Sex Roles in the American Oystercatcher

Behaviour ◽  
1985 ◽  
Vol 95 (3-4) ◽  
pp. 232-260 ◽  
Author(s):  
Erica Nol
Keyword(s):  
Energy Expenditure ◽  
Parental Care ◽  
Breeding Season ◽  
Sex Roles ◽  
Breeding Stage ◽  
American Oystercatcher ◽  
Males And Females

AbstractAmerican oystercatchers have extensive parental care. As a result sex roles are similar and highly complementary. During the pre-laying period the roles of males and females, except during copulation, are indistinguishable. During the laying period the roles diverge slightly with males spending more time chasing conspecifics. Presumably the similarity during pre-laying, and the differences during laying, function to prevent the male from being cuckolded. Males begin assisting in incubation as soon as the females begin incubating and then consistently perform the same proportion of incubation throughout this breeding stage. During incubation, females incubate more often than males, and consequently rest less, preen less and fly less than males. During chick-rearing males are involved in more chases than females and take more foraging trips to provision young but wait longer between successive trips. The pattern of foraging by each sex is complementary. Breeding season energy expenditure is approximately equal in both sexes. There is no evidence for conflict between the sexes over the contributions to parental care. Where sex roles diverge the differences in behaviour can be partly explained by the relative energetic efficiencies of each sex performing different tasks.

scholarly journals Tri-axial accelerometry shows differences in energy expenditure and parental effort throughout the breeding season in long-lived raptors

2021 ◽  
Author(s):  
Pascual LÓPEZ-LÓPEZ ◽  
Arturo M PERONA ◽  
Olga EGEA-CASAS ◽  
Jon ETXEBARRIA MORANT ◽  
Vicente URIOS
Keyword(s):  
Energy Expenditure ◽  
Parental Care ◽  
Breeding Season ◽  
Video Recording ◽  
Experimental Manipulation ◽  
Biparental Care ◽  
Breeding Ecology ◽  
Parental Effort ◽  
Ecological Data ◽  
Movement Trajectories

Abstract Cutting-edge technologies are extremely useful to develop new workflows in studying ecological data, particularly to understand animal behaviour and movement trajectories at the individual level. Although parental care is a well-studied phenomenon, most studies have been focused on direct observational or video recording data, as well as experimental manipulation. Therefore, what happens out of our sight still remains unknown. Using high-frequency GPS/GSM dataloggers and tri-axial accelerometers we monitored 25 Bonelli’s eagles (Aquila fasciata) during the breeding season to understand parental activities from a broader perspective. We used recursive data, measured as number of visits and residence time, to reveal nest attendance patterns of biparental care with role specialization between sexes. Accelerometry data interpreted as the Overall Dynamic Body Acceleration, a proxy of energy expenditure, showed strong differences in parental effort throughout the breeding season and between sexes. Thereby, males increased substantially their energetic requirements, due to the increased workload, while females spent most of the time on the nest. Furthermore, during critical phases of the breeding season, a low percentage of suitable hunting spots in eagles’ territories led them to increase their ranging behaviour in order to find food, with important consequences in energy consumption and mortality risk. Our results highlight the crucial role of males in raptor species exhibiting biparental care. Finally, we exemplify how biologging technologies are an adequate and objective method to study parental care in raptors as well as to get deeper insight into breeding ecology of birds in general.

Energy Expenditure in Reproductive Effort of Male and Female Killdeer (Charadrius vociferus)

The Auk ◽  
1988 ◽  
Vol 105 (3) ◽  
pp. 553-564 ◽  
Author(s):  
Dianne H. Brunton
Keyword(s):  
Reproductive Success ◽  
Energy Expenditure ◽  
Parental Care ◽  
Breeding Season ◽  
Reproductive Effort ◽  
Mating Effort ◽  
Parental Effort ◽  
Nest Failure ◽  
Male And Female ◽  
Charadrius Vociferus

Abstract The reproductive investment strategies of the sexes during the breeding season are detailed for Killdeer (Charadrius vociferus), a monogamous plover. I measured the energy investments of the sexes in reproductive, mating, and parental effort. As predicted, males expend more mating effort than females; however, the sexes expend equal amounts of parental effort. Total energy expenditure in reproductive effort (mating and parental effort) during a successful nesting attempt was also equal for the sexes. However, early parental effort expenditures by females, early mating effort expenditures by males, and high rates of nest failure combine to result in female reproductive energy expenditures being significantly higher over the breeding season. This suggests that energy expenditure alone is not adequate for accurate comparisons of the relative investments of the sexes. Studies investigating male and female investments need to consider the degree and pattern of nest failures along with patterns of energy expenditure. The advantages to male and female Killdeer of sharing parental care is demonstrated using adult removal experiments. In general, a deserted parent expends more energy in parental effort than a bi-parental parent and has significantly lower reproductive success. However, males are able to hatch chicks, whereas females lose or abandon their nests within a few days of mate removal. Thus, monogamy in Killdeer appears to result from high nest failure rates, the necessity of two parents for any reproductive success, and the generalizable nature of Killdeer parental care.

