Range Expansion of the Great-tailed Grackle in the 1900s

In 1900, the range of the Great-tailed Grackle extended north of the Mexican border only into Texas. Since then, it has expanded its range greatly. It now nests in 14 states and has strayed to an additional eight states and three Canadian provinces. Much of this expansion has occurred since 1960. Great-tails often stray far from their normal range, especially in spring. Most of these strays are single individuals. In states where they have nested, breeding birds typically reach the state a few years after the first reports of the species. Great-tailed Grackles do well in a variety of human altered habitats. Their range expansion in North America rivals that of the Cattle Egret both in its extent and as an example of a species thriving while living in close association with humans

Bird use of restored wetlands on Conservation Reserve Program land

From a conservation standpoint, the establishment of the Conservation Reserve Program (CRP) was one of the most significant aspects of the 1985 Food Security Act. Although most of the highly erodible land set aside for ten years in CRP is planted to various upland plants, wetlands are an accepted land use under the program. Because wetlands are one of the most endangered wildlife habitats in North America, and in Iowa in particular, this provision of CRP substantially enhances its value as a conservation program. Nationwide, about 53% of wetlands have been lost; in Iowa more than 90% have been drained for agricultural use. In the north-central states, wetland loss has seriously reduced populations of waterfowl and numerous nongame wildlife species, including birds, insects, and plants

Iowa\u27s Avifauna: Recent Changes and Prospects for the Future

Iowa\u27s avifauna has changed dramatically since 1980. The state list now has 40 additional species and totals 398 species, the most of any vertebrate group. Four species that had not previously nested in Iowa (Ring-billed Gull, Great-tailed Grackle, House Finch, Eurasian Tree Sparrow) and four whose nesting populations had disappeared (Double-crested Cormorant, Sandhill Crane, Piping Plover, Least Tern) now breed regularly here. Little Blue Heron, Cattle Egret, White-faced Ibis, Mississippi Kite, Prairie Warbler, and Red Crossbill nested for the first time but do not have established nesting populations. Trumpeter Swan, Peregrine Falcon, Greater Prairie Chicken, and Sharp-tailed Grouse have been reintroduced to Iowa but nesting populations are not well established. The nesting distributions of Canada Goose, Bald Eagle, Wild Turkey, and Gray Partridge have changed greatly since 1980. Despite these gains in Iowa\u27s avian diversity, one nesting species (Say\u27s Phobe) has disappeared from Iowa since 1980. Thirteen species are listed as endangered, threatened, or of special concern, and 36 other species have nesting populations of fewer than 1,000 pairs. The survival of some of those 49 species is in jeopardy. Another 16 species, although still relatively common, have shown long-term population declines in Iowa and in North America and may be in jeopardy. Iowa\u27s avifauna is dynamic, and changes can be expected to continue in the future as some species thrive, new species colonize the state, and others decline or disappear

Life History of the Creek Chub, with Emphasis on Growth

Age and growth of 151 creek chubs, Semotilus atromaculatus, from the Des Moines River in 1961 were determined by scale and length-frequency methods. The body scale relationship had an intercept of 8.3 millimeters in total length. Chubs reached total lengths of 58, 95, and 128 millimeters at the formation of the first, second and third annuli respectively. Annuli form in May. Weight increased approximately as the cube of the length. The most important food items were plant material, aquatic insects, and, in the case of larger chubs, fish. The chubs were found adaptable in their food habits with the changing conditions of the river

Factors Associated With Occurrence and Density of Wetland Birds in the Prairie Pothole Region of Iowa

Wetlands within wetland complexes in northwestern, north-central, and central Iowa were surveyed for bird use in 1997 and 1998. Species occurrence, species richness, and density of nesting species were related to wetland habitat variables. A habitat diversity index measuring the evenness of distribution of the different habitats within a wetland was the best predictor of species richness in both years. The habitat diversity index was also the best predictor of the occurrence of individual species in both 1997 and 1998. Eight of 11 species (7 3%) in 1997 and 13 of 18 species (72%) in 1998 had greater densities in smaller wetlands. The probability of occurrence and density of individual species also were related to one or more other variables, such as the percent of the wetland that was covered by the different vegetation zones. Most species were more likely to be present and in greater abundance in wetlands that contained more of their preferred nesting habitat. Wetland restoration priorities should emphasize restoring groups of wetlands of a variety of sizes and types to attract the greatest diversity of wetland species as well as greater densities of individual species. If a species is of management concern, those factors that are associated with a greater probability of occurrence and/or a greater density should be considered when selecting sites to restore to wetland conditions

