Population Declines and Range Contractions among Lowland Farmland Birds in Britain

We used extensive atlas and census data to assess trends in the distribution and population levels of birds on lowland farmland in Britain between the late 1960s and early 1990s. Many species of farmland birds have become less widespread or have declined in numbers, or both, but few have become more wide-spread or have increased. Of the 28 species classified as farmland birds the distributions of 24 contracted between 1970 and 1990. Of the 18 farmland species for which it was possible to assess population change, 15 were less abundant in 1990 than in 1970. Seven of the species were estimated to have undergone population decreases of at least 50%. Farmland species showing the largest population declines tended also to show substantial range contractions. Farmland species underwent an appreciably larger contraction of distribution than species associated with any other habitat. Furthermore, farmland species tended to decrease in abundance, whereas woodland species tended to increase. Population declines among farmland birds became evident in the mid- to late 1970s, a period when several fundamental changes were taking place in British agricultural practices. These included a great reduction in the spring sowing of cereals, a simplification of crop rotations, increased use of chemical pesticides and inorganic fertilizers, and more-intensive grassland management. We suggest that the declines of farmland bird species have been caused or aggravated by this pervasive intensification of agriculture. Existing research on declining farmland birds, however, indicates that there is no single mechanism underlying the population changes. We identify priorities for research, focusing mainly on relationships between bird populations and agricultural practices, but we also recognize a need for a better understanding of the role of predation.     

On the mating system of the cooperatively breeding saddle-backed tamarin (Saguinus fuscicollis)

Summary This paper reports on 5 years of observatiors of individually marked saddle-backed tamarins (Saguinus fuscicollis, Callitrichidae). Although callitrichids have long been presumed to have a monogamous social system, this study shows that the breeding structure of saddle-back tamarin groups is highly variable. Groups most commonly include two or more adult males and a single reproductive female, but occasionally contain only a single pair of adults, or less often, two reproductively active females and one or more males. Data on group compositions, group formations, intergroup movements and copulations show that the social and mating systems of this species are more flexible than those of any other non-human primate yet studied. Infants (usually twins) were cared for by all group members. There were two classes of helpers: young, nonreproductive individuals who helped to care for full or half siblings, and cooperatively polyandrous males who cared for infants whom they may have fathered. The observations suggest that non-reproductive helpers may benefit from their helping behavior through a combination of inclusive fitness gains, reciprocal altruism, and the value of gaining experience at parental care.     

The effects of military tank traffic on prairie: A management model

The effect of various frequencies and seasons of military tank traffic on native mixed-grass prairie was examined in a randomized and replicated field experiment. Vegetation (in 10×10 m plots) was subjected to tank traffic at the following rates: (a) one pass per day of training from May until August; (b) one pass per day in May and June; (c) one pass per day in July and August; (d) one pass every three weeks from May until August; (e) zero (control). Species composition and the amount of bare ground were found to vary significantly with traffic frequency. Plant species alien to North America invaded plots subjected to spring driving. Regression analysis showed spring driving to produce more bare ground than summer driving. The regression models suggested that much higher intensities of training could be conducted without damage if spring driving were avoided. Regression models were also used to estimate the frequency of traffic associated with a significant change in species composition, where species composition was expressed as the ratio ofBouteloua gracilis toStipa spartea, an indicator of disturbance-induced change in prairie vegetation. This relationship predicted the capacity of the vegetation of a training area of any given width to support tank traffic without changing species composition. The predictive ability of the model was tested by comparing predicted traffic capacities with the amount of traffic actually applied to two training areas in 1986. Where traffic capacity was exceeded, the model successfully predicted a significantly higher frequency of bare ground and ratio ofBouteloua gracilis toStipa spartea.     

USING INFILTRATION ENHANCEMENT AND SOIL WATER MANAGEMENT TO REDUCE DIAZINON IN RUNOFF1

ABSTRACT: Pesticide runoff from dormant sprayed orchards is a major water quality problem in California's Central Valley. During the past several years, diazinon levels in the Sacramento and San Joaquin Rivers have exceeded water quality criteria for aquatic organisms. Orchard water management, via post‐application irrigation, and infiltration enhancement, through the use of a vegetative ground cover, are management practices that are believed to reduce pesticide loading to surface waters. Field experiments were conducted in Davis, California, to measure the effectiveness of these management practices in reducing the toxicity of storm water runoff. Treatments using a vegetative ground cover significantly reduced peak concentrations and cumulative pesticide mass in runoff for first flush experiments compared with bare soil treatments. Post‐application irrigation was found to be an effective means of reducing peak concentrations and cumulative mass in runoff from bare soil treatments, but showed no significant effect on vegetated treatments.     

DEVELOPMENT AND EVALUATION OF A DIMENSIONLESS UNIT HYDROGRAPH1

ABSTRACT: A generalized unit hydrograph method is developed and evaluated for ungaged watersheds. A key component in this method is the value of a dimensionless storage coefficient. Procedures to estimate this coefficient are given using calibrated values from 142 rainfall-runoff events gaged in watershed located mainly in the Eastern US. Only limited success was obtained in predicting this storage coefficient. Thirty-seven, independent rainfall-runoff events were used to test the proposed technique. The generalized unit hydrograph predicted the observed runoff hydrographs fairly well with considerable improvement in accuracy over the SCS dimensionless unit hydrograph. Approximately one-half of test storms had percent errors in predicted peak flow rates that were less than 34 percent compared to percent error of 88 percent with the SCS method.     

A LAND-USE POLICY BASED ON WATER SUPPLY1

ABSTRACT: Santa Fe Country, New Mexico, has adopted a land-use policy in which zoning densities provide a balance between the water use on a parcel of land and the water supply available bencath that land. In two of four mapped hydrologic zones, ground water in storage will be allowed to be mined to exhaustion in 100 years (40 years in urban areas). Elsewhere, the policy is for a steady state with use balanced by recharge. Equations to determine storage or recharge can be solved using site specific data or regional estimates of hydrologic conditions. Substantial reductions in the lot size requirements are allowed if water conservation convenants are adopted. Public acceptance indicates that the policy successfully integrates technical and political concerns. It is simple to administer, yet reflects widely expressed public goals and values.     

Capturing change in European food assistance practices: a transformative social innovation perspective

The food system’s decreasing ability to deliver food security has led to the emergence of food assistance initiatives. Food assistance is highly contested; as some argue, it is a “failure of the state”, while others regard food assistance to be an “extension of the welfare state”. Either way, research suggests that actors within food assistance are rethinking their role in the food system. In this paper, we study three food assistance initiatives, in the Netherlands, Italy and Ireland, that perform new food assistance practices while embedded in specific institutional contexts, and analyse their potential to transform the food system, drawing on Transformative Social Innovation theory. Building on transition and social innovation theory, this recently developed theory distinguishes different levels within systems, named “shades of change”, that are associated with societal transformation. By exploring these “shades” of change in the analysis, we describe aspects of the initiatives’ novel practices, and in relation to the initiative and institutional relations their motivations and expectations. We compare the three cases and discuss how food assistance practices relate to and change (or do not change) the food system. In particular, we elaborate on how these three food assistance initiatives contribute in various ways to local food and welfare system innovation. In doing so, we offer a novel perspective on food assistance initiatives. We argue that they show dynamics that have the potential for more substantial transformation towards food security over time, by building momentum through “small wins”.