State of the Greater Fundy Ecosystem - Pileated Woodpecker

GREATER FUNDY ECOSYSTEM RESEARCH PROJECT

UNB Faculty of Forestry and Environmental Management

State of the Greater Fundy Ecosystem

Shelter Tree use by Pileated Woodpecker
in Fundy NP and the GFE

E. Jane Watts, Stephen Flemming, and Gillian Holloway
Fundy National Park, P.O. Box 40, Alma, N.B. E0A 1B0

Pileated Woodpecker
(Photo: Fundy NP)

The Pileated Woodpecker is an important member of healthy older forest communities. As a primary tree cavity excavator, the Pileated Woodpecker plays a significant ecological role by excavating nest and roost cavities that are subsequently used by other birds and small mammals.

Pileated Woodpeckers are dependent on large dead or aging trees and coarse woody debris for nesting, roosting, and foraging (Bull and Meslow, 1977; Conner, 1979;Bull et al., 1990; Renken and Wiggers, 1993). Because of this dependence, they are considered to be one of the bird species most sensitive to intensive forest management (Bull and Meslow, 1977). Intensive forest management reduces the proportion of the landscape containing old-growth forest or forest stands with old-growth attributes. Current forest management is often based on short rotations that can decrease the amount of old forest. Stands are often harvested before they can obtain sizes and structural characteristics suitable for use by Pileated Woodpeckers.In this study we examined the nesting and roosting (shelter tree) habitat requirements of the Pileated Woodpecker in and surrounding Fundy National Park (Fundy NP) from 1994-96.

GOAL

Our goal was to indentify the tree species and tree characteristics used by Pileated Woodpeckers for shelter, and to determine if differences exist in the use of these trees between the Park and the surrounding fragmented forest.

METHODS

Our study inventoried the characteristics (species, dbh, decay class, height) of 108 Pileated Woodpecker shelter trees.

RESULTS

It was found that mature and overmature deciduous forests were the preferred habitat type. The most commonly used species were Sugar Maple, Yellow Birch, and Trembling Aspen. Shelter trees were significantly different from trees adjacent to them, being larger, shorter and more decayed (Table 1). In addition, over half of the shelter trees examined were dead and had broken tops, whereas the adjacent trees were usually alive and intact (Table 1).

Pileated Woodpecker in a tree cavity
(Photo: Parks Canada)

In southern New Brunswick, the most important characteristics for shelter trees appeared to be size and decay. As the Pileated Woodpecker is a large bird, it requires a large diameter tree to accomodate its shelter cavity. In our study, the average dbh for shelter trees was 49.0 cm. The smallest shelter tree examined was a 28.0 cm Trembling Aspen, and the largest was a 95.0 cm Sugar Maple. The majority of shelter trees inventoried during this study were dead or declining, with broken tops and broken or dead branches. These external characteristics suggest that many of the shelter trees were infected with heartrot. Decayed wood (especially in hardwoods) may be easier to excavate by Pileated Woodpeckers, therefore reducing the energy requirements needed to create a suitable shelter cavity.

In this study, the characteristics of shelter trees differed between tolerant and intolerant hardwood species. Tolerant hardwood species, including Sugar Maple and Yellow Birch, were usually larger in diameter (mean dbh 54 cm versus 39 cm) and more decayed than intolerant hardwood species, such as Trembling Aspen. The majority of tolerant hardwoods used for shelter were dead (63% versus 38%) and had broken tops (61% versus 26.5%), compared to intolerant hardwoods which were generally alive or declining and intact.

IMPLICATIONS FOR MANAGEMENT

Few differences were evident when the characteristics of shelter trees were compared between the Park and the surrounding fragmented forest. Trembling Aspen were used more frequently outside the Park, presumably due to their increased availability. That few differences were evident between the two landscapes suggests that Pileated Woodpeckers in southern New Brunswick have specific habitat requirements. It appears that these can only be met in deciduous forests with older forest structural characteristics (i.e., large decayed trees).

- Table of Contents

- View other case studies

- Bibliography