Partridge (Dendrortyx Macroura) in a Temperate Coniferous Forest
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J. Field Ornithol. 75(4):345±352, 2004 Abundance and distribution of the Long-tailed Wood- Partridge (Dendrortyx macroura) in a temperate coniferous forest Gilberto ChaÂvez-LeoÂn1,3 and Alejandro VelaÂzquez2 1 Instituto Nacional de Investigaciones Forestales, AgrõÂcolas y Pecuarias, Av. Latinoamericana 1101, Uruapan, MichoacaÂn 60025, Mexico 2 Instituto de GeografõÂa, Universidad Nacional AutoÂnoma de MeÂxico, Morelia, MichoacaÂn, Mexico Received 24 July 2003; accepted 5 February 2004 ABSTRACT. The Long-tailed Wood-Partridge (Dendrortyx macroura) is a species endemic to Mexico, inhabiting dense coniferous forests of the Trans-Mexican Volcanic Belt and the Sierra Madre del Sur, of which little is known about its ecology and conservation status. The abundance and density of the Long-tailed Wood-Partridge was estimated by point counts with playback distance sampling from March±October of 1998±2000 in a temperate coniferous forest managed for timber production by a Mexican indigenous community. The average detection rate was 0.31 individuals per point, resulting in a mean estimate for population density of 20.9 birds/km2 and a mean population estimate of 2679 individuals, estimated using the half-normal key function with cosine adjustments. Density estimates of the Long-tailed Wood-Partridge were 8 individuals/km2 in dry, open, scrubby habitats with deep ash and sand volcanic deposits subject to intense human use and in closed canopy, humid forests with moderate human disturbance. Density estimates were 14.6 and 21.5 individuals/km2 in humid, closed canopy, multi-strati®ed forests. The latter areas are recommended as the core area for protection of the Long-tailed Wood-Partridge. SINOPSIS. Abundancia y distribucioÂn de Dendrortyx macroura en un bosque conifero templado La perdiz Dendrortyx macroura, es una especie endeÂmica a MeÂxico, de la cual se sabe muy poco de su ecologõÂa y estatus. Esta habita los bosques densos de conõÂferos que se encuentran en la la faja volcaÂnica trans-mexicana y la Sierra Madre del Sur. La abundancia y densidad del ave se estimo utilizando conteos de punto y con la ayuda de grabaciones de su vocalizacioÂn y estimados de distancias de respuestas. El trabajo se llevo a cabo de marzo±octubre de 1998±2000 en un bosque de conõÂferos manejado para obtener madera por una comunidad indõÂgena mexicana. La tasa de deteccioÂn promedio fue 0.31 individuos por punto, dando como resultado un estimado promedio de densidad de 20.9 individuos/km2 y una poblacioÂn promedio para toda la localidad de 2679 individuos, estimada. La densidad de aves fue de 8 individuos/km2 en habitat arbustivo, seco y abierto con depoÂsitos profundos de ceniza y depoÂsitos arenosos volcanicos que estaÂn sujetos a uso intensivo por parte de humanos y en habitat con docel cerrado, huÂmedo y con disturbio moderado por parte de humanos. El estimado de densidad fue de 14.6 y 21.5 individuos/km2 en habitat con docel cerrado y altamente estrati®cado. Se recomienda la proteccioÂn, en particular, de los dos uÂltimos tipos de habitats para este tipo de perdiz. Key words: density estimates, Dendrortyx macroura distance sampling, Mexico, point transects, playback The Long-tailed Wood-Partridge (Dendrortyx abundant in the dense thickets of mountain macroura) is a Mexican endemic species pro- forests; on the contrary, Johnsgard (1973) sug- tected since 1994 (SEMARNAT 2002). It is gested that even in good habitats, its population mainly threatened by habitat loss and pertur- density was probably only about ®ve pairs per bation (del Hoyo et al. 1994; McGowan et al. km2, and McGowan et al. (1995) estimated a 1995; Fuller et al. 2000). Parker et al. (1996) total population size between 20,000±200,000 considered this species to be of ``medium'' sen- individuals and suggested that population size sitivity to human disturbance and of a ``medi- was probably decreasing. More accurate esti- um'' conservation and research priority. There mates of population density for Long-tailed are, however, no systematic quantitative popu- Wood-Partridges are necessary to determine re- lation density estimates for this species, and search and conservation priorities. previous density estimates vary widely. For in- This wood-partridge inhabits temperate for- stance, Leopold (1959) concluded that it was ests with dense shrubs throughout the Trans- Mexican Volcanic Belt and the Sierra Madre del 3 Corresponding author. Email: calgpmx@yahoo. Sur (AOU 1998), an area rich in endemic plant com and animal taxa (Escalante et al. 1993; Toledo 345 J. Field Ornithol. 