales
de la República de Guatemala del año 2006.
Ministerio de Agricultura Ganadería y Alimen-
tación (MAGA), Guatemala City, Guatemala
Martin, P. R., & T. E. Martin. 2001. Ecological and
fitness consequences of species coexistence: a
removal experiment with wood warblers. Ecol-
ogy 82: 189–206.
Martin, T. E., J. Scott, & C. Menge. 2000. Nest pre-
dation increases with parental activity: separat-
ing nest site and parental activity effects. Proc.
R. Soc. Lond. B 267: 2287–2293.
Mayfield, H. F. 1961. Nesting success calculated
from exposure. Wilson Bull. 73: 255–261.
Mayfield, H. F. 1975. Suggestions for estimating
nest success. Wilson Bull. 87: 456–466.
Parker, T. 2008. Trees of Guatemala. The Tree
Press, Austin, Texas, USA.
Parker III, T. A., S. Hilty, & M. Robbins. 1976.
Birds of the El Triunfo cloud forest, Mexico,
with notes on the Horned Guan and other spe-
cies. Am. Birds 30: 779–782.
Philpott, S. M., W. J. Arendt, I. Armbrecht, P.
Bichier, T. V. Diestch, C. Gordon, R. Green-
berg, I. Perfecto, R. Reynoso-Santos, L. Soto-
Pinto, C. Tejeda-Cruz, G. Williams-Linera, J.
Valenzuela, & J. M. Zolotoff. 2008. Biodiversity
loss in Latin American coffee landscapes:
review of the evidence on ants, birds, and trees.
Conserv. Biol. 22: 1093–1105.
Robinson, W. D., T. R. Robinson, S. K. Robinson,
& J. D. Brawn. 2000. Nesting success of under-
story forest birds in central Panama. J. Avian
Biol. 31: 151–164.
Sheldon, K. S., & H. F. Greeney. 2007. Nest and
parental care of the Beryl-spangled Tanager
(Tangara nigroviridis) in northeastern Ecuador.
Ornitol. Neotrop. 18: 603–606.
Skutch, A. F. 1954. Life histories of Central Ameri-
can birds, families Fringillidae, Thaupidae, Ic-
teridae, Parulidae and Coerebidae. Pac. Coast
Avifauna 31. Cooper Ornithological Society,
Berkeley, California, USA.
Skutch, A. F. 1957. The incubation patterns of
birds. Ibis 99: 69–93.
Skutch, A. F. 1962. The constancy of incubation.
Wilson Bull. 74: 115–152.
Skutch, A. F. 1981. New studies of tropical
America birds. Publ. Nuttall Ornithol. Club 19:
1–281.
Skutch, A. F. 1985. Clutch size, nesting success, and
predation on nests of Neotropical birds,
reviewed. Ornithol. Monogr. 36: 575–594.
Skutch, A. F. 1999. Helpers at birds’ nests: a world-
wide survey of cooperative breeding and
related behavior. Univ. of Iowa Press, Iowa City,
Iowa, USA.
Standley, P. C., & J. A. Steyermark. 1946. Flora of
Guatemala. Fieldiana: Botany Vol. 24, Part IV.
Chicago Natural History Museum, Chicago,
Illinois, USA.
Tejeda-Cruz, C., & W. J. Sutherland. 2004. Bird
responses to shade coffee production. Anim.
Conserv. 7: 169–179.
Wood, T., F. Gallo, & P. K. Donahue. 1992. Obser-
vations at a Paradise Tanager nest. Wilson Bull.
104: 360–362.
Young, B. E., T. W. Sherry, B. J. Sigel, & S. Wolt-
mann. 2008. Nesting success of Costa Rican
lowland rain forest birds in response to edge
and isolation effects. Biotropica 40: 615–622.
56
EISERMANN ET AL.
APPENDIX. Characteristics of nesting sites of the Azure-rumped Tanager in Guatemala. +Diameter at breast height of the tree trunk. *Nest tree over-
hanging at a very steep slope, numbers indicate tree height and in parenthesis height of tree top over ground. Habitat: BF = broadleaf forest; IC = intensive
coffee plantation; NIC = non-intensive coffee plantation; OS = orchard-like settlement; SF = secondary forest.
