NEST, EGGS, AND PARENTAL CARE OF THE PUNA TAPACULO (SCYTALOPUS SIMONSI)

Transcription

1 The Wilson Journal of Ornithology 120(3): , 2008 NEST, EGGS, AND PARENTAL CARE OF THE PUNA TAPACULO (SCYTALOPUS SIMONSI) PETER A. HOSNER 1,3 AND NOEMÍ E. HUANCA 2 ABSTRACT. We describe the nest and eggs of the Puna Tapaculo (Scytalopus simonsi) from Bolivia, and include observations of nest building, incubation, and parental care. The nest is similar to several other described nests in the genus in construction and placement: a domed cup nest of grasses in an excavated burrow in a vertical bank. Both male and female constructed the nest, brooded, and provisioned the young, typical of Scytalopus and tracheophone suboscines. This is only the second described Scytalopus nest constructed of grasses, probably an adaptation to its drier habitat near and above treeline. The growing body of Scytalopus nest descriptions suggests they do not exhibit generic level stereotyped nest structure and placement, unlike other tracheophone suboscines, which show strong phylogenetic signal in nest architecture. Received 1 September Accepted 26 January Scytalopus is among the most diverse and abundant groups of Andean birds, yet their breeding biology is poorly understood. Nests of 15 of the 41 (Gill and Wright 2006, Remsen et al. 2008) currently recognized species of Scytalopus have been described, all of which share similarities but differ somewhat in placement or structure. The nest site is usually some form of natural crevice or cavity (Skutch 1972, Hilty and Brown 1986, De Santo et al. 2002, Acros-Torres and Solano-Ugalde 2007), excavated burrow in an earthen bank (Johnson and Goodall 1965, Stiles 1979, Young and Zuchowski 2003, Decker et al. 2007, Pulgarin-R 2007), cavity in a rotten log (Greeney and Gelis 2005), or hidden among dense foliage, roots, trunks, fallen leaves, and moss (Rosenberg 1986, Sick 1993, Christian 2001). Nest architecture in Scytalopus approaches the entire range of variation of all the rhinocryptids (Krabbe and Schulenberg 2003) and nests usually are domed or globular in shape with a top or side entrance; only nests of White-browed Tapaculo (S. superciliaris) (Stiles 1979) and Long-tailed Tapaculo (S. micropterus) (Greeney et al. 2005) have been found with an open cup. Nests are constructed from a variety of plant material including mosses, lichens, rootlets, leaves, small sticks, and are at times lined with grasses, hair, or feathers (Krabbe and Schulenberg 2003). 1 Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA. 2 Asociacíon Armonia, Santa Cruz de la Sierra, Santa Cruz, Bolivia. 3 Corresponding author; hosner@ku.edu 473 Field observations of Scytalopus during the breeding period are extremely limited. Males lack a brood patch (Krabbe and Schulenberg 2003), but incubation has been reported by both males and females (Young and Zuchowski 2003, Decker et al. 2007), as has brooding (Greeney et al. 2005). The incubation period has been reported to be from 15 (Sick 1993) to 19 days (DeSanto et al. 2002); the only recorded fledging period is 11 days (DeSanto et al. 2002). Both parents actively provision the chicks with small arthropods (Christian 2001, Young and Zuckowski 2003, Greeney and Gelis 2005, Greeney and Rombough 2005, Greeney et al. 2005). Nothing is recorded on nest building or post fledging care (Krabbe and Schulenberg 2003). The Puna Tapaculo (Scytalopus simonsi) occurs at high elevations (2,000 4,500 m) in Puna grassland, ravines with shrubby vegetation, Polylepis woodland, and elfin forest edge from Departamento Cuzco, Peru south to Departamento Santa Cruz, Bolivia (Hennessey et al. 2003, Krabbe and Schulenberg 2003). Once considered conspecific with Magellanic Tapaculo (S. magellanicus) (i.e., Zimmer 1939), differences in song, distribution, and morphology have split this complex into 11 recognized species with further taxonomic revisions likely (Remsen et al. 2008). The objectives of this paper are to describe the nest, eggs, and parental care in S. simonsi, and discuss trends in Scytalopus breeding behavior. OBSERVATIONS On 16 December 2006 near the community of Palcapampa (17 20 S, W; 3,550

