First record of the fledging period of Temminck's Courser,Cursorius temminckii

The Seychelles Fody, Foudia sechellarum, is a ploceid weaver occurring naturally on three islands in the Seychelles group in the Indian Ocean. The population on Cousine Island was studied between 30 June and 25 August 1997. The size of the population on the island was estimated at 458–614 individuals and densities varied in different habitat types. As Seychelles Fodies in non-breeding plumage are difficult to sex, we provide sexing criteria based on wing length. Breeding pairs form small, probably temporary, territories that are defended by both partners against other fodies, including the introduced Madagascar Fody, Foudia madagascariensis. The Seychelles Fody often breeds semi-colonially and we observed up to five nests close together. The birds are socially monogamous and both sexes share in nest building, nest defense and provisioning of the young. Only females incubate. Many nests were deserted before eggs were laid, including some that had been accepted by the female. Additional males and females were sometimes seen helping provision the young, but this cooperative breeding behaviour appeared to be uncommon. Non-breeding individuals congregate in large flocks, sometimes joined by breeding birds.     

A TWELVE-MONTH FIELD STUDY OF THE ALDABRAN FODY FOUDIA EMINENTISSIMA ALDABRANA

The Aldabran Fody Foudia eminentissima aldabrana was studied for 12 months on West Island, Aldabra atoll. A complete annual cycle was followed in detail in a small population of marked birds, and observations were made on feeding, courtship, breeding and other behaviour. The breeding season coincided closely with the wet season, when insect abundance was highest.
Although coconut palms and casuarina trees are both thought to have been introduced into Aldabra by man, the fodies preferred both of these trees as nest-sites to the native vegetation. It is suggested that this may be a recent preference, resulting from excessive predation by introduced rats Rattas rattus on nests in other sites.
In addition to insects and seeds, the Aldabran Fody feeds partly on nectar, and its tongue shows some degree of adaptation to a nectar diet. It is argued that the diversity in bill shape in Foudia cannot be interpreted simply in terms of adaptation for feeding on insects or seeds, but that all three elements in the diet must be considered, in conjunction with the presence or absence of possible competitors.
Adult males defend and maintain nesting territories for most of the year. After breeding, they undergo a full moult and assume an eclipse (female-type) plumage for a variable length of time, regaining the male breeding plumage after a partial prenuptial moult. A small number of males were found to be aberrant, the red in the plumage being replaced by golden yellow. One such bird showed defective territorial behaviour, and four that were dissected Jacked gonads.
In almost all ways the behaviour and reproductive patterns of the Aldabran Fody are very similar to those of the Madagascar Fody F. madagascariensis. The latter has been introduced onto many Indian Ocean islands, and in view of its similarities to the Aldabran Fody might well be a serious competitor if it were to be introduced onto Aldabra.     

Reproductive success and survivorship of the Galapagos Hawk Buteo galapagoensis: potential costs and benefits of cooperative polyandry

The Galapagos Hawk Buteo galapagoensis is one of few species showing cooperative polyandry. As many as four males may mate with one female and share a territory and nest, Such groups, on average, produce more young than monogamous pairs, but on a per male basis (assuming that each male of a group has an equal chance to fertilize each young) polyandrous males produce fewer young per year than monogamous males. Territorial breeding birds show higher yearly survivorship (90%) than non-territorial, non-breeding birds (50% or less). All territorial birds seem to remain on their territories for life, and monogamous pairs actually constitute the remnants of polyandrous groups. Some potential factors producing such an unusual system are discussed. Limited breeding space and high mortality among non-territorial birds seem to work in favour of group breeding in this and other cooperative species. Polyandry may be favoured because of the reduced value of extra females in hawk breeding behaviour. Equal-status males may occur because of the lack of kinship among cooperating males and the high potential genetic cost of being a helper in a long-lived, low fecundity species. Other possible factors favouring group breeding are territory acquisition and the variable nature of the Galapagos climate.     

