Magellanic Woodpeckers in three national parks of central-southern Chile: habitat effects and population variation over the last two decades

Abstract

ABSTRACT. A major challenge for protected areas is providing wildlife with enough suitable habitat to cope with stochastic environment and increased pressure from the surrounding landscapes. In this study, we addressed changes in local populations of Magellanic Woodpeckers (Campephilus magellanicus) occupying three national parks of central-southern Chile. We compared the breeding and postbreeding abundance of woodpeckers during the 1990s with the present (2016) abundance (n = 4 years), and assessed the extent to which abundance was explained by forest type and quality of foraging habitat (as quantified through the plant senescence reflectance index; PSRI). Results show a distinctive temporal variation in woodpecker abundance at each park, with local populations of Magellanic Woodpeckers declining by 42.2% in Conguillío National Park, but increasing by 34.3% in Nahuelbuta National Park. Woodpeckers responded to forest conditions within each park such that their abundance increased with high quality of foraging habitat, i.e., large PSRI values, and the presence of old-growth Monkey puzzle (Araucaria araucana) -Nothofagus pumilio mixed forest. Anecdotal evidence suggests that populations of woodpeckers in Conguillío National Park might have responded negatively to large-scale disturbances from recent forest fires affecting part of the forest area within park. Because stochastic events seemed to strongly mediate population changes, our findings suggest that regional conservation of Magellanic Woodpeckers requires expanding the current conservation area network in central-southern Chile. Le Pic de Magellan dans trois parcs nationaux du centre-sud du Chili : effets de l'habitat et variation des populations durant les deux dernières décenniesRÉSUMÉ. Les aires protégées font face au défi important de fournir suffisamment d'habitat propice à la faune pour compenser le côté imprévisible de l'environnement et les pressions grandissantes provenant des paysages voisins. Dans le cadre de la présente étude, nous avons évalué les changements advenus dans les populations locales du Pic de Magellan (Campephilus magellanicus) qui fréquentent trois parcs nationaux du centre-sud du Chili. Nous avons comparé les effectifs de ce pic en nidification et en post-nidification dans les années 1990 avec ceux de 2016 (n = 4 années), et évalué dans quelle mesure les effectifs étaient reliés au type forestier et à la qualité des aires d'alimentation (quantifiée par l'indice de réflectance de la sénescence végétale; en anglais PSRI). Nos résultats montrent une variation temporelle des effectifs de pics distincte dans chaque parc : la population locale de Pics de Magellan a diminué de 42,2 % dans le parc national Conguillío, mais a augmenté de 34,3 % dans le parc national Nahuelbuta. Les pics se sont adaptés aux conditions forestières dans chaque parc, de sorte que leur abondance a augmenté là où les aires d'alimentation étaient de grande qualité, c.-à-d. avec des valeurs de PSRI élevées, et en fonction de la présence de forêt mélangée âgée de ...

Improved Campephiline detection: An experiment conducted with the Magellanic Woodpecker

“…Woodpeckers can be challenging to detect or locate (Kosinski & Kempa, ), as they are often secretive (Michalczuk & Michalczuk, ), quiet for long periods, overlooked among large trees that they inhabit (Allen & Kellogg, ), occupying wooded habitats with low visibility, cryptic (Kumar & Singh, ), or wary of humans (Conner, Jones, & Jones, ). Although some species or individuals may be more easily detectable by their drums or vocalizations (e.g., Drever, Aitken, Norris, & Martin, ; Vergara et al, ), not all woodpeckers express the same easily detectable behaviors or only may be more easily detectable seasonally. Additional factors such as small population sizes (Haig, Belthoff, & Allen, ), large home ranges (Tanner, ), low densities (Vergara et al, ), and steep and varying topography increase the difficulty of detecting woodpeckers.…”

“…Although some species or individuals may be more easily detectable by their drums or vocalizations (e.g., Drever, Aitken, Norris, & Martin, ; Vergara et al, ), not all woodpeckers express the same easily detectable behaviors or only may be more easily detectable seasonally. Additional factors such as small population sizes (Haig, Belthoff, & Allen, ), large home ranges (Tanner, ), low densities (Vergara et al, ), and steep and varying topography increase the difficulty of detecting woodpeckers. Therefore, passive methods (i.e., no detection device used) are often less reliable than active methods (i.e., use of detection devices).…”

“…Various survey techniques have been used to estimate woodpecker abundances or densities. Such techniques include a variable‐belt‐width transect method (multiple species; Lammertink, ), playbacks of calls and drums with territory mapping (Black Woodpecker [ Dryocopus martius ]; Kosinski & Kempa, , Pileated Woodpecker [ D. pileatus ]; Renken & Wiggers, ), only playbacks (Pileated Woodpecker; Drever et al, ), and passive point counts followed by an active survey method (multiple species; Kumar & Singh, , Magellanic Woodpecker [ Campephilus magellanicus ]; Vergara et al, ). Despite various methods to detect and estimate woodpecker abundances or densities, to our knowledge, the most effective technique encompassing both calls and drums has never been reported.…”

“…We designed an experiment to determine which of three detection methods would best elicit a MAWO detection. We predicted that the likelihood of a woodpecker detection would be higher with a drumming device (i.e., wooden, acoustical lure device used to simulate a double‐knock [i.e., territorial acoustical signal, Short, ]; Figure ) than either a playback or passive listening, because drumming resonates louder and farther than playbacks, especially in windy environments (Vergara et al, , A. L. Wynia, personal observation). Thus, we also predicted that wind would decrease the likelihood of a detection, because sound attenuates more rapidly in windy conditions.…”

“…Our main objective was to devise a detection technique that could then be used to estimate MAWO abundances or densities to better monitor population changes. Using active detection techniques to increase detection probability and estimate species abundances or densities is not uncommon (e.g., Jakob, Ponce‐Boutin, Besnard, & Eraud, ; Michalczuk & Michalczuk, ; Vergara et al, ). This research can provide valuable information for conservation and land managers that should assist in further protecting the MAWO, its habitat, and by association, co‐inhabitants as well.…”