Nest Yea r Locality Elevation
(m a.s.l.)
Nest tree* (family) Habitat DBH
(cm)+
Tree height
(m)
Nest height
(m)
Distance to
forest edge (m)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
2001
2006
2006
2007
2007
2007
2007
2008
2008
2008
2008
2008
2008
2008
2008
2008
2008
2008
2008
Finca Los Pirineos
(14°41'N, 91°33'W)
Los Tarrales Reserve
(14°33'N 91°10'W)
Los Tarrales Reserve
Unión Victoria (formerly
Finca El Salvador)
(14°34'N, 91°03'W)
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Andes Reserve
(14°33'N, 91°11'W)
Los Tarrales Reserve
San Jerónimo Miramar
Reserve (14°34'N,
91°10'W)
Los Tarrales Reserve
Los Tarrales Reserve
1100
1510
1510
1260
1510
1510
1510
1510
1500
1480
1540
1540
1320
860
1700
1570
1460
1340
1820
Heliocarpus sp. (Tiliaceae)
Neocupressus lusitanica var. lindenii
(Cupressaceae)
Inga micheliana (Mimosaceae)
Ficus sp. (Moraceae)
Neocupressus lusitanica var. lindenii
Neocupressus lusitanica var. lindenii
Neocupressus lusitanica var. lindenii
Neocupressus lusitanica var. lindenii
Neocupressus lusitanica var. lindenii
Grevillea robusta (Proteaceae)
Ulmus mexicana (Ulmaceae)
Aegiphila valerioi (Verbanaceae)
Cecropia obtusifolia (Cecropiaceae)
Coccoloba escuintlensis
(Polygonaceae)
Ficus sp.
Ficus aurea (Moraceae)
Eucalyptus sp. (Myrtaceae)
Ocotea sinuata (Lauraceae)
Cornus disciflora (Cornaceae)
SF
NIC
NIC
BF
NIC
NIC
NIC
NIC
NIC
NIC
BF
BF
NIC
BF
BF
NIC
IC
NIC
BF
-
-
35
80
50
50
50
50
50
95
70
35
38
45
285
120
35
66
100
10
-
8
22
20
20
20
20
18
30
22
24
27
25
40
24
25
20
40
9
-
7.5
-
17
18
18
18
18
17
18
18
25
23
35
23
15.5
9
32
50
35
35
0
30
30
30
30
30
21
12
36
17
40
550
24
40
62
500
57
NESTING OF AZURE-RUMPED TANAGER
APPENDIX (Continuation).
Nest Year Locality Elevation
(m a.s.l.)
Nest tree* (family) Habitat DBH
(cm)+
Tree height
(m)
Nest height
(m)
Distance to
forest edge (m)
20
21
22
23
24
25
26
27
28
29
30
31
32
2008
2008
2008
2009
2009
2009
2009
2009
2009
2009
2009
2009
2009
Los Tarrales Reserve
Los Tarrales Reserve
San Jerónimo Miramar
Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
Los Tarrales Reserve
1780
1530
1400
930
1500
1510
1540
1850
1400
1370
1400
1400
1530
Sideroxylon portoricense
ssp. minutiflorum (Sapotaceae)
Ficus aurea
Acrocarpus fraxinifolius (Fabaceae)
Ficus crassiuscula (Moraceae)
Neocupressus lusitanica var. lindenii
Neocupressus lusitanica var. lindenii
Cedrela salvadorensis (Meliaceae)
Chiranthodendron pentadactylon
(Sterculiaceae)
Cedrela pacayana (Meliaceae)
Ulmus mexicana
Neocupressus lusitanica var. lindenii
Persea americana (Lauraceae)
Ficus aurea
BF
BF
IC
BF
NIC
NIC
BF
BF
BF
BF
OS
OS
BF
60
420
35
120
63
50
120
≈ 50
100
65
33
60
420
34
40
20
25 (50)*
25
18
25
20 (70)*
38
28
11.5
14
40
28
20
17
30
21
13
11
68
35
25
10.5
8
20
450
80
130
16
5
30
0
700
80
12
60
70
80
