Molt And Aging Criteria For Four North American Grassland Passerines

Prairie and grassland habitats in central and western North America have declined substantially since settlement by Europeans (Knopf 1994) and many of the birds and other organisms that inhabit North American grasslands have experienced steep declines (Peterjohn and Sauer 1999; Johnson and Igl 1997; Sauer, Hines, and Fallon 2007). The species addressed here, Sprague's Pipit (Anthus spragueii), Grasshopper (Ammodramus savannarum) and Baird's (A. bairdii) sparrows, and Chestnut-collared Longspurs (Calcarius ornatus), are grassland birds that are of special conservation concern throughout their ranges due to declining populations and the loss of the specific grassland habitats required on both their breeding and wintering ranges (Knopf 1994, Davis and Sealy 1998, Davis 2003, Davis 2004, Jones and Dieni 2007). Population-trend data on grassland birds, while clearly showing declines, provides no information on the causes of population declines. Without demographic information (i.e., productivity and survivorship), there are no means to determine when in their life cycle the problems that are creating these declines are occurring, or to determine to what extent population trends are driven by factors that affect birth rates, death rates, or both (DeSante 1995). For migratory birds, population declines may be driven by factors on breeding grounds, during migration, and/or on wintering grounds. Lack of data on productivity and survivorship thus impedes the formulation of effective management and conservation strategies to reverse population declines (DeSante 1992). Furthermore, if deficiencies in survivorship are revealed, management strategies may need to address habitats on both breeding and non-breeding grounds, as well as along migratory pathways. One technique that helps inform management strategies is the biochemical analysis of isotopes and genetic markers, from the sampling of individual feathers from live birds (Smith et al. 2003, Pérez and Hobson 2006; Appendix). Determining demographic parameters and effectively sampling feathers to reveal connectivity between breeding and wintering grounds requires detailed knowledge of molt patterns and age determination criteria for the target species, in the hand. For example, productivity, survivorship, and territory acquisition may all be age-dependent, with first-year birds showing different patterns and responses than older birds. In many cases it may be possible to sample both a feather grown on the breeding grounds and one grown on the wintering grounds from a single individual, but knowledge of age-specific molt patterns, as well as an ability to recognize different feather generations, is needed to accomplish such a task. While some information on molt and aging criteria exists for grassland passerine species (Pyle 1997a), these species have been rarely captured during mark-recapture studies (Jones et al. 2007) and this information thus needs refining. There is a need for additional resources to assist field workers in determining molt patterns and age in captured individuals. Our objective is to describe molt and aging criteria for four grassland passerine species with the aid of digital photographs taken in the field. We hope that this document will be useful for researchers studying grassland species through capture and banding of live individuals on either the breeding or the wintering grounds. We present a general section on molt and aging techniques, followed by specific accounts for the four species treated: Sprague's Pipits, Grasshopper and Baird sparrows, and Chestnut-collared Longspur. We also provide a brief protocol on collecting feather samples (Appendix).

Citing the lesser-known role of molt in identifying and understanding birds, a detailed reference comprehensively illuminates four key strategies about the molt cycle to provide insights into North American bird history, habitat and migratory patterns.

Molt is an important avian life history event in which feathers are shed and replaced. The timing, duration, seasonality, extent and pattern of molt follows certain strategies and this book reviews and describes these strategies for nearly 190 species based on information gathered from a 30-year study of Central Amazonian birds. Most species accounts are illustrated with several color photos focusing on wing and tail feather molt, molt limits, and how to use these patterns to accurately age birds. Published in collaboration with and on behalf of the American Ornithological Society, this volume in the highly-regarded Studies in Avian Biology series is a rich source of life history information for ornithologists working on tropical birds.

To most observers, molt seems an overwhelming subject. But birders use many aspects of molt more than they realize—to distinguish juvenile birds from adults, to pick out an individual hummingbird from among dozens visiting a feeder, and much more. And for those whose interest goes beyond simply identifying birds, questions such as What triggers molt to start? How fast do feathers grow? and How long do they last? offer a fascinating window into the lives of birds. Put plainly, molt relates in some way to everything a bird does, including where it lives, what it eats, and how far it migrates. Here, for the first time, molt is presented for the nonscientist. Molt is very orderly and built on only four underlying strategies: simple basic, complex basic, simple alternate, and complex alternate. This book clearly lays out these strategies, relates them to aspects of life history, such as habitat and migration, and makes this important subject accessible.

This book documents the biology of six species of New World quails that are native to North America north of Mexico (mountain, scaled, Gambel's, California, and Montezuma quails, and the northern bobwhite), three introduced Old World partridges (chukar, Himalayan snowcock, and gray partridge), and the introduced common (ring-necked) pheasant. Collectively, quails, partridges, and pheasants range throughout all of the continental United States and the Canadian provinces. Two of the species, the northern bobwhite and ring-necked pheasant, are the most economically important of all North American upland game birds. All of the species are hunted extensively for sport and are highly popular with naturalists, birders, and other outdoor enthusiasts.

The volumes in the Birds of Ontario series summarize life history requirements of bird species that are normally part of the ecology of Ontario. This is the second volume in the series and completes the treatment of the nonpasserine bird species occurring in Ontario on a regular basis. Information on habitat, limiting factors, and status is summarized for 83 species in this volume. These topics are covered for the three primary avian seasons: breeding, migration, and winter. Habitat, nest sites, territoriality, site fidelity, annual reproductive effort, habitat loss and degradation, environmental contaminants, and a variety of other topics are covered in the species accounts. Maps depicting breeding and wintering range are presented for most species along with drawings by Ross James. Birds of Ontario is an essential reference source for wildlife biologists, environmental consultants, and planners preparing or reviewing environmental impact statements and environmental assessments. Serious birders will find the volumes of interest as well. Although the books focus on Ontario birds, the information is highly relevant to adjacent provinces and states.