104 THE WILSON BULLETIN x Vol. 113, No. 1, March 2001 Wilson Bull., 113(1), 2001, pp. 104±108 Aspects of the Breeding Biology of the Crested Gallito Eduardo T. Mezquida1,2 ABSTRACT.ÐI studied the breeding biology of the Crested Gallito (Rhinocrypta lanceolata) and Crested Gallito (Rhinocrypta lanceolata) in the Re- the Sandy Gallito (Teledromas fuscus; Naros- Ä serve of NacunÄaÂn (western Argentina) from September ky and Yzurieta 1987). The Crested Gallito is 1995 to January 1999. The laying period extended from mid-September to late January, a month longer a relatively large bird with a bushy crest than previous reports from Argentina. The closed nest (FjeldsaÇ and Krabbe 1990, Ridgely and Tudor was globular with a side entrance and was made pri- 1994) and is resident in the Reserve of NÄ a- marily of grasses. In NÄ acunÄaÂn, this species preferred cunÄaÂn (Mendoza Province, Argentina; Marone to nest in atamisque (Capparis atamisquea). Atam- 1992). The breeding biology of this species is isques selected for nesting were 1.6±3.5 m in height, poorly known and only limited characteristics and nests were 1.0±2.1 m above the ground. Mean clutch size (2.2 eggs) did not show a year or a seasonal of the nests and eggs have been described variation. Mean egg size and mass were less than those (Fraga and Narosky 1985). Other important reported previously. The incubation period lasted 16± life history traits, such as the duration of in- 17 d and the nestling period 14±15 d. Eggs hatched cubation and nestling stages, have not been asynchronously. No cases of brood parasitism by published previously. This note presents data Shiny Cowbird (Molothrus bonariensis) were ob- about breeding biology parameters of the served. Received 31 July 2000, accepted 3 February Crested Gallito, including phenology of clutch 2001. initiation, nest, nest sites, eggs, laying inter- val, clutch size, length of incubation and nes- tling periods, and development of nestlings, in The Family Rhinocryptidae includes 35 an arid area of Argentina. recognized species found primarily in south- ern South America (FjeldsaÇ and Krabbe METHODS 1990). These birds are almost entirely insec- I studied the Crested Gallito in the Reserve of NÄ a- tivorous, predominantly terrestrial, and have cunÄaÂn (348 039 S, 678 549 W; 12,282 ha), Mendoza secretive habits (Goodall et al. 1957, Ridgely Province, Argentina, from 1995±1999 during the and Tudor 1994). Most nest in holes, crevices, breeding seasons (September through February). The reserve (mean elevation 5 540 m) is in the central and burrows, but some species (of the genera portion of the Monte Desert Biome, a narrow latitu- Eugralla and Rhinocrypta) build closed nests dinal strip in western Argentina, at the foot of the An- in trees and shrubs (Fraga and Narosky 1985). des. The predominant habitat in the reserve is an open Two species of Rhinocryptidae inhabit the Prosopis ¯exuosa woodland with abundant shrub plains of Mendoza Province, Argentina: the (mainly Larrea divaricata, Capparis atamisquea, Ly- cium spp.) and grass cover (e.g., genera Pappophorum, Trichloris, Sporobolus, Digitaria). NÄ acunÄaÂn's climate 1 Ecodes, UF&EV, IADIZA, Casilla de Correo 507, is dry and temperate with cold winters. Mean annual 5500 Mendoza, Argentina. rainfall is 331 mm, although it is highly variable from 2 Current address: P. Alameda de Osuna 74 1 C, year to year, with most (78%) precipitation occurring 28042 Madrid, Spain; E-mail: ricardo.mezquida@adi. in spring and summer (October through March; Ma- uam.es rone 1992, Mezquida 2000). SHORT COMMUNICATIONS 105 FIG. 1. Initiation of egg laying by the Crested Gallito, NÄ acunÄaÂn, Argentina, during four breeding seasons (1995±1999). I began searching for nests in late September. I mea- tain the area covered by each species. Mean crown sured nest dimensions (external and internal diameter area of the plant species used by Crested Gallitos for from the entrance to the back, external height, and en- nesting was calculated from a random sample. I estab- trance diameter) for some nests, although external di- lished random transects and chose the closest plant at ameter and external height were recorded for only a 25-m intervals. For each plant I measured the maxi- small sample of nests. To characterize nest sites I re- mum diameter of the crown and its perpendicular to corded plant species, plant height, crown diameter of calculate the area of the ellipse formed by both di- the