Showing papers in "Bird Study in 1985"
TL;DR: The Common Birds Census is designed to measure year-to-year changes in bird population levels, but how representative are the sample plots of the country as a whole?
Abstract: The Common Birds Census is designed to measure year-to-year changes in bird population levels. But how representative are the sample plots of the country as a whole? What is being measured?
57 citations
TL;DR: Since Kestrels digest their food very efficiently (compared to owls), how realistic are the results of kestrel pellet analyses?
Abstract: Since Kestrels digest their food very efficiently (compared to owls), how realistic are the results of Kestrel pellet analyses?
49 citations
TL;DR: In this paper, the authors show that fewer Dippers are present on acidic reaches of rivers, probably because changed water quality affects the birds' food supply, though this is not the only way that watercourses can increase in acidity.
Abstract: There is growing concern amongst conservationists about the consequences of ‘acid rain’, though this is not the only way that watercourses can increase in acidity. This study shows that fewer Dippers are present on acidic reaches of rivers, probably because changed water quality affects the birds' food supply.
48 citations
TL;DR: It is suggested that birds leaving before mid-April were moving to other areas within Britain to build up the fat reserves for the main migration.
Abstract: A study was made of the stability of a population of Turnstones wintering on a rocky shore. Marking birds individually revealed that the majority of Turnstones within the 6 km-long study area were resident from autumn until April or May each year. A greater proportion of juveniles than adults disappeared soon after marking, due either to higher vagility or to mortality. Ninety-five per cent of adult Turnstones resident in the study area at the end of each winter returned the subsequent autumn and the adult annual mortality was estimated to be under 15%. There was little variation between or within years in the numbers of birds present, resulting in a wintering population that was highly stable from year to year. Birds left the study area at an accelerating rate from February to May. The timing of migration of individual Turnstones was consistent from year to year. We suggest that birds leaving before mid-April were moving to other areas within Britain to build up the fat reserves for the main migration.
47 citations
TL;DR: Differences in the breeding success of Reed Warblers in wet versus dry sites seemed to be linked more with levels of nest predation than with variations in food availability.
Abstract: Differences in the breeding success of Reed Warblers in wet versus dry sites seemed to be linked more with levels of nest predation than with variations in food availability.
42 citations
TL;DR: It has been asserted previously that spring counts of drumming Snipe over-estimate breeding population size, but the present study reveals that the reverse is true.
Abstract: It has been asserted previously that spring counts of drumming Snipe over-estimate breeding population size. Yet the present study reveals that the reverse is true.
36 citations
TL;DR: In this article, 14 radio transmitters were attached to Guillemots on the Isle of May in 1983 and 1984, and the birds retained their transmitters for 10-20 days.
Abstract: In 1983–84, 14 radio transmitters were attached to Guillemots on the Isle of May. Those with internal tuned loop transmitting aerials, glued in the centre of the bird's back with a small amount of resin were most satisfactory. Most birds retained their transmitters for 10–20 days. The bird's behaviour was sometimes altered and ways of minimizing this are discussed. Except when they had young, three (apparently normal) breeding Guillemots spent very little time on the sea in front of their site. The maximum foraging range was smallest at this time.
36 citations
TL;DR: The extent of dietary overlap between the four species studied was more significant than any differences between them; but, in practice, competition between them will have been reduced by the way they hunted over different habitats.
Abstract: The extent of dietary overlap between the four species studied was more significant than any differences between them; but, in practice, competition between them will have been reduced by the way they hunted over different habitats.
35 citations
TL;DR: Bird-plant interactions are not so well known as they ought to be, but nectar is a potential food source to birds, while the plants could benefit also from having the birds act as pollinators.
Abstract: Bird-plant interactions are not so well known as they ought to be. Nectar is a potential food source to birds, while the plants could benefit also from having the birds act as pollinators.
35 citations
TL;DR: In East Anglia in 1983–84, Marsh Harriers preyed upon most species of birds and mammals present in their hunting areas, and small birds, young gamebirds and waterbirds and mammals formed 90-95% of the diet by numbers and weight.
