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Eisermann K.,PROEVAL RAXMU Bird Monitoring Program | Arbeiter S.,PROEVAL RAXMU Bird Monitoring Program | Arbeiter S.,Eberswalde University Of Applied Sciences | Lopez G.,Los Tarrales Reserve | And 5 more authors.
Ornitologia Neotropical | Year: 2011

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 ranging 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 broadleaf 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 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 calculating 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. © The Neotropical Ornithological Society.

Eisermann K.,PROEVAL RAXMU Bird Monitoring Program | Howell S.N.G.,P.O. Box 423
Journal of Raptor Research | Year: 2011

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 ± 0.5 notes/sec (n = 49 call series of six individuals), significantly higher than in Mountain Pygmy-Owls (1.9 ± 0.3 notes/sec, n = 34 call series of eight individuals). This new evidence of vocal differences supports modern taxonomic separation of both taxa. © 2011 The Raptor Research Foundation, Inc.

Eisermann K.,PROEVAL RAXMU Bird Monitoring Program | Arbeiter S.,PROEVAL RAXMU Bird Monitoring Program | Arbeiter S.,Eberswalde University Of Applied Sciences | Lopez G.,Los Tarrales Reserve | And 2 more authors.
Bird Conservation International | Year: 2011

The Azure-rumped Tanager Tangara cabanisi is a globally threatened species restricted to the Pacific slope mountains of western Guatemala and Chiapas, Mexico. We studied the habitat use of this tanager on the southern slope of Atitlán volcano, department Suchitepéquez, Guatemala, applying distance sampling along transects in humid broadleaf forest and coffee plantations. The tanager was recorded in both habitat types, but encounter rates were significantly greater in broadleaf forest. The estimated density of tanagers in forest at 1,400-1,900 m was 33-93 birds km -2. Tanagers were recorded mainly in the upper vegetation strata of forest and shade coffee plantations. In coffee plantations tanagers used mainly tall solitary trees or the canopy of shade trees, which were dominated by Inga spp. The number of observations of feeding tanagers in Ficus aurea (Moraceae) indicated a high importance of this food source. The density of F. aurea trees and the encounter rate of tanagers were positively correlated. From 1987 to 2009 tanagers have been recorded at nine topographic units and a total of 16 sites in Guatemala, in the departments of San Marcos, Quetzaltenango, Sololá, Suchitepéquez, and Chimaltenango. We analysed the available habitat for tanagers in the potential area of distribution (1,170 km 2), ranging from 900 to 1,900 m altitude and from the Mexican border in the West to the municipality of Pochuta in the East. Broadleaf forest covers 250 km 2 or 21% of the potential area of distribution, and coffee plantations cover 800 km 2 or 68%. Assuming that population density in prime habitat throughout the potential distribution range is similar to our study area at Atitlán volcano, total tanager population in Guatemala is estimated to be 8,250-23,250 birds. Our findings support the maintenance of the IUCN Red List status of Endangered EN B1a+b(ii,iii,v). To enhance the available habitat for Azure-rumped Tanager, we propose alterations in the shade management of coffee plantations, supported by incentives and certification programmes. © 2011 BirdLife International.

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