2 474 THE WILSON JOURNAL OF ORNITHOLOGY Vol. 120, No. 3, September 2008 FIG. 1. Schematic of nest burrow of Puna Tapaculo showing the false and nest chambers. Photograph of entrance hole (inset). m), Departamento Cochabamba, Bolivia, we observed a Scytalopus simonsi hopping across a footpath carrying grasses. The bird (presumed to be a female as it lacked a white postocular line) re-crossed the footpath after 30 sec and hopped up a steep bank, disappearing into one of about nine burrows. When we retuned to the site on 17 December 2006, a S. simonisi was peering from the entrance of the nest hole (presumed to be the male of the pair based on the distinctive short whitish post-ocular stripe). The bird exited, dropped to the ground and crept away. The bank was 2.5 m tall and was constructed as a terrace between two small potato fields. The bank was almost vertical, sloping gradually to horizontal as it met the lower field. The nest hole was in plain view, 20 cm below the top of the bank, which was covered with grasses and other herbaceous vegetation. There was a small (15 m wide, 3 m deep) ravine 20 m from the nest site with Alnus acuminata, Polylepis besserii, and other native shrubs including Gynoxis, Baccharis, Ribes, and Berberis, and Festuca and Cortaderia grasses, a more typical habitat of the species. The male was heard singing there infrequently (a few songs per hour) during investigation of the nest. The entrance hole (Fig. 1) measured 9 4 cm, the only oval hole among many circular holes of various sizes in the bank. The burrow (Fig. 1) went straight into the bank 18 cm, tapering slightly before turning sharply 80 to the right, narrowing to cm, and continuing another 16 cm before opening into two chambers: one empty to the left, and one to the right which contained the nest. A few rootlets from herbaceous vegetation emerged from the ceiling of the burrow. The nest was in an FIG. 2. Nest cup of Puna Tapaculo after extraction from the burrow; the dome could not be extracted for photographs. The two eggs (inset). area replete with rodent burrows (9 other holes within a few meters of the nest). The entrance to the nest chamber was oval, measuring 10 8 cm, the nest chamber itself was almost spherical at cm. The sides and ceiling of the chamber were lined with 4 cm of loosely woven dried Cortaderia grasses that formed a dome over the nest. The nest cup (Fig. 2) was 12 cm in diameter and 10 cm in height, filling the lower twothirds of the nest chamber. The walls and bottom of the cup were lined with 3.5 cm of much more tightly woven grasses than the loose dome. Five blades of Cortaderia grass taken at random from the nest cup measured 5, 7, 8, 12, and 17 cm in length; all grasses were about 0.5 mm in width. The cup had an inside diameter of 5 cm and inside depth of 6.5 cm. The lining of the interior of the cup was of much smaller, finer grasses than the rest of the nest and included a few long black horse hairs, several species of bird feathers including domestic chicken (Gallus gallus), and a single piece of moss. The nest was clean and devoid of droppings upon extraction. The nest contained two eggs that were cold on 17 December 2007, although the male was in attendance. The eggs were white, the eggshells seemed thin and had a transparent quality; the air sac at the large end of the egg was easily visible. Eight sets of transparent parallel lines 2 mm apart went half the length of the eggs, converging at the small tip. Egg #1 measured mm, weighing 3.9 g; egg #2 measured mm and weighed 3.8 g. The male continued to bring stems of grass to the nest after the eggs were replaced. The eggs hatched by 4 January and the

3 Hosner and Huanca NESTING OF PUNA TAPACULO 475 chicks were estimated to be 2 days of age, weighing 4.5 and 4.9 g with nare to tip of bill measurements of 3.8 and 3.9 mm. Assuming incubation began on 18 December 2007, the day after the two eggs were found to be cold, the incubation period would have been 16 days. The chicks retained the egg tooth, had eyes closed, and were partially covered with long, thick mouse gray natal down on the crown, back, wings, and legs. After the chicks were returned to the nest, the female brooded for 27 min. The male arrived with food and the pair switched with the male staying to brood. The pair alternated brooding and foraging 33% of the time observed. The brooding bird would stay in the nest until