scholarly journals Degree of anisogamy is unrelated to the intensity of sexual selection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Judit Mokos ◽  
István Scheuring ◽  
András Liker ◽  
Robert P. Freckleton ◽  
Tamás Székely
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Life History ◽  
Parental Care ◽  
Sex Roles ◽  
Sexual Size Dimorphism ◽  
Ecological Factors ◽  
Size Dimorphism ◽  
Wide Range ◽  
Males And Females

AbstractMales and females often display different behaviours and, in the context of reproduction, these behaviours are labelled sex roles. The Darwin–Bateman paradigm argues that the root of these differences is anisogamy (i.e., differences in size and/or function of gametes between the sexes) that leads to biased sexual selection, and sex differences in parental care and body size. This evolutionary cascade, however, is contentious since some of the underpinning assumptions have been questioned. Here we investigate the relationships between anisogamy, sexual size dimorphism, sex difference in parental care and intensity of sexual selection using phylogenetic comparative analyses of 64 species from a wide range of animal taxa. The results question the first step of the Darwin–Bateman paradigm, as the extent of anisogamy does not appear to predict the intensity of sexual selection. The only significant predictor of sexual selection is the relative inputs of males and females into the care of offspring. We propose that ecological factors, life-history and demography have more substantial impacts on contemporary sex roles than the differences of gametic investments between the sexes.

Observation on the breeding biology of Polypedates teraiensis (Dubois, 1987) (Amphibia: Rhacophoridae)

2017 ◽  
Vol 17 (1) ◽  
pp. 25-32
Author(s):  
Jacinta Lalchhanhimi ◽  
Lalremsanga H.T.
Keyword(s):  
Sexual Dimorphism ◽  
Breeding Season ◽  
Sound Production ◽  
Reproductive Function ◽  
Breeding Biology ◽  
Tree Frog ◽  
University Campus ◽  
Morphometric Measurements ◽  
Advertisement Calls ◽  
Males And Females

The breeding biology of tree frog, Polypedates teraiensis was studied during the breeding season at Mizoram University Campus. It was found that sound production by male during the breeding season was primarily a reproductive function and advertisement calls attract females to the breeding areas and announce other males that a given territory is occupied. The aim of this study was to provide the detailed information on the breeding behaviour and the advertisement calls of Polypedates teraiensis. The morphometric measurements of the amplecting pairs (males and females) for sexual dimorphism along with clutch sizes were also studied.

scholarly journals Offspring and adult chemosensory recognition by an amphisbaenian reptile may allow maintaining familiar links in the fossorial environment

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10780
Author(s):  
José Martín ◽  
Ernesto Raya-García ◽  
Jesús Ortega ◽  
Pilar López
Keyword(s):  
Parental Care ◽  
Chemical Cues ◽  
Kin Recognition ◽  
Social Groups ◽  
Tongue Flick ◽  
Adult Males ◽  
Stable Family ◽  
Males And Females ◽  
Family Groups

Kin recognition is a phenomenon with an important function in maintaining cohesive social groups in animals. Several studies have examined parent–offspring recognition in species with direct parental care. Few studies have, however, explored parent–offspring recognition in animals that, at best, only show apparent indirect parental care, such as some reptiles. In this study, we investigated reciprocal parent–offspring recognition in the fossorial amphisbaenian Trogonophis wiegmanni, a viviparous species that shows potential stable ‘family groups’ in the form of parent-offspring long-term associations. We examined whether adult males and females could discriminate via chemical cues between familiar juveniles which associate with them within their family groups, and are potentially their offspring, to that of unfamiliar juveniles, and whether juveniles could discriminate between familiar adult males and females of their family group (probably their parents) and unfamiliar unrelated adults. We measured tongue flick behavior to study chemosensory responses to the scent of conspecifics. We found that adult female amphisbaenians, but not males, could discriminate between scents of familiar and unfamiliar juveniles. Juvenile amphisbaenians did not discriminate between familiar and unfamiliar adult females, but recognize familiar from unfamiliar males. We discuss our results of parent–offspring recognition according to its potential social function in an ecological fossorial context where visibility is limited and chemosensory kin recognition may contribute to the establishment of stable family groups.

