Revista Chilena de Historia Natural 70: 221-224, 1997 Notes on the breeding biology and population density of the Tucuman mountain- ( baeri; Aves: Emberizidae) in Argentina, with description of nest and eggs

Notas sobre la biologfa reproductiva y densidad de poblaciones de la monterita serrana (Poospiza baeri; Aves: Emberizidae) en Argentina, con descripci6n del nido y puesta

SALVADOR J. PERIS

Departamento de Biologia -Zoologia, Facultad de Biologfa, Universidad de Salamanca, 37071 Salamanca, Espafia. E-mail: [email protected]

ABSTRACT

Line transect census work carried along ravines of the Aconquija mountain (NW Argentina) among 1989 to 1993, gave a breeding density of the Tucuman mountain-finch between 0.02-0.03 per km. Highest post-breeding density (0.25 birds/km) was found between 2,600-3, I 00 m.a.s.l. Breeding of the species occurs from December to March with observed fledglings in April. Two nest and eggs found near El lnfiernillo mountain-pass (Tucuman) are described. According to measurements taken on museum specimens, mean wing lenght and red breast patch is statistically significant larger in males than in females.

Key words: Tucuman Mountain-Finch, Breeding, Population.

RESUMEN

Censos basados en transectos y llevados a cabo entre 1989-1993, en barrancales de la Sierra del Aconquija (NO Argentina) ofrecen una densidad poblacional de 0,02-0,03 individuos de Monterita Serrana por km2 Una mayor densidad post- reproductiva de 0,25 aves/km fue encontrada entre 2.600-3.100 rn.s.n.rn .. La reproducci6n tiene lugar entre diciernbre a marzo, observandose aves j6venes en abril. Se describen dos nidos de la especie encontrados cerea del puerto de montafia dellnfiernillo (Tucuman). Basados en medidas tomadas sobre especimenes de museo, la longitud media del ala y la mancha rojiza del pecho es estadisticamente significativo mayor en Ios individuos rnachos.

Palabras clave: Monterita Serrana, Reproducci6n, Poblaciones.

INTRODUCTION there is an urgent need for know the dis- tributional status and ecological require- The Tucuman Mountain-finch (Poospiza ments of the (Collar et. al 1992). The baeri, Oustalet 1904), is considered a full species is restricted to a very small area species of the genus Compsospiza (e.g., and habitat in north western Argentina Meyer de Schauensee 1966, Narosky & and very little is known about its ecolo- Yzurieta 1987, Navas & Bo 1991, Nores gy, including estimate of total popula- 1991 ), or treated as a subspecies of Poos- tion, because of lack of studies probably piza garleppi (Bond 1951, Ridgely & Tu- due to inaccessibility of its habitat. The dor 1989, Fjeldsa, 1992, Fje1dsa & Krab- aim of this paper is to present new infor- be 1990). In any case, the Tucuman mation on the biology of this rare spe- Mountain-finch is globally considered a cies, obtained in the course of a more ge- vulnerable/rare threatened species and neral study of the avifauna of the area.

(Received 15 December 1995; accepted 26 December 1996; managed by Guillermo Riveros) 222 PER IS

