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Journal ArticleDOI

Prolonged Parental Care in Royal Terns and Other Birds

01 Jan 1968-The Auk (Oxford Academic)-Vol. 85, Iss: 1, pp 90-100
About: This article is published in The Auk.The article was published on 1968-01-01. It has received 104 citations till now. The article focuses on the topics: Paternal care.
Citations
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Journal ArticleDOI
TL;DR: Juvenile birds differ from conspecific adults in their diet and methods of prey capture and prey handling because of immaturity of the beak, skeleto‐muscular and neurological systems and the time required to learn foraging skills.
Abstract: Summary Juvenile birds differ from conspecific adults in their diet and methods of prey capture and prey handling. Juvenile-adult differences in foraging result from (1) immaturity of the beak, skeleto-muscular and neurological systems and (2) the time required to learn foraging skills. These conclusions are largely based on field observations. More experimental studies to assess the relative importance of the various constraints are needed. Juvenile birds appear to be under strong selection to reach adult form and function as rapidly as possible. Remaining differences between juveniles and adults are largely attributable to constraints. In contrast to many other taxa there are few examples in which juvenile-adult differences in foraging have been accentuated by selection on the juvenile behaviours.

279 citations

Journal ArticleDOI
TL;DR: It is concluded that the difference in breeding success on the two habitats was due to a higher exposure of eggs and chicks to gull predation on level habitat, and that adults on slope habitat were less vulnerable to gull disturbance during incubation and gull robbery when feeding their chicks.
Abstract: Factors contributing to breeding success of puffins were studied on Great Island, Newfoundland, in 1968 and 1969. Puffin burrow density was negatively correlated with distance from the cliff edge and positively correlated with angle of slope. These correlations are biologically significant in that close to the cliff edge, where the angle of slope was steep, breeding success was significantly higher than on adjacent level habitat. In spring both habitats were occupied simultaneously, and nest—site tenacity was equally strong in them. During settlement the frequency of fighting was higher and the peak was reached earlier on slope habitat. Males were heavier on slope than on level habitat just after peak egg laying, although wing lengths were similar. Females were similar on the two habitats. Measurements of eggs from both habitat were the same. Egg—laying dates were also similar, but annual variation was greater on level than on slope habitat, as was variation within a single year. Hatching success was higher on slope habitat, mainly because the incidence of egg disappearance was lower during incubation; also the frequency of infertile eggs was greater on level habitat. Fledging success was higher on slope habitat, and higher on both habitats in 1969. Frequency of chick deaths in the nest and disappearance before fledging was higher on level habitat in both years. Fledging success was higher for early—hatched chicks in both habitats. Total breeding success was higher on slope habitat, and higher in both habitats in 1969. Fledging condition of chicks varied according to the habitat and time period in which they were raised. On the average, body weight at fledging was greater and less variable for birds on slope habitat; early—hatched chicks were heaviest in both habitats. Wing length of young at fledging did not differ. Early—hatched chicks on slope habitat fledged quickest (also quicker than early—hatched chicks on level habitat); late—hatched birds on slope fledged slower than late—hatched birds on level habitat. Age at fledging was greater in 1968 than in 1969 on both habitats. Meal size delivered to chicks by parents was the same on the two habitats, but frequency of feeding was greater on slope than level habitat. Breeding pairs on slope habitat were unable to raise two chicks (artificial twins) to fledging; similarly, one adult could not rear a single chick. Adults feeding chicks on level habitat were attacked and robbed more frequently by gulls than birds on slope habitat, probably because escape (take—off) from an attack was quicker on slope than on level ground. Experiments performed to determine causes of the differential egg and chick loss before fledging in the two habitats showed that during incubation the proportion of eggs displaced to the burrow entrance by incubating birds when leaving the burrow in a hurry was the same, but the rate of panic flights was higher on level habitat. Also, chicks when starved spent more time at the burrow entrance than when fed regularly. It is concluded that the difference in breeding success on the two habitats was due to a higher exposure of eggs and chicks to gull predation on level habitat. The primary cause for this differential exposure was that adults on slope habitat were less vulnerable to gull disturbance during incubation and gull robbery when feeding their chicks. Thus breeding failures resulted from the interactions of food shortage and gull interference. This conclusion was tested by comparing breeding performance of birds at Great Island with birds at two islands where gull interference was absent. Egg and chick survival was greater under "gull—free" conditions. In addition, body weights at fledging were higher and less variable at the colonies without gull interference than at Great Island. The ways in which natural selection acts upon puffins at the breeding colony are considered; a model relating puffin nest distribution and habitat features is presented, and predictions which might be tested are outlined.

