The Wilson Journal of Ornithology 123(1):137–141, 2011 NESTING BIOLOGY, HOME RANGE, AND HABITAT USE OF THE BROWN WOOD RAIL (ARAMIDES WOLFI) IN NORTHWEST ECUADOR JORDAN KARUBIAN,1,4 LUIS CARRASCO,2 PATRICIO MENA,2 JORGE OLIVO,2 DOMINGO CABRERA,2 FERNANDO CASTILLO,2 RENATA DURA˜ ES,1 AND NORY EL KSABI3 ABSTRACT.—The Brown Wood Rail (Aramides wolfi) is a globally threatened, poorly known species endemic to the Choco´ rain forests of South America. We provide a first report on the species’ nesting biology, home range, and habitat use. Nests (n 5 16) were open cups ,2 m above ground and were more common in secondary forest than expected by chance. Median clutch size was four eggs, incubation lasted .19 days, the precocial young departed the nest within 24 hrs of hatching, and 66% of nests successfully produced young. At least two adults participated in parental care and pair bonds appear to be maintained year-round. The home range of an adult radio-tracked for 7 months was 13.5 ha in secondary and selectively-logged forest contiguous to primary forest. This easily overlooked species may be more resilient to moderate levels of habitat degradation than previously suspected, but extensive deforestation throughout its range justifies its current status as ‘Vulnerable to Extinction’. Received 24 February 2010. Accepted 28 July 2010. Twenty species of Rallidae have become many localities (Ridgely and Greenfield 2001), extinct since 1600, and 33 of the remaining 133 have caused it to be considered ‘Vulnerable to extant species (24%)arecurrentlyglobally Extinction’ globally (BirdLife International 2000) threatened (Taylor 1996). Cryptic habits compli- and ‘Endangered’ in Ecuador (Hilgert 2002). We cate adequate assessment of conservation require- provide the first detailed report of the basic ments for many of these species (BirdLife biology, including nest site selection, nesting International 2000). For example, population size, biology, and habitat use of the Brown Wood Rail. conservation status and, in some cases, even geographic distribution of the six species of Wood METHODS Rail that comprise the South American genus Field work was conducted at Bilsa Biological Aramides are currently unclear (Taylor 1996). Station (79u 459 W, 0u 229 N, 330–730 m eleva- Aramides Wood Rails are relatively large, tion), a 3,500-ha private reserve operated by primarily terrestrial birds that favor more wooded Fundacio´n Jatun Sacha within the 70,000-ha environments than many other rails (Ridgely and Mache-Chindul Ecological Reserve in Esmeraldas Greenfield 2001). Four members of the genus are Province, Ecuador. Bilsa is approximately two- thought to be globally threatened (Taylor 1996), thirds undisturbed humid rain forest and one-third including the Brown Wood Rail (Aramides wolfi). secondary forests (extensively logged with 10– This species is distributed at lower elevations 20 years of regeneration) or selectively-logged along the western slope of the Andes in Colombia, forests (high-graded 10–20 years ago). The Ecuador, and perhaps Peru (BirdLife International surrounding area contains patches of primary, 2000). It is recorded from streams and swampy selectively logged, and secondary forests inter- areas inside humid forest and secondary wood- spersed among areas used for cacao (Theobroma lands (Ridgely and Greenfield 2001). The Brown cacao) cultivation, grazing livestock, and other Wood Rail is reclusive, hard to observe, and agricultural uses. vocalizes infrequently; its basic biology remains We conducted systematic surveys for Brown poorly known. Widespread habitat destruction Wood Rail nests throughout Bilsa from January within its range (Sierra 1996, Conservation 2007 to January 2009. We monitored activity at International 2001) and its apparent absence from nests from blinds using 103 binoculars to record status and behaviors, and recorded nest location 1 Department of Ecology and Evolutionary Biology, and elevation using hand-held global positioning Tulane University, 400 Lindy Boggs Center, New Orleans, system (GPS) units. We quantified habitat char- LA 70118, USA. acteristics around all but one nest by measuring 2 Center for Tropical Research, Rumipamba Oe141 y 10 de Agosto, Quito, Ecuador. canopy height, canopy openness (with a spherical 3 51 rue de Nantouar, 22660 Trelevern, France. densiometer), and number of trees with diameter 4 Corresponding author; e-mail: [email protected] at breast height (DBH) between 10 and 50 cm in 137 138 THE WILSON JOURNAL OF ORNITHOLOGY N Vol. 123, No. 1, March 2011 10-m diameter circular plots and .50 cm in 20-m oval in shape and cream-colored with brown diameter circular plots. We compared