MATERIAL AND METHODS son (December-March) and between censu- ses, time was spent looking for nests of sie- Field work was carried out in the Aconqui- rra- (Phrygilus spp.) and during the- ja-Calchaqui mountain area, composed of se searches we found two nests of the two parallel Andean ranges between 27° Tucuman Mountain-finch. 20'S-65° 48' W to 26° 43' S-65° 45' W in In addition to our field observations, we Tucuman province (NW Argentina). The examined a total of 24 museum specimens east slope of the range above 2.200 m.a.s.l. ( 14 in the Museum Miguel Lillo of San Mi- is covered by a large and relatively uniform guel de Tucuman and 10 at the American open grassland, the dominant genus being Museum of Natural History of New York). Festuca and Stipa (Gramineae). The land- Based on these specimens, differences be- scape is only broken by steep, bushy ravi- tween sexes were analyzed according to nes and some small woodland patches of wing length (flattened wing; Svensson Mountain Alder (Alnus acuminata) and 1992), length of bill and extension of the "Queiioa" trees (Polylepis australis). In the orange-tawny breast-band. western part of the range, the habitat is an arid prepuna montane scrub with big cacti (Echinopsis paroaria) and, at a lower alti- RESULTS AND DISCUSSION tudes, "Algarrobo" trees (Prosopis spp.). For a more detailed description of the gen- Population and movements eral area see Meyer & Weyrauch (1966), Vervoorst (1982) and Peris & Alabarce The species has only been observed along (1991 ). Previous bird data for the region the humid eastern slope of the range. In the have been published by Olrog ( 1949) and breeding season the Tucuman mountain- Handford (1983). finch appears above 2.500 m. Breeding Bird censuses work was carried out in birds have a very low density of 0.02 indi- the study area in order to sample seasonal viduals per square-km of prospected bushy bird distribution and populations. Methodo- ravine and they are more abundant up abo- logy used was line transect counts with ve 2.800 m (0.03 individuals per square sampling units of 20 minutes (Hirvinen & km). In the post-breeding season (late Mar- Vaisanen 1977, Telleria 1978), which rep- ch to April) with ravines and grassland resent about 700-1000 m covered and were pooled together, it was possible to detect an made to divide small sample sections, who- increase to 0.25 birds per square km be- se habitats could be measured. tween 2.600-3.100 m.a.s.I. (Peris & Alabar- All the birds observed at 25 m ce 1991) due to dispersal of fledglings and from the observer were counted (a main adults. Near winter (May-June), several in- belt 50 m wide), and also those observed dividuals were observed on river side scrub more than 25 from the observer as a sup- and willows (Salix spp.) bordering the Tafi plementary belt. All the surveys were made and Blanquito rivers, at about 0.5 and 2 by the same observer and the data have not kms from the town of Taff del Valle. been transformed. Since the validity of the People in this village reported the presence method under Andean conditions is not of this species in bushes of private gardens known, there may be some inherent bias; during July and August, and they stated for example it is more useful in determi- that the species was more abundant during ning the number of birds with small territo- winters with heavy snowfall. According to ries than those with large ones and as no preliminary census data (Peris, unpub.), the data exists on species detectabilities, some Tucuman Mountain-Finch has a relative precautions are needed in order to explain abundance of only 0.1% of all the bird spe- the densities found here. A total of 220 km cies present in the area (birds of prey ex- (about 1.100 ha) were covered from March cluded) and together with the Plain-capped 1989 to February 1993. Censuses were Ground-tyrant (Muscisaxicola alpina) made throughout the year except in winter could be, at the present time, one of the (July-September). During the breeding sea- least common passerine species in the re- BREEDING OF TUCUMAN MOUNTAIN-FINCH 223 gion, although Hand ford ( 1983) reported earlier than the reported main breeding sea- both species as frequent. At the present son of January-March (Collar et al. 1992). time, we cannot confirm the low estimate In our study area, one fledgling with a pale of 180-200 total individuals given by Nores red breast patch, was seen in early April. in 1985 (in Collar et al. 1992) and in fact, Until now the species' nest and eggs the species has new reports from Calilegua were unknown, however I discovered two National Park and the "La Quesera" stream nests. (Yala valley), both localities in Jujuy prov- The first nest was found on the 22nd ince, the Sierra del Manchao (Catamarca) January 1993, had three warm eggs and it and the high grasslands of the Sierra de Ve- was protected by a thick Stipa spp. grass in lasco in La Rioja province (Chebez 1994, a gully at 2.500 m.a.s.l., near the road in Wege & Long 1995). All these observations the "Infiernillo" mountain pass. The eggs are far away from the Infiernillo report and were clear white and sparsely spotted and could indicate a larger breeding range for speckled with darker purplish-brown and the species than the reported elsewhere. A olive-brown. These markings were concen- last survey conducted in apropiate habitat trated at or around the larger end. The in Cachi and Cachiadentro as well as in the shape was typical of emberizine birds. Egg "Valle Encantado" (Salta province) during measurements were 20.7 x 15.6 mm., 20.9 the 1995 breeding season ended unsuccess- x 15.7 mm and 21.1 x 15.8 mm. The eggs ful to find the bird. were not put in water in order to test how Possible threats to the species could many days they had been incubated. Five come from new agricultural practices in days later, the eggs were all completely de- part of its original habitat. During colonial stroyed. Probably unusuall cold weather at times, the Taff slope supported overgrazing this time of the season, with snow and and fire in order to create new pastures, but heavy rain, could be responsible for the recent dramatic changes have occurred in loss, although we cannot discard predation. the area with the introduction of new crops The second nest was found on 4 Feb- such as Seed-potatoes (Solanum tubero- ruary 1993 near "Muiioz" peak (26° 41'S- sum) since 1986 and strawberries (Fragaria 650 45'W, 3150 masl). It was situated on vesca) since 1989. Also the percentage of the ground and protected in dense grass- cultivated land has increased and currently lands of Stipa and Festuca. The nest site covers about 20% of the region. This newly was 500 m from a scattered Polylepis aus- converted agricultural land is sprayed with tralis woodland. The nest contained one pesticides during the breeding season and nestling only a few hours old and one very we have observed heavy mortality in some pale blue (practically white) and finely bird species such as burrowing owls (Athe- spotted egg; markings were similar to those ne cunicularia), between 1-3 days after found in the first nest. No measurements spraying. If these agricultural practices are were taken and it is impossible to know if improved, they could be a serious threat in this egg was that of the Shiny Cowbird a range that is considered a hotspot for (Molothrus bonariensis), but this species threatened birds in the neotropics (Wege & uses to breed lower in alti-tude (2.500 m; Long 1995). own data). One adult of the Mountain- Finch was seen emitting alarm calls at less Breeding than 6 m from this nest. On 13 February, two adult birds were seen with grasshop- The presence of slightly enlarged gonads in pers (Acrididae) near the place where the December are mentioned by Fjeldsa & nest was supposed to be, but unfortunately, Krabbe (1990). This is confirmed by 3 wind and/or rain had removed the signal males deposited in the M. M. L., whose tes- stick and it was impossible to find the nest tes begin to enlarge between December to again. Probably the youngs could have left January in the Sierra de Ambata, another the nest, as has been observed in some oth- mountain range, located about I 00 km er finches of the area (e.g., band-tailed Si- south of our study area. This is a month erra-finch Prygilus alaudinus). 224 PER IS

