The influence of human and goshawk Accipiter gentilis activity on wood-pigeons Columba palumbus at brassica feeding sites

Humans caused more than half the disturbance of wood-pigeons, Columba palumbus, from roadside brassica feeding sites. The birds always flew away from pedestrians, cyclists and horsemen, but often remained feeding when closed vehicles passed. The pigeons resettled immediately on the same feeding site after 23% of goshawk, Accipiter gentilis, attacks, and birds were feeding there later the same day after nearly half the attacks. They resettled immediately after a similar proportion (19%) of the times they were approached by humans on foot, and rarely fed in fields where people were working. The shorter the time pigeons had spent feeding before an interruption, the sooner they returned after it. This probably reflected the level of their crop food reserves. This behaviour should minimise the effect of short duration disturbance, as caused by goshawk attacks, on wood-pigeons feeding at brassica sites. Goshawk attacks did not cause a reduction in pigeon pecking-rate. Pigeons feeding in roadside fields tended to avoid the side nearest to the road, but not parts of fields adjoining walls and hedges which could have provided cover for predatory attacks. It is concluded that scaring techniques based on man himself are more promising than use of the goshawk in protecting crops against wood-pigeons.     

Breeding ecology of a suburban population of Woodpigeons Columba palumbus in northwest England

Capsule Between 1981 and 2008 population size was stable, but there were negative trends in breeding parameters.

Aims To determine the current status and long‐term population trend of an isolated breeding population of Bearded Vultures Gypaetus barbatus (Corsica, Mediterranean).

Methods The total Bearded Vulture population was monitored between 1981 and 2008.

Results The current effective breeding population size of Bearded Vultures in Corsica is ten pairs/trios with a slight increase of one to two pairs since 1983. The population is currently estimated at 25 individuals. Breeding parameters (laying rate, breeding success and productivity) have decreased significantly over the full 28‐year study period, although the decrease was not significant when the data set was restricted to 1988–2008. A mean of 60.3% (n = 204) of pairs have laid, but this proportion is highly variable between years. Productivity has been very low (0.16 young/pair/year, n = 233). Breeding parameters of the Corsican population of Bearded Vultures are very low compared with those of other western European populations in the Pyrenees.

Conclusions This isolated insular population is of small size (eight to ten pairs/trios) but shows a stability of distribution and numbers, but low (and decreasing) breeding rates, making this insular population one the most threatened in Europe.     

The effects of changing agricultural practice upon Woodpigeon Columba palumbus numbers

The Woodpigeon Columba palumbus population in a 1070 ha study area in East Anglia was studied from 1961 to 1986. This paper relates variations in Woodpigeon numbers to changes in the areas and types of crops grown. In the early 1960s the mean Woodpigeon population fluctuated between 60 and 112 birds per 50 ha during the winter months. Subsequently there was a steady decline until the population levelled out in the early 1970s at around 30 birds per 50 ha. From a very low point in 1977, the numbers of birds increased reaching in 1986 a mean of 55 birds per 50 ha. Marked changes occurred in the types of cereals grown in the area. In the 1960s spring-sown barley was the major crop with winter-sown wheat occupying most of the remaining area. Throughout the 1970s winter wheat was increasingly grown and winter-sown barley replaced the spring-sown variety. Although the area of permanent pasture did not change significantly, the area of clover ley was reduced markedly in the late 1960s. In the mid 1970s silage and oilseed rape were introduced and the cultivation of peas was expanded. On the basis of the crop types grown, the study period was divided into two 11-year blocks 1961–1971 and 1975–1985. Crop preferences of Woodpigeons were calculated for each month within each of these 11-year periods. A series of stepwise regressions was then conducted on both of the 11-year periods in order to see how well the areas of preferred crops in a particular month could account for the mean population size of that month. In the winters 1961/62 to 1971/72 the winter Woodpigeon population size was influenced by two crops. The area of cereal sowings largely determined how many birds remained in the area in December. The availability of clover ley, which depended upon both the area of clover ley and the amount of snow cover, controlled the population size in January and February. In the winters 1975/76 to 1985/86 the population size was again affected by two crops. In November the amount of grain on both stubbles and sowings influenced how many young birds stayed in the area. The area of oilseed rape in December then set the population size which changed very little throughout the rest of the winter. The change in the pattern of population regulation has profound implications for the likely success of shooting Woodpigeons in winter as a means of reducing local numbers.     

The Host-Restriction of Haemoproteus sp. indet. of the Wood-Pigeon Columba p. palumbus

SYNOPSIS. Earlier experiments suggested that the species of Haemoproteus which infects English wood-pigeons ( Columba p. palumbus ) and is transmitted by the hippoboscid dipteran fly Ornithomya avicularia , was unable to infect Columba livia domestica , a host of H. columbae . This has now been confirmed by the injection of sporozoites into two pairs of pigeons, one of each species; in both experiments the C. palubus developed parasitemia while the C. livia did not. It has also been shown that this species of Haemoproteus can complete sporogony in a small proportion (2/73) of Pseudolynchla canariensis , the vector of H. columbae .     

Nest survival of Woodpigeons (Columba palumbus) in North African forests

Capsule The nesting success of the Woodpigeon Columba palumbus in oak forests in Morocco is affected by human disturbance and nest-site characteristics.