the other returned with food, then exited allowing the provisioning bird to enter, feed the chicks, and brood the nestlings. The female made six foraging bouts and the male four from 1500 to 1630 hrs CST. The food brought by the adults appeared to be a mix of 50% small ( 10 mm) insect larvae and 50% ( 5 10 mm) small adult insects with one small white moth ( 10 mm). The female spent 34 min of the 1.5 hrs brooding and at dusk spent the night brooding in the nest. The male spent 16 min brooding during this period and roosted at night in nearby shrubs. The chicks weighed 5.7 and 6.2 g on 6 January 2007, and provisioning behavior by the adults was similar although they spent little time brooding, and exited the nest directly after feeding rather than waiting for the arrival of their mate. The female made seven foraging bouts, the male four in 1.15 hrs of observation. Adults entered the nest hole three times but were not identified to gender. Begging calls of the chicks were recorded (ML #132524) by placing a microphone inside the nest for 30 min during active feeding. The chicks called (soft high pitch peeping) almost continuously in the presence and absence of adults. Provisioning behavior was similar in 30 min of observation on 7 January 2007 and both adults were observed removing fecal sacs from the nest for the first time. The chicks were covered in pin feathers on 14 January 2007, although their eyes were still closed and they retained some natal plumes on the crown and back. The majority of the feathers on the back had lost their pins and were brown with thick black barring typical of all juvenile Scytalopus. The chicks weighed 18.1 and 19.8 g, had nare to tip of bill measurements of 6.2 and 6.3 mm, and tarsi of 19.7 and 20.4 mm. The nest was empty on 6 February and was removed from the cavity. The fledging period was 12 days and, given the stage of development at 12 days, a fledging period of days seems reasonable. DISCUSSION Given the identification issues and taxonomic changes in this genus (i.e., Krabbe and Schulenberg 1997), a recording of the male at the nest was deposited at the Macaulay Library at Cornell University (ML #132525). Young and Zuchowski (2003) erroneously cited a nest of S. simonsi found by T. S. Schulenberg in Puno, Peru (Rosenberg 1986). This nest correctly pertains to Diademed Tapaculo (S. schulenbergi) (Krabbe and Schulenberg 2003; T. S. Schulenberg, pers. comm.). The domed nest was similar in structure to other Scytalopus nests; however, use of bunch grasses as construction material has been previously reported only in S. superciliaris (Stiles 1979). Use of bunch grasses is probably an adaptation for living in areas above treeline where it is one of the only nesting materials available. Mosses were available at the site, although in much less quantity than the extremely humid subtropical and temperate mossy forests where the majority of the Scytalopus nests have been described. This pair of S. simonsi also used a longer tunnel than previously described for nests of the genus; however, the growing number of Scytalopus nest descriptions suggests the genus is extremely variable and opportunistic in selecting a nest site. They apparently use a variety of structures for nest sites and, perhaps, vary nest architecture based upon the individual nest site (Greeney and Gelis 2005, Greeney 2008), rather than stereotyped nest architecture with a genetic basis (i.e., Zyskowski and Prum 1999, Zimmer and Isler 2003, Brumfield et al. 2007) seen in other tracheophone groups. It appears likely the nest burrow was modified from an old rodent excavation and that rodents, rather than Scytalopus, constructed the false chamber and nest chambers. Alternatively, the shape of the entrance resembled the burrow of Bar-winged Cinclodes (Cinclodes