Measurements of museum specimens CHEBEZ JC (1994) Los que se van. Albatros, Buenos Ai- res. COLLAR N J, L P GONZAGA, N KRABBE, A MADRO- A sample of adult males (n = 12) have a NO NIETO, G NARANJO, TA PARKER lli & DC mean wing length larger than the adult fe- WEGE ( 1992) Tucuman Mountain-Finch. In: Threatened Birds of the Americas: 846-848. ICBP- males (n = 9) (80. I ± 2.2 mm (s. e.) in males IUCN Red Data Book, Cambridge. and 78.2 + I. I in females), and this diffe- FJELDSA J & N KRABBE ( 1990) Birds of the High An- rence is statistically significant (t-test = des. Zoology Museum University of Copenhagen- Apollo Books, Svendborg. 2.279, p<0.05); no statistically significant FJELDSA J ( 1992) Biogeographic patterns and evolution differences were found in the tarsus length of the avifauna of relict high-altitude woodlands of (mean = I 3.3 ± 0.4 in both sexes). The red the . Steenstrupia 18: 9-62. JARVINEN 0 & RA V AISANEN (1977) Line transect breast patch in males (29. 7 mm) is also sig- method: a standar for field work. Polish Ecological nificantly wider (t-test = 2. I 2, p<0.05) than Studies 3:11-15. that of females (27. I mm). This last feature HANDFORD PT ( 1983) Breves notas sobre !as aves de Tafi, provincia de Tucuman. Neotr6pica 29: 97-105. could be a useful sexual identification tool MEYER DE SCHAUENSEE R ( 1966) The Species of for researchers and bird banders. Birds of South America with their Distribution. Livington Publishing Company, Narberth. MEYER T & WK WEYRAUCH (1966) Guia para dos ex- cursiones biol6gicas en la provincia de Tucuman. ACKNOWLEDGMENTS Miscelanea Fundaci6n Miguel Lillo 34: 239-243. NAVAS J. & N ABO (1991) Anotaciones taxon6micas sobre Emberizidae y Fringillidae de la Argentina I would like to thank T. Narosky, D. R. (Aves, Passeriformes). Revista del Museo de La Phillips, Lloyd Kiff and D. C. Wege for Plata XIV, 119-134. information on the species. Mrs. E. Alabar- NAROSKY T & D YZURIETA (1987) Guia para la identi- L.) ficaci6n de !as Aves de Argentina y Uruguay. ce (M. M. and Mary Lecroy (A. M. N. Vazquez Massini, Buenos Aires. H.) who allowed me to study the bird col- NO RES M ( 1991) Checklist of the Birds of Argentina. Pu- lection of their respective museums and S. blicaci6n N" 10 Centro Zoologia Aplicada. Univer- sidad Nacional de Cordoba, Argentina. Mosa for field accompaniment in Salta pro- OLROG Cl ( 1949) Breves notas sob re la avifauna del vince. J. Fjeldsa, M. Robbins, P. T. Han- Aconquija. Acta Zooi6gica Lilloana 7:139-159. dford and three anonymous referees sug- PERIS S & E ALABARCE (1991) La avifauna postreproductora de Ios pastizales de altura (Tafi gested modifications in a previous draft. del Valle, Sierra del Aconquija, Tucuman). Acta Partial financial support for the field work Zool6gica Lilloana XL 125-133. was from the Spanish MEC (Programa 2 SVENSSON L ( 1992) Identification Guide to European . Stockholm. and Programa de Movilidad de Profesora- RIDGEL Y R S & G TUDOR ( !989) The Birds of South do), as well as from the University of Sala- America. The Oscine Passerines. University of manca. Field work would have been impos- Texas Press. Austin. 814 pp. TELLER IA JL ( 1978) Introducci6n a Ios metodos de estu- sible without the hospitality of the dio de las comunidades nidificantes de aves. Chenaut-Soaje family. Ardeola 24: 19-65. VERVOOST F ( 1982) Noroeste. In "Conservaci6n de la vegetaci6n natural en la Republica Argentina 2". Simposio XVlll Jornadas Argentinas Botanica Serie LITERATURE CITED Conservacion Naturaleza, Tucuman: 9-24. WEGE DC & LONG AJ (1995) Key Areas for BOND J (1951) Notes on Peruvian Fringillidae. Threatened Birds in the Neotropics. BirdLife Proceedings Academy of Natural Science of International (BirdLife Conservation Series N° 5), Philadelphia I 03: 65-84. Cambridge. 311 pp.