Abstract: In East Anglia in 1983–84, Marsh Harriers preyed upon most species of birds and mammals present in their hunting areas. Small birds, young gamebirds and waterbirds and mammals formed 90-95% of the diet by numbers and weight. Small adult birds and mammals were important in April-May, but thereafter young gamebirds and waterbirds formed an increasing proportion of the diet, whilst the proportion of mammals declined. Females and polygynous males took larger prey after the young had hatched than did monogynous males. There was no difference in the proportions of large prey taken by polygynous males and the much larger females. There was some evidence of a difference in diet for monogynous males, in the latter part of the season, when they took fewer mammals and more small birds. Polygynous males took larger prey later in the season, mainly by taking larger individuals of the same species. There was no evidence that the proportion of large prey brought by males to individual nests was linked to brood size.
24 citations
TL;DR: Although born in coniferous forest, the birds spent most time in scrubland, deciduous woodland and farmland, and moved in any direction away from their birthplace with a maximum distance ranging 4–22 km.
Abstract: Eight nestling Sparrowhawks in Northamptonshire were marked with radiotransmitters to determine fledging and dispersal dates and the distances and directions travelled away from the nest. One male left the nest at 26 days old and dispersed 28 days later. Females fledged at 28–30 days old and dispersed 25–27 days later. The birds moved in any direction away from their birthplace with a maximum distance ranging 4–22 km. Although born in coniferous forest, the birds spent most time in scrubland, deciduous woodland and farmland.
TL;DR: The overall pattern of counts made at sea reflects the well-known seasonal movements of Gannets as discussed by the authors, and fishing trips rarely exceed 150 km from colony and most are below one-third of that distance.
Abstract: The overall pattern of counts made at sea reflects the well-known seasonal movements of Gannets. During the breeding season, fishing trips rarely exceed 150 km from colony and most are below one-third of that distance.
TL;DR: The diurnal rhythm of colony attendance by Black Guillemots varied seasonally as mentioned in this paper and the number of adults associated with breeding habitat accounts for most birds occupying suitable nest sites and censuses in northern Britain should be conducted in this period.
Abstract: The diurnal rhythm of colony attendance by Black Guillemots varied seasonally. No tidal effects were detected but in April attendance was lower when winds exceeded force 4. Numbers were most stable during 05.00–08.00 GMT in the pre-breeding period. Counts at this time and in winds of force 4 or less provide the best estimate of adult populations. Between late March and mid-May, counts of adults associated with breeding habitat account for most birds occupying suitable nest sites and censuses in northern Britain should be conducted in this period. As the proportion of non-breeding adults varies between colonies, no universal correction factor can be used to estimate the number of breeding attempts from counts of birds. Counts aimed at detecting maximum attendance provide greater accuracy than single counts made by flushing all birds on to the sea but take longer. Monitoring units should be stretches o-f coastline that include a number of colonies of different sizes.
TL;DR: The mean size of 222 clutches in Dippers breeding in the southern catchment of the Welsh River Wye between 1978 and 1983 was found to be significantly larger than values given by all other studies in Britain where data were sufficient for statistical comparison.
Abstract: Laying dates, clutch and brood size, and the incidence of double brooding, in Dippers breeding in the southern catchment of the Welsh River Wye between 1978 and 1983 are described and compared with data from other regions of Britain and mainland Europe. The mean size of 222 clutches (4.78±0.08) was found to be significantly larger than values given by all other studies in Britain where data were sufficient for statistical comparison. This is discussed in relation to territory quality and other influences.
TL;DR: The hiding (caching) of food by crows is well known as mentioned in this paper. But how much of this is recovered later, and are caches relocated by memory or through chance rediscovery?
Abstract: The hiding (caching) of food by crows is well known. But how much of this is recovered later, and are caches relocated by memory or through chance rediscovery?
TL;DR: In this article, it was shown that there is considerable regional variation in the mobility of Herring Gulls in the British Isles and that long distance movement is more frequent in birds reared in the north of Britain.
Abstract: This analysis shows that there is considerable regional variation in the mobility of Herring Gulls in the British Isles, and that long distance movement is more frequent in birds reared in the north of Britain.
TL;DR: Black Guillemots populations are much larger than was previously thought, largely due to improved census methods and coverage, and breeding was widespread with most colonies comprising fewer than 20 birds.