4 476 THE WILSON JOURNAL OF ORNITHOLOGY Vol. 120, No. 3, September 2008 fuscus) and it could have been a re-used burrow of that species. Recently, Greeney (2008) described the first unambiguously re-used nest by a Scytalopus, the Long-tailed Tapaculo, which had taken over a nest built and used to raise three broods by a pair of Spotted Barbtails, (Premnoplex brunnescens). Parental care of the chicks was typical for the genus (Greeney and Gelis 2005, Greeney and Rombough 2005, Greeney et al. 2005) with both parents contributing to virtually all activities. The sexual dimorphism in S. simonsi allowed for our novel observations that males also contribute to nest building, and that while the male actively contributed to feeding and brooding, it provisioned slightly less frequently and spent less time brooding than the female. The used nest devoid of fecal sacs from the chicks suggests that, like in other nests (Greeney and Gelis 2005, Greeney and Rombough 2005), S. simonsi chicks may excrete outside of the nest and the parents keep the nest extraordinarily clean. The appearance of the chicks and unique natal down were typical of Scytalopus (Greeney and Gelis 2005). However, the soft peeping calls of the chicks differed strongly from previous descriptions (Greeney and Gelis 2005) that Scytalopus chick vocalizations were loud and insect or woodpecker-like. Whether this is due to the young age of the S. simonsi chicks or interspecific differences is unknown. Incubation in S. simonsi appears much longer than that of magellanicus (DeSanto et al. 2002), but exact dates of laying and hatch are unknown. Little is known about the post-fledgling care of Scytalopus and we were unable to observe the birds post fledging. PAH frequently observed a pair of S. parkeri at Reserva Tapichalaca in Loja, Ecuador accompanying and provisioning a single fledgling in the same territory for 3 weeks from mid October through early November This suggests a long period of post-fledging care by adults in the group, much as in related tracheophone families (Zimmer and Isler 2003). Many aspects of Scytalopus breeding behavior (i.e., shared nest building, shared incubation although only the female incubates at night, shared provisioning of young, extended parental care after fledging, and low rates of nest success) appear similar to the other tracheophones. We hypothesize that Scytalopus are also similar to tracheophones in their monogamy, extended pair bonds, and other aspects of breeding biology yet to be studied or observed in this fascinating group. ACKNOWLEDGMENTS We thank the American Bird Conservancy for financing the study on Cochabamba Mountain Finch (Compospiza garleppi) during which we made these observations. We also thank Asociación Civil Armonía/BirdLife International and the communnities of Palcapampa and Portrero for allowing access to the study areas and providing support. The Macaulay Library at Cornell University loaned recording equipment. The Herbario Nacional Martín Cárdenas assisted in plant identification. A. B. Hennessey, S. K. Herzog, Luis Llanos, Felix Huanca, Israel Huanca, and Josias Huanca assisted with logistics and fieldwork. M. B. Robbins provided comments that improved the manuscript. LITERATURE CITED ACROS-TORRES, A. AND A. SOLANO-UGALDE First description of the nest, nest site, eggs, and nestlings of Narino Tapaculo (Scytalopus vicinior). Ornitologia Neotropical 18: BRUMFIELD, R. T., J. G. TELLO, Z.A.CHEVIRON, M.D. CARLING, N. CROCHET, AND K. V. ROSENBERG Phylogenetic conservation and antiquity of a tropical specialization: army-ant following in the typical antbirds (Thamnophilidae). Molecular Phylogenetics and Evolution 45:1 13. CHRISTIAN, D. G Nests and nesting behavior of some little known Panamanian birds. Ornitología Neotropical 12: DECKER, K. L., A. M. NIKLISON, AND T. E. MARTIN First description of the nest, eggs, and breeding behavior of the Merida Tapaculo (Scytalopus meridanus). Wilson Journal of Ornithology 119: DE SANTO, T. L., M. F. WILLSON, K. E. SIEVING, AND J. J. ARMESTO Nesting biology of tapaculos (Rhinocryptidae) in fragmented south-temperate rainforests of Chile. Condor 104: GILL, F. AND M. WRIGHT Birds of the world. Recommended English names. Princeton University Press, Princeton, New Jersey, USA and Oxford, United Kingdom. GREENEY, H. F Additions to our understanding of Scytalopus tapaculos reproductive biology. Ornitología Neotropical 19: In press. GREENEY, H.F.AND R. A. GELIS The nests and nestlings of the Long-tailed Tapaculo (Scytalopus micropterus) in Ecuador. Ornitología Colombiana 3: GREENEY, H.F. AND C. J. F. ROMBOUGH First nest of the Chusquea Tapaculo (Scytalopus parkeri) in southern Ecuador. Ornitología Neotropical 16: GREENEY, H. F., A. D. L. BUECKER, AND N. HARBERS.