Aims To determine factors affecting the nesting success of Woodpigeons subject to two levels of disturbance in a holm oak Middle Atlas forest.

Methods Woodpigeon nests were monitored in highly disturbed (n?=?30) and less-disturbed sites (n?=?60) over two years (2010–11). Logistic-exposure models were used to estimate daily nest-survival rate and evaluate mechanisms (altitude, temporal factors, nest location, nest-site habitat and degree of human influence) affecting nest survival.

Results Daily nest-survival rate was higher in less-disturbed sites (0.987; 95% CL: 0.980–0.991) than in high-disturbance sites (0.967; 95% CL: 0.949–0.978). Increasing density of trees surrounding nest sites and distance from the nest tree to the closest track increased daily nest-survival rate.

Conclusions Less-disturbed sites confer better nesting conditions than highly disturbed ones. Management measures should control the access of vehicles, especially trucks, in the forest of the Middle Atlas and introduce a grazing regime that will allow the forest regeneration, which would improve Woodpigeon nesting success by increasing the density of holm oak trees.     

Seasonal variation in the diet and food preference of the Woodpigeon Columba palumbus in Ireland

Capsule The Woodpigeon Columba palumbus has a wide and varied diet, dominated by vegetable matter. This study found no significant difference in the diet of male and female birds in North-East Ireland; however, diet differed significantly between the seasons. In summer and autumn, the grains of cereal crops constituted the largest proportion of the diet, whereas in spring and winter, diet was dominated by the fruit and seeds of trees. This varied diet allows Woodpigeons to feed on seasonally abundant food sources, that have a high calorific content and that are ignored by most other seed-eating birds.     

Long term changes in the breeding biology of the woodpigeon Columba palumbus in eastern England

Changes in agricultural practice in eastern England have been shown to have had marked effects upon the winter population size of the woodpigeon Columba palumbus This study examines whether changes in the breeding success of the woodpigeon have also occurred Data were gathered between 1962 and 1983 on the breeding activities of woodpigeons within a wood near Newmarket in eastern England The number of nests monitored each year varied between 16 and 122 with a mean of 45 Agricultural changes resulted in a steep decline in the winter population size in the late 1960's and the breeding population snowed a similar fall Before this decline, productivity was on average 2 8 young per pair, but afterwards it was only 1 8 young per pair This drop in productivity resulted from greater egg predation, which increased steadily over the study period Increased egg predation and variation in seasonal patterns of breeding behaviour are discussed in relation to likely predator numbers and changes in both agricultural and shooting practices In the 1960 s. overwinter starvation was the major limiting factor on the woodpigeon population, but after the mid-1970's low productivity has increasingly become the most important factor     

Ethics,ecology and economics

This paper describes the general structure of an environmental philosophy. There can be many such philosophies, and those with their roots in economic theory have been extensively studied recently. Specific examples cited in the paper include the work of David Pearce and Robert Goodin. Economics-based philosophies can founder on the issue of externalities and a misplaced attempt to provide a comprehensive approach to valuing nature as a bundle of goods and services. It is argued that it is dangerously easy to slide from considering nature as a standing reserve of processes and objects that have the potential to satisfy human desires to the idea that it is nothing more than that. In general, the consequentialist basis of economics limits its usefulness in contributing to informed environmental decisions. But there is room for a sensitive use of institutional environmental economics as a partial guide for our reflections and choices. Any such development should take on board the existence of a plurality of perspectives on fundamental issues and the pluralism of values that can be found within moral theory itself.     

Factors affecting reproduction of Woodpigeons Columba palumbus in North African forests: 1. Nest habitat selection

Capsule Woodpigeon Columba palumbus nest-tree selection is affected by human disturbance, grazing and tree characteristics.

Aims To determine the characteristics of trees used for nesting by Woodpigeons under two levels of grazing and disturbance in a Holm oak Middle Atlas forest, Morocco.

Methods Woodpigeon nest-tree selection was investigated in highly disturbed and less-disturbed sites over two years (2010 and 2011). The features of nest-tree characteristics were determined by comparing the characteristics of trees used for nesting to those of randomly selected trees.

Results Tree physical characteristics, grazing intensity and level of human disturbance were the main factors determining selection for nest-trees. Woodpigeons chose nesting trees that were greater in height, larger in DBH, lower in base of the live crown, in denser stands and at greater distance from tracks.

Conclusions Forest management for Woodpigeon nest habitat selection should focus on controlling the access of vehicles especially trucks, introducing a rotating system of forest utilization for grazing and maintaining (without extending) the cereal crops. These recommendations may assist land managers to plan for continued persistence of this species in Middle Atlas forests.     

Haemoproteus palumbis sp. nov. (Sporozoa, Haemosporina) of the English Wood-Pigeon Columba p. palumbus

SYNOPSIS. Haemoproteus palumbis sp. nov. is described from the English wood-pigeon, Columba p. palumbus. Its pigmented gametocytes inhabit erythrocytes and resemble those of H. columbae (in C. livia ) but may be slightly longer and narrower. It is characterized by having oval or slightly lobed, not elongate, schizonts in endothelial cells of lung and heart, a prepatent period of 14 days, and a sporogonic cycle in the hippoboscid fly Ornithomya avicularia lasting 6 1/2–7 days. H. palumbis sp. nov. cannot infect C. livia but can infect a small proportion of individuals of Pseudolynchia canariensis , the vector of H. columbae.