Using Atlas Data to Model the Distribution of Woodpecker Species in the Jura, France

Breeding bird atlases providing distribution data at a regional scale are becoming increasingly common. To assess the ability of such data to develop bread-scale bird-habitat models, we used data from a breeding bird atlas and landscape variables obtained From a geographic information system (GIS) to study the distribution of seven woodpecker species in the Jura, France: the Black (Dryocopus martins), Green (Picus viridis). Grey-headed (P. canus), Great Spotted (Dendrocopos major), Middle Spotted (D. medius), and Lesser Spotted (D. minor) Woodpeckers, and the Wryneck (Jynx torquilla). We used logistic regression to develop predictive models from variables that described each 575-ha atlas cell in terms of forest composition, forest class richness, edge density, and elevation. For all seven species, prediction rates were better than chance; however, improvements over chance classification varied from 14-39%, indicating that predictive ability was species-specific. From our study, we identified limitations inherent to working with gridded data, including grid positioning problems and inability to compute spatial variables. In spite of these limitations, our models could be used for simulations, to improve the atlas itself, and to identify potential suitable habitat

Scaling of Muscle Composition, Wing Morphology, and Intermittent Flight Behavior in Woodpeckers

Existing theory and empirical evidence suggest that body size should have a profound influence upon the composition of flight muscles and the performance of intermittent flight in birds. I examine the relationships between functional morphology and intermittent flight behavior within a closely-related group of birds using six species of woodpeckers (Picidae): Downy Woodpecker (Picoides pubescens, 27.2 g), Red-naped Sapsucker (Sphyrapicus nuchalis, 47.4 g), Hairy Woodpecker (P. villosus, 70.5 g), Lewis\u27 Woodpecker (Melanerpes lewis, 106.6 g), Northern Flicker (Colaptes auratus, 148.1 g), and Pileated Woodpecker (Dryocopus pileatus, 262.5 g). In woodpeckers with a body mass less than 100 g, the pectoralis muscle was composed mostly of red (R) fibers, with intermediate (I) fibers either absent or restricted to lateral regions. R and I fibers were found in all regions of the pectoralis in the larger species. Positive scaling of the percent and cross-sectional diameter of I fibers may explain why species larger than 100 g flap-bounded when theory predicts they should not have sufficient power. Differences were evident in staining characteristics of I fibers among (but not within) species. Phylogenetic effects were apparent because hypothesized sister taxa shared similarities in muscle composition. Internal and external wing dimensions scaled according to the predictions of geometric similarity, but the Red-naped Sapsucker and Lewis\u27 Woodpecker possessed slightly higher wing-shape indices (narrower, more-pointed wings) than the other species, which may reflect migratory and flycatching behavior as well as phylogeny. All of the species exhibited flap-bounding. The number of flaps in a flapping phase, wingbeat frequency, flapping-phase duration, and bounding-phase duration all scaled negatively with body mass, whereas the percent time spent flapping and flight speed scaled slightly positively. Lewis\u27 Woodpecker was unusual in its intermittent flight behavior by spending more time flapping, using lower wingbeat frequencies and flying slower than would be expected for its body mass. It was the only species to pursue flying insects using highly maneuvered flights including extended glides, although the Red-naped Sapsucker was observed to flycatch without gliding. Slow flight speed, rather than wing design, was related to gliding in the Lewis\u27 Woodpecker. I fibers in the pectoralis of the Lewis\u27 Woodpecker were unique in showing intense glycolytic potential, perhaps reflecting the species\u27 foraging style

Take-off mechanics in hummingbirds (Trochilidae)

Initiating flight is challenging, and considerable effort has focused on understanding the energetics and aerodynamics of take-off for both machines and animals. For animal flight, the available evidence suggests that birds maximize their initial flight velocity using leg thrust rather than wing flapping. The smallest birds, hummingbirds (Order Apodiformes), are unique in their ability to perform sustained hovering but have proportionally small hindlimbs that could hinder generation of high leg thrust. Understanding the take-off flight of hummingbirds can provide novel insight into the take-off mechanics that will be required for micro-air vehicles. During take-off by hummingbirds, we measured hindlimb forces on a perch mounted with strain gauges and filmed wingbeat kinematics with high-speed video. Whereas other birds obtain 80–90% of their initial flight velocity using leg thrust, the leg contribution in hummingbirds was 59% during autonomous take-off. Unlike other species, hummingbirds beat their wings several times as they thrust using their hindlimbs. In a phylogenetic context, our results show that reduced body and hindlimb size in hummingbirds limits their peak acceleration during leg thrust and, ultimately, their take-off velocity. Previously, the influence of motivational state on take-off flight performance has not been investigated for any one organism. We studied the full range of motivational states by testing performance as the birds took off: (1) to initiate flight autonomously, (2) to escape a startling stimulus or (3) to aggressively chase a conspecific away from a feeder. Motivation affected performance. Escape and aggressive take-off featured decreased hindlimb contribution (46% and 47%, respectively) and increased flight velocity. When escaping, hummingbirds foreshortened their body movement prior to onset of leg thrust and began beating their wings earlier and at higher frequency. Thus, hummingbirds are capable of modulating their leg and wingbeat kinetics to increase take-off velocity

Bird Populations in Logged and Unlogged Western Larch/Douglas-fir Forest in Northwestern Montana

Of 32 species of abundant breeding birds, populations of 10 species differed significantly between small cutting units and adjacent uncut forest. Foliage foragers and tree gleaners were less abundant in cutting units, while flycatching species and ground foragers were more common there. Of nesting guilds, conifer tree nesters were least abundant in cutting units, and ground nesters were more common there. Results suggest that bird management should consider diverse community-level habitat needs and that if maintenance of tree-dependent species is important, broadleaf trees and snags of all species should be retained

Maintaining Bird Diversity in Western Larch/Douglas-fir Forests

Bird occurrences were evaluated under four stand conditions in western larch/Douglas-fir forests: clearcut, partial cut, unlogged (fragmented), and contiguous forest. Frequencies were noted for foraging guilds, tree gleaners, flycatchers, nesting guilds, tree drillers, and primary cavity nesters. Managers should consider a diversity of habitat conditions if maintaining habitat for bird species is an objective