plant, height of the nest's entrance above ground, ameters. Sample size was .100 plants for all species, distance from nest's entrance to the top of the plant except Prosopis ¯exuosa where only 25 plants were directly above the nest, a periphery index (visually cal- measured. culated as the ratio of trunk to nest distance divided Frequency of nest placement among available plants by the canopy radius at nest height; Lazo and Ana- was compared using chi-square analysis. To analyze if baloÂn 1991), and number and diameter of branches nest height differed among nesting plants I used uni- supporting the nest. I visited nests every 1±3 d to mon- variate ANOVA. I compared clutch size among years itor status until failure or ¯edging. I numbered each and within the breeding season with Kruskal-Wallis egg with waterproof ink and measured its maximum and Mann-Whitney nonparametric tests. length and breadth to the nearest 0.1 mm. Egg and nestling mass were measured to the nearest 0.1 g. RESULTS Clutch initiation date was calculated either by direct observation or by extrapolation from known hatching I located 60 Crested Gallito nests during the or ¯edging dates. four breeding seasons. In 18 of these nests I compared the selection of plant species used for breeding activity was not observed, but I mea- nesting with the frequency distribution of the various sured characteristics of the nest site. The lay- species in the habitat to determine if nest plants were used in proportion to their availability. To estimate the ing period spanned from mid-September to density of each plant species I calculated the area cov- late January (Fig. 1). The earliest date of ered by each species on 60 random circular plots (10- clutch initiation was 15 September (in 1997) m radius) and divided it by the mean crown area of and the latest was 2 October (in 1998). The each plant species. I located 60 random plots and de- date of the last egg of the last nest found in termined percent cover of the various plant species us- NÄ acunÄaÂn was 31 January (range: 22 Novem- ing radial transects. Radial transects consisted of two perpendicular 20-m lines, with one line oriented north ber±31 January, during four breeding sea- and south. I selected 40 random points, with a mini- sons). mum distance 10 cm between consecutive points, The closed nest was globular with a side along each transect. The total number of points mea- entrance (mean external diameter 6 SE: 17.5 sured at each plot was 80. At each sampling point, I 6 1.3 cm, n 5 5; internal diameter: 12.0 6 inserted a thin aluminum rod vertically into the vege- 0.2 cm, n 5 39; external height: 14.8 6 0.5 tation and recorded the species of plant that touched cm, n 4; and entrance diameter: 6.9 0.2 the rod. Horizontal cover of each species was calcu- 5 6 lated as the number of points with hits of that plant cm, n 5 34). Nests were mainly leaves and divided by 80. These values were multiplied by the tillers of grasses of the genera Sporobolus, area of the circle formed by the radial transects to ob- Pappophorum, and Setaria, with some sticks 106 THE WILSON BULLETIN x Vol. 113, No. 1, March 2001 TABLE 1. Crested Gallito nest site characteristics, NÄ acunÄaÂn, Argentina, 1995±1999. Values are means 6 SE (n). Plant species Characteristics Prosopis ¯exuosa Geoffroea decorticans Capparis atamisquea Plant height (m) 5.5 6 0.3 (4) 3.2 6 0.2 (6) 2.3 6 0.1 (42) Crown diameter (m) Ð 2.4 6 0.4 (6) 3.4 6 0.1 (37) Nest height (m) 1.8 6 0.3 (4) 1.7 6 0.2 (7) 1.4 6 0.0 (43) Nest to canopy distance (m) 3.0 6 0.3 (3) 1.0 6 0.2 (6) 0.6 6 0.0 (37) Periphery index 0.5 6 0.2 (3) 0.4 6 0.1 (6) 0.5 6 0.0 (42) Number of branches supporting the nest Ð 4.5 6 0.5 (2) 5.1 6 0.2 (17) Diameter of branches supporting the nest (nm) 15.0 6 5.0 (2) 16.2 6 5.9 (9) 12.2 6 1.7 (77) of small shrubs (e.g., Lycium spp.) or trees in 1996; 2.3 6 0.1, n 5 12 in 1997; and 2.0 (e.g., chanÄar, Geoffroea decorticans), and thin 6 0.3, n 5 6 in 1998; Kruskal-Wallis test, H3 vegetal ®bers and petioles of Prosopis ¯exu- 5 1.3, P . 0.7). Within the breeding season, osa towards the inner part. The inner part of the size of clutches initiated before the mean the nest was lined with hair, wool, or the cot- laying date (2.0 6 0.1, n 5 24) did not differ ton-like appendices of Digitaria californica signi®cantly from those initiated after the seeds. mean laying date (2.4 6 0.1, n 5 13; Mann- Crested Gallito nests (n 5 60) were built in Whitney U-test, U 5 105.0, P .