these data spotting at the ends; dimensions of one were to equivalent measurements from 87 points at 4.7 3 3.5 cm (Fig. 1A). At least two adults shared 200-m intervals along 17.5 km of trails in Bilsa incubation duties with replacement triggered by that we used to survey for Aramides nests. We sharp, cracking vocalizations by the arriving adult. classified these 87 points as being in primary, At most only a single adult was banded at any given altered, or secondary forest based on visual nest, and we could not confirm whether more than inspection and knowledge of land use history, two birds incubated. Maximum incubation period and used a discriminant analysis to build a observed was 19 days, which should be considered predictive model of group membership based on the minimum for this species because all active habitat characteristics. This model correctly nests had full clutches with discovered. assigned 85% of the 87 training points as primary Two of nine active Wood Rail nests were (n 5 41), selectively-logged (n 5 23) or apparently depredated, one was abandoned, and secondary (n 5 23) forest. The two discriminant six successfully fledged four young each. Hatch- analysis functions were significant (Function 1, ing was synchronous (on the same day) and young Wilks’ Lambda 5 0.280, P , 0.001; Function 2, left the nest within 24 hrs of hatching. Chicks Wilks’ Lambda 5 0.866, P 5 0.008) and were hatched with eyes open and were brooded almost subsequently used to classify the type of forest continuously until departing the nest; we observed where Brown Wood Rail nests were found. no feeding while the chicks were still in the We captured three adult Brown Wood Rails in nest. Chick plumage was dark brown with light mist nets between March 2007 and January 2009, brown longitudinal streaking and highly cryptic and took morphological measurements and ap- (Fig. 1B), similar to that described for other plied three colored leg bands. We applied a Rallidae. At least two adults continued to care lightweight radio transmitter (model PD-2; Holo- for the young for up to 10 days of age. Young hil Systems, Carp, ON, Canada) using a Rappole chicks stayed together and were twice observed harness (Rappole and Tipton 1991) to a breeding among the roots of a palm (Iriartea deltoidea) individual of unknown gender captured on 12 with stilt roots but were cryptic, moved rapidly, March 2008. The 3.8-g radio weighed ,1% of the and difficult to observe. bird’s total body mass. We tracked the individual Nests were open cups atop stumps of fallen using a TR4 receiver and a RA-2AK ‘‘H’’ trees (n 5 5 cases; mean tree DBH 5 31.1 6 antenna (Telonics, Mesa, AZ, USA) until the 16.2 cm, mean tree height 5 1.5 6 0.6 m), at the radio battery failed in November 2008. We intersection of multiple trunks and/or lianas (n 5 suspended radio-tracking during nesting to mini- 3 cases; DBH 5 5.03 6 1.0 cm, height 5 4.1 6 mize disturbance. We obtained locations of the 2.9 m), or in understory shrubs (n 5 8 cases; DBH bird at 30-min intervals during each radio- 5 6.6 6 3.6 cm, height 5 2.8 6 1.4 m). Average tracking session and recorded UTM coordinates nest height was 1.8 6 0.5 m (range 5 1.2–2.6) using a handheld GPS unit. We plotted these above the ground. Nests were constructed primar- coordinates using the Animal Movement exten- ily of large, dead leaves (e.g., Araceae, Cecropia- sion in ArcView GIS 3.2 (ESRI 2006) and ceae, Piperaceae, and ferns) and a few small describe home ranges as minimum convex pieces of dried vine, and were relatively bulky polygons (MCP’s) (Mohr 1947), and 95 and (exterior dimensions: 26.8 6 8.3 3 28.2 6 6.0 3 50% fixed kernel isopleths using least-squares 12.3 6 4.0 cm; interior dimensions: 12.0 6 1.7 3 cross validation (Worton 1989, Seaman and 20.0 6 2.6 3 3.8 6 1.0 cm). The interior was Powell 1996). Means 6 SD are provided for all lined with a mixture of live and dead, smaller measurements. leaves (primarily Melastomataceae). Nests were constructed beneath leaves and ferns in low light RESULTS environments, making them relatively cryptic We found nine active nests and seven addition- despite their large size (Fig. 1C). al nests that had evidence of recent activity but Nests were found in forest areas where which were not active when discovered. Nests elevation averaged 551 6 31 m asl (range 5 were found in February (n 5 3), March (n 5 10), 448–587), canopy height averaged 15.2 6 6.5 m, and April (n 5 3). Median clutch size was four densiometer measures of canopy openness aver- eggs (mean 5 3.7 6 0.7, range 5 2–4). Eggs were aged 14.1 6 6.9%, and there were 3.13 6 2.1 Karubian et al. N BIOLOGY OF BROWN WOOD RAILS 139 FIG.