4. Sex roles and stereotypes

2018 ◽  
pp. 52-68
Author(s):  
Leigh W. Simmons
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sexual Behaviour ◽  
Sex Roles ◽  
Animal Species ◽  
Male And Female ◽  
Mating Competition ◽  
Characteristic Behaviour ◽  
Males And Females ◽  
Female Roles

‘Sex roles and stereotypes’ examines the notion, implicit in many of the original ideas about sexual selection, that males and females have natural ‘roles’ with characteristic behaviour associated with each sex. It also explores further the reasons behind deviations from the ‘typical’ sex roles in mate choice and in mating competition. Are there ‘standard’ male and female roles in both humans and other animal species? One version of sex roles holds that males are generally dominant and females submissive, stemming from the way that sexual selection favours different behaviours in each sex. This could mean that sexual selection dictates particular behaviours in males and females. But in fact, sexual behaviour is extraordinarily varied in nature.

2. Mating systems, or who goes with whom, and for how long

2018 ◽  
pp. 16-33
Author(s):  
Leigh W. Simmons
Keyword(s):  
Sexual Selection ◽  
Mating System ◽  
Social Relationships ◽  
Breeding Season ◽  
Mating Systems ◽  
Practical Applications ◽  
Multiple Partners ◽  
Monogamous Species ◽  
Genetic Techniques ◽  
Males And Females

‘Mating systems, or who goes with whom, and for how long’ examines the variation in how males and females associate during the breeding season, ranging from brief couplings with multiple partners to lifelong monogamy. It also shows how the discovery that females mate with many partners, even in supposedly monogamous species such as songbirds, was made possible by modern genetic techniques. Variation in mating systems holds considerable implications for the operation of sexual selection. The way that animal mating systems have been explained historically is outlined before considering how a more contemporary understanding of genetic and social relationships has reshaped our thinking and how understanding a species’ mating system can have practical applications.

Sex-biased parental-care allocation in three tern species (Laridae, Aves)

1995 ◽  
Vol 73 (8) ◽  
pp. 1461-1467 ◽  
Author(s):  
Mauro Fasola ◽  
Nicola Saino
Keyword(s):  
Parental Care ◽  
Agonistic Behavior ◽  
Sexual Size Dimorphism ◽  
Reproductive Effort ◽  
Seabird Species ◽  
Theoretical Predictions ◽  
Males And Females ◽  
Sandwich Tern ◽  
Parental Expenditure ◽  
Care Allocation

We studied parental-care allocation by males and females in three tern species. Female Common Terns (Sterna hirundo) and Little Terns (S. albifrons) performed more incubation and brooding than males, whereas in the Sandwich Tern (S. sandvicensis) the sexes shared these duties equally. In all three species, agonistic behaviors were performed equally by females and males. Prey types brought by males and females of each species were similar, but males tended to bring larger prey and had higher delivery rates than females. Information on parental-care allocation by female and male seabirds of various species, 5 gulls, 6 terns, and 1 skimmer, indicates that females perform most of the incubation and brooding in both gulls and terns, whereas males perform most territory attendance and agonistic behavior (gulls) and more prey provisioning (terns). These patterns are qualitatively consistent with the explanation that the differences between gulls and terns in sex-biased parental care are related to the fact that gulls exhibit sexual size dimorphism but terns do not. Contrary to theoretical predictions that in monogamous birds, females contribute more reproductive effort than males, in all the seabird species studied so far the total parental expenditure by males seems to equal or outweigh that by females.

Division of parental duties confirms a need for bi-parental care in a precocial bird, the mute swan Cygnus olor

2015 ◽  
Vol 65 (2) ◽  
pp. 163-176 ◽  
Author(s):  
Radosław Włodarczyk ◽  
Piotr Minias
Keyword(s):  
Parental Care ◽  
Breeding Season ◽  
Time Budget ◽  
Empirical Support ◽  
European Population ◽  
Mute Swan ◽  
Cygnus Olor ◽  
Territory Defence ◽  
Male Activity ◽  
Reproductive Activities

Parental investment is much reduced in precocial species when compared with altricial species, which may explain a predominance of uni-parental care in this group of birds. In precocial wildfowl, bi-parental care is mostly restricted to arctic-breeding species, where the short reproductive season forces mates to cooperate in caring for the young, but a temperate breeding mute swan Cygnus olor is one of the few notable exceptions. In order to explain a need for bi-parental care in this species, we collected data on the time-budget of eleven swan breeding pairs from a Central European population. We found sex-related differences in the mean time allocated to incubation, movement, feeding, resting and aggression. Others behaviours (nest maintenance, alert and comfort) changed along the breeding season, but did not differ between sexes. Females were primarily responsible for providing care to the brood, whereas male activity focused on territory defence and family guarding. Females were exclusively responsible for incubation and they covered 85% of the total time allocated by parents to feeding cygnets. Nearly constant incubation in females limited possibilities for other activities, including foraging. Males allocated significantly more time than females to aggressive interactions, directed mainly towards other breeding pairs and non-breeders. A clear division of parental duties between sexes gave empirical support for the presence of bi-parental care in the mute swan, despite the fact that reproductive activities of this species are not constrained by the short length of the breeding season, as in arctic-breeding wildfowl.

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