218 citations

Book ChapterDOI
TL;DR: This chapter identifies six potential selective costs of learning––namely, delayed reproductive effort and/or success, increased juvenile vulnerability, increased parental investment in each offspring, greater complexity of the central nervous system, greater complex of the genome, and developmental fallibility.
Abstract: Publisher Summary This chapter provides a preliminary account of some of the selective costs and benefits that are involved in the evolution of learning by natural selection. The term “evolution” refers to a change in the population-typical phenotype over some period of time. The aim of a cost-benefit analysis is to allow making statements about the conditions under which particular kinds of adaptations are likely to evolve and explain the reasons for these adaptations being observed in some populations and not in others. Such statements may be either qualitative or quantitative and they may account to a greater or lesser degree for the details of an adaptive trait. The chapter emphasizes on qualitative considerations. It identifies six potential selective costs of learning––namely, delayed reproductive effort and/or success, increased juvenile vulnerability, increased parental investment in each offspring, greater complexity of the central nervous system, greater complexity of the genome, and developmental fallibility.

210 citations

References
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Journal ArticleDOI
28 Jun 2008-Ibis
TL;DR: It is suggested that colonies of tropical oceanic birds deplete the food in the waters round them, and that as the populations increase competition for food becomes more intense, and relatively fewer adults succeed in raising chicks, which would provide a density-dependent control of the output of young and could regulate the numbers of the birds.
Abstract: SUMMARY The ways in which the numbers of tropical sea-birds might be limited are considered; it is argued that food is the only factor likely to be generally effective in limiting numbers, but it seems improbable that food shortage could exert a density-dependent control of the mortality of the birds outside the breeding season. Wynne-Edwards' hypothesis that colonies of sea-birds are able to keep their own numbers below the level at which food shortage would become acute, primarily by exerting control on the output of young, is rejected as unproven and improbable. It is suggested that colonies of tropical oceanic birds deplete the food in the waters round them, and that as the populations increase competition for food becomes more intense, and relatively fewer adults succeed in raising chicks. This would provide a density-dependent control of the output of young and could regulate the numbers of the birds. The peculiarities of long-lived sea-birds (e.g. clutches of one, long fledging periods, deferred maturity) which Wynne-Edwards suggests are adaptations evolved in order to lower the reproductive rate until it balances the mortality, apparently could not be evolved as such; they are more probably adaptations enabling the birds sometimes to raise single chicks in spite of competition for food that makes it impossible to raise more than one. It is considered that variation in the age of first breeding provides an important supplement to variation in reproductive success in regulating the numbers of long-lived tropical sea-birds. The possible applications of this hypothesis to sea-birds breeding in higher latitudes are briefly considered, as are its implications in relation to conservation and exploitation of populations of sea-birds.

803 citations

Book
28 Oct 2017
TL;DR: In this article, the authors discuss the importance of language adaptation in the context of cyber-physical warfare.S (ENGLISH, GERMAN, RUSSIAN) 1
Abstract: S (ENGLISH, GERMAN, RUSSIAN) 1

184 citations

Journal ArticleDOI
01 Jan 1961

180 citations

Journal ArticleDOI
03 Apr 2008-Ibis
TL;DR: The diet of some 20 pairs of Tawny Owls Strix aluco living in woodland is followed and evidence proves them to be strongly territorial and it is suggested that only by having a territory and knowing it intimately can a TawnY Owl survive.
Abstract: Summary. 1. This paper follows over eight years the diet of some 20 pairs of Tawny Owls Strix aluco living in woodland. 2. Pellets were collected regularly and the prey-remains in them were identified. Much information about the territorial and hunting habits of Tawny Owls was gained. 3. There is a regular seasonal swing between small rodents (especially Wood Mice and Bank Voles) and larger prey (young Moles, Rabbits and rats). The former predominate in winter and spring, the latter in summer and autumn. This fluctuation is regular year after year with these animals, whereas shrews and small birds are eaten in small numbers steadily throughout the year and from year to year. 4. Small rodents are eaten most when ground cover is sparsest, which may account for the early breeding season of the Tawny Owl. By the beginning of May, when vegetation is becoming dense and mice and voles are difficult to find, the young are already well-grown and can deal with the food brought to them. The hen is, therefore, free to go hunting herself and both parents must work hard for the next three months while the young are still dependent on them. In more open country Barn and Short-eared Owls seem to time their breeding later so that they are feeding their young on the big crops of Short-tailed Voles and–to a smaller extent–of shrews. 5. This long period of dependence of young Tawny Owls falls when there are plenty of young Moles, often a large crop of cockchafers and generally plenty of earthworms to fall back on. The brownish, fibrous pellets of Tawny Owls are now known to contain mainly the chaetae of earthworms, which are sometimes brought to the young in very large quantities. 6. Analysis of the results by locality shows that Tawny Owls take only the prey species which are available in their immediate vicinity. This and other evidence proves them to be strongly territorial and it is suggested that only by having a territory and knowing it intimately can a Tawny Owl survive.

152 citations

Book
27 Feb 2014

120 citations