346 G. ChaÂvez-LeoÂn and A. VelaÂzquez Fall 2004 and OrdoÂnÄez 1993) and of high economic val- bus, P. leiophylla, P. michoacana, P. douglasiana, ue (Style 1993). Industrial forestry (mainly tim- Abies religiosa, Carpinus carolineana, Quercus ber and pine-resin tapping) in this part of Mex- laurina, Q. rugosa, Q. candicans, Clethra mexi- ico has been active for several decades; however, cana, Arbutus xalapensis and Alnus jorullensis.A there has been little research into its effects on dense shrub layer, present in most of these plant native ¯ora and fauna. communities, is dominated by Baccharis hete- Logging during the last century has per- rophylla, Cestrum nitidum, Ternstroemia pringlei, turbed most temperate forests in Mexico, and Stevia rhombifolia, Arctostaphylos discolor, and few forest tracts remain uncut. For example, of Eupatorium petiolare. The herbaceous layer is the original 93,560 km2 of pine-oak habitat in dominated by Piptochaetium virescens, Dryopte- the Sierra Madre Occidental, 571 km2 re- rus sp., Phacelia platycarpa, Asplenium praemor- mained as old-growth in 1995, a reduction of sum, Aegopogon cenchroides, and Galium mexi- 99.4% (Lammertink et al. 1996). About 80% canum. These forests are managed for timber of forest area in Mexico is controlled by indig- production using a selective cutting forestry sys- enous communities and peasants in collective tem, based on a 50-yr term with a 10-yr regen- ownership (Thoms and Betters 1998). This im- eration scheme. plies that natural resource management by these Field methods. Wood-partridge abun- rural communities will de®ne the future con- dance and distribution were estimated using the servation of forest ecosystems in Mexico (Bocco point transect or variable circular plot method et al. 2000). Therefore, conservation efforts (Reynolds et al. 1980; Bibby et al. 2000; Buck- cannot rely only on protected reserves, but land et al. 2001) with tape playback. The use must focus also on unprotected areas, which of playback to elicit vocalizations is an effective comprise most of the remaining habitat. The method to detect elusive or secretive birds, such objective of this study was to document the dis- as the Long-tailed Wood-Partridge, and has tribution, density, and abundance of a popula- been used to estimate the abundance of various tion of the Long-tailed Wood-Partridge in a bird species (Johnson et al. 1981; Marion et al. temperate coniferous forest managed for timber 1981; Legare et al. 1999; Bibby et al. 2000; production by the indigenous community of Turcotte and Desrochers 2002). Nuevo San Juan Parangaricutiro, MichoacaÂn, Vocalizations of the Long-tailed Wood-Par- Mexico. tridge were recorded previously in the study area with a Marantz PMD222 tape recorder STUDY AREA AND METHODS and a Sennheiser ME62 microphone equipped with a 58.4-cm Telinga parabola (following The study was conducted in lands owned by Budney and Grotke 1997). Best-quality record- the indigenous community of Nuevo San Juan ings were transferred to a three-minute endless Parangaricutiro (NSJP), located in the sub-hu- cassette and used for playback with a cassette mid temperate zone of the southwestern edge player (Sony Walkman WM-FX193) connected of the Trans-Mexican Volcanic Belt, western to a portable mini speaker (Sony SRS-A21). MichoacaÂn, Mexico (Fig. 1). The area is be- During a two-month pilot study, most tween 198219Nto198349N and 1028089Wto wood-partridges responded within 2±4 min of 1028179W. Elevations range from 1800 m to playback and almost none after 5 min (G. ChaÂ- 3100 m with a mean annual precipitation of vez-LeoÂn, unpubl. data). Considering this, and 1200 mm concentrated from May to October the risk of behavioral disturbance when play- and mean annual temperatures not greater than back is used for extended periods of time 158C. The area is about 180 km2 in size, sup- (Bibby et al. 2000), each point count was lim- porting temperate forests of pine, ®r, oaks, and ited to duration of 5 min. In each point the agricultural lands. Agricultural clearings and cassette tape was played for one minute (three eruptive events of the ParicutõÂn volcano (1943± songs) followed by one minute of silence to de- 1952) have reduced the original forest area to tect wood-partridge vocalizations. This was re- approximately 128 km2 (Fig. 1). Fregoso (2000) peated once after which the cassette tape was described eight plant associations (Table 1) for played for 30 s followed by an additional 30 s the area. The tree layers of these forests are of silence. Since most individuals (93%) were dominated by Pinus montezumae, P. pseudostro- detected aurally, the distance to each respond- Vol. 75, No. 4 Abundance of the Long-tailed Wood-Partridge 347 Fig. 1. Study area of Comunidad IndõÂgena de Nuevo San Juan Parangaricutiro (NSJP), MichoacaÂn, Mexico. Gray shading in NSJP indicates forest cover; areas in white include agriculture, lava, and volcanic ash ®elds. ing Long-tailed Wood-Partridge was estimated. beyond 150 m, distance estimates were cate- Training to estimate distances was conducted gorized as 0±25 m, 25±50 m, 50±100 m, and during the pilot study. Because the recorder at 100±150 m. maximum volume could not be heard clearly Data were collected using the methods out- Table 1. Plant communities identi®ed by Fregoso (2000) in Comunidad IndõÂgena de Nuevo San Juan Parangaricutiro, MichoacaÂn, Mexico.