Abstract: Surveys of adult Black Guillemots associated with breeding habitat in the pre-breeding period recorded totals of 6883 in Orkney and 12,008 in Shetland. These populations are much larger than was previously thought, largely due to improved census methods and coverage. Although the distribution of suitable sites influenced the distribution of nests, breeding was widespread with most colonies comprising fewer than 20 birds. Nest sites accessible to ground predators were used on islands free from Brown Rats or Stoats but on infested islands Black Guillemots bred only in higher cliffs. The lowest breeding densities were in Yell Sound and it is likely that the population there was still recovering from the effects of a large oil spill.
TL;DR: When censusing breeding waders in large upland areas, the time of day has a major influence on the numbers of birds detected.
Abstract: When censusing breeding waders in large upland areas, the time of day has a major influence on the numbers of birds detected.
TL;DR: This 7982 enquiry confirmed that the long-term Cirl Bunting decline is continuing, with the species becoming increasingly concentrated in Devon (78% of registrations).
Abstract: This 7982 enquiry confirmed that the long-term Cirl Bunting decline is continuing, with the species becoming increasingly concentrated in Devon (78% of registrations). Possible reasons for the trend are discussed.
TL;DR: Flies (Diptera) were found to be more important prey items than had been expected, and possibly they are captured when torpid in low temperatures, as in early mornings.
Abstract: Flies (Diptera) were found to be more important prey items than had been expected Possibly they are captured when torpid in low temperatures, as in early mornings
TL;DR: After declining during the 1960s and 1970s, there has been some recovery in numbers of Rook nests in recent years as mentioned in this paper, but numbers of active rookeries have continued to fall, so that more nests are concentrated into fewer colonies.
Abstract: After declining during the 1960s and 1970s, there has been some recovery in numbers of Rook nests in recent years. In contrast, numbers of active rookeries have continued to fall, so that more nests are concentrated into fewer colonies.
TL;DR: The view has been expressed that numbers of migrants alighting at coastal bird observatories do not reflect the scale of migration passing overhead, but is this always the case?
Abstract: The view has been expressed that numbers of migrants alighting at coastal bird observatories do not reflect the scale of migration passing overhead. But is this always the case?
TL;DR: Observations revealed that these two gull species were exploiting fields in different ways, with Common Gulls feeding more on pasture, and perhaps gulls ‘decide’ whether to use a site through balancing its food resources against the numbers of gulls already feeding there.
Abstract: Observations revealed that these two gull species were exploiting fields in different ways, with Common Gulls feeding more on pasture. There were also age-related differences. Perhaps gulls ‘decide’ whether to use a site through balancing its food resources against the numbers of gulls already feeding there.
TL;DR: There were about 54,300 occupied nests in Shetland in 1981, and no evidence that any marked population change was occurring.
Abstract: There were about 54,300 occupied nests in Shetland in 1981, and no evidence that any marked population change was occurring. Distribution of colonies showed clear correlation with rock type.
TL;DR: In Nottinghamshire, Canada Goose numbers have increased in Nottinghamshire to a point where conflict has arisen with agricultural interests as discussed by the authors, leading to the creation of a Canada Goose Protection Association.
Abstract: As elsewhere in England, Canada Goose numbers have increased in Nottinghamshire to a point where conflict has arisen with agricultural interests.
TL;DR: Detailed examination of the recovery of the Sparrowhawk in Sussex suggests that the pattern was atypical of Britain as a whole, and DDT should be regarded as responsible for the destruction of the Kent Sparrowhawk population.
Abstract: Detailed examination of the recovery of the Sparrowhawk in Sussex suggests that the pattern was atypical of Britain as a whole. This can be linked to an unusual agricultural pattern in Surrey, Sussex and Kent, where the percentage of tillage is low for eastern lowland England, with exceptionally high areas of orchards in Kent. This influenced the use of organo-chlorine pesticides, with cyclodienes (aldrin and dieldrin) little used on tillage crops after 1962 but DDT used heavily in orchards until the mid-1970s. The recovery of Sparrowhawks in Sussex and Kent reflected this usage, with a rapid partial recovery following the restriction of cyclodiene use after 1962, followed by a much steeper recovery from the mid-1970s, associated with greatly improved breeding performance following the major reduction in DDT use. DDT should be regarded as responsible for the destruction of the Kent Sparrowhawk population and probably depressed that of Sussex to well below half its pre-1945 level in terms of regular breedi...