Invasive Species in Iowa: An Introduction

Concern over the increasing spread of invasive species and the potential impacts of those species on native communities has been the subject of several books and hundreds of research papers in recent years. President Clinton\u27s Executive Order on invasive species in February1999 raised national attention to this issue. Natural resource agencies have been plagued by an ever-increasing number of invasive species and now consider this issue the second most important problem (after habitat loss) in their fight to maintain some semblance of natural communities on this planet. One group of experts estimated that in the United States alone, invasives cost more than $100 billion annually (Pimentel et al. 2000). As the global economy continues to grow, it is reasonable to assume that this problem will increase in its severity as additional species extend their ranges

Breeding Bird Populations in Iowa, 1968-1980

A comparison of Breeding Bird Survey (BBS) data in Iowa between 1968-1970 and 1978-1980 suggests that 19 species have increased in numbers and that 18 have declined over that period. Most species showing increases are associated with agricultural and grassland habitats. Most species showing decreases are associated with agricultural and edge-oldfield habitats. A variety of factors is probably responsible for these declines. BBS results are fairly consistent with the National Audubon Society\u27s Blue List - birds thought to be declining - but show little correlation with that group\u27s list of species of special concern. The BBS detected at least 68% of the birds known to breed in Iowa, although not all of those were detected each year. About the same number of species were reported from each of five regions in the years considered, although the same species were not seen in all areas. Still, 73 species reported in all five regions dominate the state\u27s avifauna. Some biases related to the species\u27 detectability and observer competence are evident in the data. Overall, BBS data do seem to be meeting their goal of providing quantitative information useful in detecting long-term changes in bird populations

Invasive Birds in Iowa: Status, Problems, and Threats

A total of 18 invasive bird species has been introduced into or have expanded their range to include Iowa. These include ten non-North American species, one North American species that has been displaced and now is established in Iowa, and seven native species that have been released to reestablish Iowa populations. Twelve of those are regularly occurring species in Iowa, and they comprise 3.0% (12 of 404) of the species known from Iowa and 5% (10 of 199) of Iowa\u27s nesting avifauna. These percentages are similar to those found in neighboring states. Several more species are likely to become established in the near future. Two invasive species, European Starling (Sturnus vulgaris) and House Sparrow (Passer domesticus), are among the most numerous species found in Iowa and have negative effects on other species. Most of the other invasive bird species seem to have little effect on other bird species. Two species, Mute Swan (Cygnus olor) and Eurasian Collared-Dove (Streptopelia decaocto), are close to becoming established in Iowa. Both have the potential to be harmful to other bird species

Iowa\u27s Avifauna: Changes in the Past and Prospects for the Future

Since the time of settlement, at least 17 species (9%) of birds have disappeared as nesters in Iowa. Nine species were lost before 1900, another two before 1950, and six since 1950. Five species have been successfully introduced into Iowa, and four of these now are abundant in the state. A number of other species have benefited from human development and have increased in numbers since settlement. An additional 29 species have populations that seem endangered or threatened and may disappear before the end of this century

Changes in Land Cover and Breeding Bird Populations with Restoration of Riparian Habitats in East-central Iowa

Conversion of Midwestern riparian areas for agricultural production has greatly altered their function and suitability for birds and other wildlife. Recently, however, restoration of riparian functions has been a major focus of land management agencies in the Midwest. We used historic land-use data to describe land-cover changes since European settlement and the subsequent effects of habitat restoration efforts on the landscape along a section of the Iowa River in east-central Iowa. We then used bird-density data collected in a subset of the study area in 2001 and 2002 to estimate changes in breeding bird populations of the entire study area resulting from these habitat restoration efforts. Before settlement, the (\u3e24,000 ha) Iowa River Corridor was dominated by herbaceous vegetation (72%), with wooded areas accounting for less than one-third of the area. Between the mid-1800s and 1992, agricultural conversion decreased the amount of herbaceous cover by \u3e75%, and the cover of woody vegetation increased by \u3e25%. After the 1993 flood, establishment of USDA conservation easements increased the amount of herbaceous cover in the corridor by \u3e135% (\u3e5,000 ha). Populations of most grassland and wetland bird species in the corridor (13 of 17) increased with habitat restoration, although some species associated with open habitats, such as those that often breed in rowcrop fields, decreased. We estimated that these restored habitats provide habitat for \u3e12,000 additional birds of grassland- or wetland-dependent species in the Iowa River Corridor, 5,000 of which are members of eight species that are of moderate or high conservation priority. An understanding of presettlement land cover, the extent of land-cover alteration, and the effects of habitat restoration on the landscape and breeding bird populations provides a useful guide for both evaluating the efficacy of past restoration and for guiding future conservation and restoration efforts