The destruction of source and sink habitats in the decline of the Mauritius Fody, Foudia rubra, an island-endemic bird

The population of the Mauritius Fody, Foudia rubra, a rare island-endemic bird, was structured as five subpopulations. The largest comprised small source areas contiguous with larger sink areas. The remainder were relicts, left by habitat destruction, from a time when the distribution was far more extensive. No evidence was found for a classical metapopulation structure. Destruction of source areas would have severe effects on population viability; their creation is the key to enhancing it. Following habitat destruction (1950–1975), fodies unexpectedly disappeared from habitat areas that were not destroyed; this probably occurred because the area destroyed contained source areas upon which adjacent, intact sink areas depended. The suggestion that introduced nest predators are likely only to affect native animal populations soon after their arrival is strongly rejected.     

Experimental evidence for innate predator recognition in the Seychelles warbler.

Nest predation is a major determinant of fitness in birds and costly nest defence behaviours have evolved in order to reduce nest predation. Some avian studies have suggested that predator recognition is innate whereas others have stressed the importance of learning. However, none of these studies controlled for the genetic origin of the populations investigated and the effect of unfamiliarity with the predator. Here we determined whether experience with a nest predator is a prerequisite for nest defence by comparing predator recognition responses between two isolated but genetically similar Seychelles warbler (Acrocephalus sechellensis) populations, only one of which had experience of the egg predating Seychelles fody (Foudia sechellarum). Individuals in the predator-free population significantly reduced nest guarding compared to individuals in the population with the predator, which indicates that this behaviour was adjusted to the presence of nest predators. However, recognition responses (measured as both alarm call and attack rates) towards a mounted model of the fody were equally strong in both populations and significantly higher than the responses towards either a mounted familiar non-predator and a mounted, novel, non-predator bird species. Responses did not differ with a warbler's age and experience with the egg predator, indicating that predator recognition is innate.     

Does competition for nests affect genetic monogamy in Cory's shearwater Calonectris diomedea?

Most bird species are socially monogamous. However, extra‐pair copulations (EPCs), resulting in extra‐pair paternity (EPP), commonly occur. EPCs should allow females to adjust social mate choice and allow males that fail to obtain a nest a chance to avoid missing a breeding season, especially when poor nest supply constrains social mate choice. Procellariiformes (albatrosses and petrels) are socially monogamous seabirds which seldom divorce, even when nest availability constrains social mate choice. In Cory's shearwater Calonectris diomedea, a burrow‐nesting petrel, two studies conducted in the Mediterranean, where competition for nests is weak, detected no EPP. EPP remains to be investigated at localities where competition for nests is much stronger, such as Vila islet, Azores archipelago, Atlantic Ocean. We conducted a genetic (microsatellites) study over two successive years on Vila, involving the breeding pairs of the same 65 nests each year and their single chick. EPPs occurred each year, the overall rate being 11.6%. Coupling genetic analyses to a 7‐year demographic survey provided additional data on pair bonds and competition for nests. Overall, cuckoldry was unrelated to divorce, nest density and inbreeding avoidance, but was more frequent when the social male was small. Nest changes were more costly for males than for females, and some apparently unpaired males attempted to dislodge social males during within‐pair copulations. These results are compatible with the existence of a link between poor nest availability and EPP and confirm that even species considered strongly monogamous can adopt flexible mating strategies.     

Genetic monogamy in single-male groups of acorn woodpeckers, Melanerpes formicivorus

Acorn woodpeckers have one of the most complex social systems of any bird species. Breeding units range in size from monogamous pairs to groups of 15 birds that include multiple breeding males and females as well as nonreproductive helpers-at-the-nest. Groups form when young remain at their natal nest to help their parents breed or when single-sex coalitions of siblings disperse to fill a reproductive vacancy on another territory. Plural breeding and helping behaviour are thought to be favoured through indirect fitness benefits for individuals that would otherwise be unable to breed due to a shortage of reproductive vacancies on territories with acorn stores. We report the results of multi-locus DNA fingerprinting of 51 offspring from 18 nests of 16 socially monogamous pairs of acorn woodpeckers. If socially monogamous females mate outside the pair-bond, indirect fitness benefits for cobreeders and helpers will be significantly reduced. Monogamous pairs accounted for all but one of the 51 offspring we tested; the single exception was apparently sired by the putative father, but the putative mother was excluded from maternity. Our results indicate that individuals remaining on their natal territories as helpers are generally the genetic offspring of the pair they help. They also suggest that single-sex coalitions offspring dispersing together from nests of socially monogamous pairs will be full-siblings.     