5 Hosner and Huanca NESTING OF PUNA TAPACULO Parental care of the Blackish Tapaculo (Scytalopus latrans) in northeastern Ecuador. Ornitología Neotropical 16: HENNESSEY, A. B., S. K. HERZOG, AND F. SAGOT Lista anotada de las Aves de Bolivia. Quinta Edición. Asociación Armonia/Birdlife International, Santa Cruz de la Sierra, Bolivia. HILTY, S.L.AND W. L. BROWN A guide to the birds of Colombia. Princeton University Press, Princeton, New Jersey, USA. JOHNSON, A. W. AND J. D. GOODALL The birds of Chile and adjacent regions of Argentina, Bolivia, and Peru. Volume. 2. Platt Establecimientos Graficos S.A., Buenos Aires, Argentina. KRABBE, N. AND T. S. SCHULENBERG Species limits and natural history of Scytalopus tapaculos (Rhinocryptidae), with descriptions of the Ecuadorian taxa, including three new species. Ornithological Monographs 48: KRABBE, N. AND T. S. SCHULENBERG Family Rhinocryptidae (tapaculos). Pages in Handbook of the birds of the world. Volume 8. Broadbills to tapaculos (J. Del Hoyo, A. Elliot, and D. Christie, Editors). Lynx Edicions, Barcelona, Spain. PULGARIN-R, P. C The nest and eggs of Spillmann s Tapaculo (Scytalopus spillmanni). Ornitología Colombiana 5: REMSEN JR., J. V., A. JARAMILLO, M. A. NORES, M. B. ROBBINS, T.S.SCHULENBERG, F.G.STILES, J.M.C. DA SILVA, D.F.STOTZ, AND K. J. ZIMMER A classification of the bird species of South America. American Ornithologists Union. museum.lsu.edu/ Remsen/SACCBaseline.html. ROSENBERG, G The nest of the Rusty-belted Tapaculo (Liosceles thoracicus). Condor 88:98. SICK, H Birds in Brazil: a natural history. Princeton University Press, Princeton, New Jersey, USA. SKUTCH, A Studies of tropical American birds. Publications of the Nuttall Omithological Club Number 10. STILES, E The nest and eggs of the Whitebrowed Tapaculo (Scytalopus superciliaris). Condor 81:208. YOUNG, B. E. AND W. ZUCHOWSKI First description of the nest of the Silvery-fronted Tapaculo (Scytalopus argentifrons). Wilson Bulletin 115: ZIMMER, J. T Studies of Peruvian birds 32. The genus Scytalopus. American Museum Novitates. 1044:l 18. ZIMMER, K. J. AND M. J. ISLER Family Thamnophilidae (typical antbirds). Pages in Handbook of the birds of the world. Volume 8. Broadbills to tapaculos (J. Del Hoyo, A. Elliot, and D. Christie, Editors). Lynx Edicions, Barcelona, Spain. ZYSKOWSKI, K. AND R. O. PRUM Phylogenetic analysis of the nest architecture of neotropical ovenbirds (Furnariidae). Auk 116: