Importance of Native Bamboo for Understory Birds in Chilean Temperate Forests

Abstract

In South American temperate rainforests, five endemic understory birds (four Rhinocryptidae and one Furnariidae) are often associated with the main understory plant, the native bamboo Chusquea valdiviensis (Poaceae: Bambusoideae). We studied the effects of bamboo cover on species abundance and richness of those understory birds and explored the functions of bamboo as food resource and escape cover. In Chiloé Island (42°S), southern Chile, we selected four old-growth forest patches >100 ha and in each patch conducted bird surveys in six plots with >70% understory cover. Three plots were dominated by native bamboo and three plots had a sparse bamboo cover. Bird abundance (point counts) was significantly correlated with both total understory cover and percentage of bamboo cover but was not correlated with other kinds of understory plant cover. Bird species richness was positively correlated with bamboo cover and negatively correlated with other kinds of understory cover but unrelated to total understory cover. Leaf-gleaners Magellanic Tapaculos (Scytalopus magellanicus), Ochre-flanked Tapaculos (Eugralla paradoxa), and Des Murs's Wiretails (Sylviorthorhynchus desmursii), and the ground-gleaner Chucao Tapaculos (Scelorchilus rubecula) were more abundant in high-bamboo plots; but the ground-gleaner Black-throated Huet-huet (Pteroptochos tarnii) was recorded more times in plots with low-bamboo cover.Availability of invertebrates per unit of understory dry mass did not differ between high- and low-bamboo plots; but plant biomass was greater in high-bamboo plots, so total invertebrate abundance per plot was higher there. Ground-litter invertebrate abundance was similar in all plots. To examine escape-cover preferences, nine captured Chucao Tapaculos were released in front of two different understory scenarios (high-bamboo cover or bamboo-free understory); 88% of released birds moved into bamboo cover. We suggest that the structure of native bamboo understory is critical for the maintenance of four of those species, and retaining bamboo cover in managed stands may help minimize the effect of logging on understory birds.

Evaluating Tolerance of Herbicide and Transplantation by Cane (a Native Bamboo) for Canebrake Restoration

“…A similar situation exits in the Himalayas of India where Red panda (Ailurus fulgens) is threatened by the loss of bamboo habitat due to grazing and development (Pradhan et al 2001). Current forestry practices in Chile are threatening forests with understory bamboos (Reid et al 2004), and restoration of native bamboos may be necessary in the near future if that ecosystem continues to be threatened.…”

Specialization on Guadua Bamboo Seeds by Three Bird Species in the Atlantic Forest of Argentina

“…Bamboo specialization is a prominent feature of the Neotropical avifauna. Avian bamboo specialists occur from the southern temperate forests of Patagonia to the northern tropical rain forests (Lentino & Restall 2003, Reid et al 2004). More than 90 species of Neotropical birds in seven families were classified by Stotz et al (1996) as bamboo-associated.…”

Landscape History, Fragmentation, and Patch Occupancy: Models for a Forest Bird With Limited Dispersal

“…We identified the Chucao Tapaculo as the best subject for intensive research because it is locally abundant and intermediate in both size (40 g) and vagility within the group (Sieving et al 2000). The Chucao is a year-round resident that is territorial and, like other tapaculos in the biome, strongly associated with understory vegetation (Reid et al 2004). Although reproductive success is relatively high in fragmented landscapes (De Santo et al 2002), inter-patch movement is constrained by open habitat, perhaps due to inadequate vegetative cover for predator avoidance.…”

“…Habitat quality for Chucaos is determined largely by understory vegetation density (Reid et al 2004). To incorporate this variable in the model-building process, we visually classified understory density for each censused patch using three categories (''sparse,'' ''dense,'' and ''very dense'') defined by stem density and the degree of contact among branches.…”

“…Sparse understory was easy to walk through, had few stems in contact, and generally lacked dense patches. Given previous knowledge of habitat suitability for Chucaos (Sieving et al 2000, Reid et al 2004), only patches with understory vegetation classified as ''dense'' or ''very dense'' were considered in the analysis. Notes: The percentage change in patch area was measured from 1961 to 1993; distance was measured to the nearest patch of !5 ha; and landscape context variables (mean wooded patch area and percentages of wooded, open, and shrubby habitats) were measured within 100-m and 300-m buffers around each patch.…”