Parental care and social mating system in the Lesser Spotted Woodpecker Dendrocopos minor

The sexes’ share in parental care and the social mating system in a marked population of the single‐brooded Lesser Spotted Woodpecker Dendrocopos minor were studied in 17 woodpecker territories in southern Sweden during 10 years. The birds showed a very strong mate fidelity between years; the divorce rate was 3.4%. In monogamous pairs, the male provided more parental care than the female. The male did most of the nest building and all incubation and brooding at night. Daytime incubation and brooding were shared equally by the sexes, and biparental care at these early breeding stages is probably necessary for successful breeding. In 42% of the nests, however, though still alive the female deserted the brood the last week of the nestling period, whereas the male invariably fed until fledging and fully compensated for the absent female. Post‐fledging care could not be quantified, but was likely shared by both parents. Females who ceased feeding at the late nestling stage resumed care after fledging. We argue that the high premium on breeding with the same mate for consecutive years and the overall lower survival of females have shaped this male‐biased organisation of parental care. In the six years with best data, most social matings were monogamous, but 8.5% of the females (N=59) exhibited simultaneous multi‐nest (classical) polyandry and 2.9% of the males (N=68) exhibited multi‐nest polygyny. Polyandrous females raised 39% more young than monogamous pairs. These females invested equal amounts of parental care at all their nests, but their investment at each nest was lower than that of monogamous females. The polyandrously mated males fully compensated for this lower female investment. Polygynous males invested mainly in their primary nest and appeared to be less successful than polyandrous females. Polyandry and polygyny occurred only when the population sex ratio was biased, and due to strong intra‐sexual competition this is likely a prerequisite for polygamous mating in Lesser Spotted Woodpeckers.     

The social system of the Pale Chanting Goshawk Melierax canorus; monogamy v polyandry and delayed dispersal

The social organization and reproductive strategy of the Pale Chanting Goshawk Melierax canorus were investigated in four southern African study areas. Territories supporting adults additional to the breeding pair were observed in two study areas. Within one of these areas, these additional adults were either non-breeders staying in their natal territory but actively excluded from the nesting area during the breeding season or a male cobreeder participating fully in reproductive activities with the breeding pair. Polyandrous trios were, however, observed in only one vegetation type in this area, Broken Veld. The annual number of offspring fledged per group did not differ significantly between vegetation types nor between polyandrous trios and monogamous pairs within Broken Veld. Pale Chanting Goshawks lay predominantly two-egg clutches. In 2 out of 5 years, breeding groups succeeded in laying, hatching and even fledging a second brood of young after successfully fledging their first brood. Double brooding occurred more frequently in Broken Veld and most frequently in polyandrous trios in this vegetation type. To accommodate their relatively long breeding cycle (>115 days) in this temperate study area with its limiting summer breeding period, double-brooding Pale Chanting Goshawks laid the first clutch in midwinter and the second, on average, 24 days after the offspring from the first brood left the nest.     

Renesting and brooding in the Caribbean flamingo

Caribbean flamingos were observed during the 1981 breeding season at the Audubon Zoological Garden in New Orleans, Louisiana. Two floods occurred during the breeding season, causing the flock to nest three times. At each new nesting there was a significant decline in the number of birds laying eggs. One pair brooded a chick during the final nesting. Immediately after hatching, the female usually brooded while the male defended the nest area; however, over the three-day period that the chick remained on the nest, the male began to spend more time brooding and less time defending the nest area. Thus there appeared to be some division of labor in this flamingo pair.     

Red coloration of male northern cardinals correlates with mate quality and territory quality

I investigated how mate quality and territory quality influencean extravagant ornament in a socially monogamous species thatdefends multipurpose territories. Northern cardinals (Cardinaliscardinalis) are a highly dichromatic, socially monogamous species,and males are a brilliant red. I conducted a 3-year field studyof northern cardinals and found that redder males produced moreoffspring in a breeding season. Two selective factors mediatedthis fitness gain. Redder males were paired with earlier breedingfemales, an established measure of mate quality in birds. Second,redder males obtained territories of higher quality, as measuredby vegetation density. Interactions among these factors werealso important in explaining variance in male reproductive success.Multivariate analysis indicated that earlier breeding increasedreproductive success independent of territory quality. In turn,territory quality contributed to male reproductive success throughits effect on nest survival and possibly through its role in attractingan earlier breeding female.     

Extra-pair young despite strong pair bonds in the European Nuthatch (Sitta europaea)

We choose the European Nuthatch (Sitta europaea), an extremely socially monogamous passerine species, to investigate the breeding biology and frequency of extra-pair activities of females. Breeding individuals live in strong pair bonds for their total life and defend their territory all year round. As a consequence of these narrow social bonds, nuthatches have to date been considered extremely sexually monogamous. Our genetic study, however, reveals a minimum of 10% of extra-pair young in 188 chicks from 32 broods in populations of southwestern Germany. Independently of the habitat type (high via low quality), most of extra-pair sires are identified as neighbouring territory holders.     

Nesting success of the Mauritius Fody Foudia rubra in relation to its use of exotic trees as nest sites

Nest site choice and nesting success were studied in the Mauritius Fody Foudia rubra, a rare, island-endemic bird. Most pairs whose nests were found nested only in exotic plantation trees (Cryptomeria, Eucalyptus and Pinus) although native trees were available; around half of the total population nested in exotics. Most nesting failure resulted from nest predation, apparently by exotic Black Rats Rattus rattus and Crab-eating Macaques Macaca fascicularis. Nesting success was much higher in Cryptomeria (46%) than in other tree species (6%), and I conclude that this fact explains why fodies selected Cryptomeria for nesting. The same seems certain to be true for the Pink Pigeon Columba mayeri, which nested only in Cryptomeria. Larger samples of nests might reveal that Pinus and Eucalyptus support a nesting success intermediate between native trees and Cryptomeria, thereby explaining their use for nesting.     

Behavioural insensitivity to supplementary testosterone during the parental phase in the chestnut-collared longspur,Calcarius ornatus

In seasonally breeding male birds that show paternal care, plasma testosterone (T) peaks in the early spring coincident with territory establishment and pair bonding. Once nests are initiated, T declines precipitously and remains low as nestlings hatch and males become parental. A growing body of evidence suggests there is a trade-off between a male's level of T and his expression of paternal care: high T enhances sexual behaviour but reduces paternal care. Male chestnut-collared longspurs show high levels of paternal care. They feed and brood young, act as nest sentries and aggressively defend the nest against predators. We experimentally altered males' plasma levels of T such that the early spring T peak was extended through the parental phase. T enhanced song behaviour typical of the sexual phase and decreased nest sentry behaviour during incubation, but did not reduce brooding or feeding of nestlings. Thus, males responded behaviourally to T during incubation, but, unlike most other temperate-breeding birds studied, did not respond to T after eggs hatched. Based on these data and similar results in an Arctic passerine, we suggest that the pattern of males' reduced responsiveness to T during the nestling phase may reflect the relative importance of male care to nest success in this species, or a phylogenetic constraint common to the genusCalcarius . Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Experimental evidence that brighter males sire more extra‐pair young in tree swallows

Across taxa, extra‐pair mating is widespread among socially monogamous species, but few studies have identified male ornamental traits associated with extra‐pair mating success, and even fewer studies have experimentally manipulated male traits to determine whether they are related directly to paternity. As a consequence, there is little experimental evidence to support the widespread hypothesis that females choose more ornamented males as extra‐pair mates. Here, we conducted an experimental study of the relationship between male plumage colour and fertilization success in tree swallows (Tachycineta bicolor), which have one of the highest levels of extra‐pair mating in birds. In this study, we experimentally dulled the bright blue plumage on the back of males (with nontoxic ink markers) early in the breeding season prior to most mating. Compared with control males, dulled males sired fewer extra‐pair young, and, as a result, fewer young overall. Among untreated males, brighter blue males also sired more extra‐pair young, and in paired comparisons, extra‐pair sires had brighter blue plumage than the within‐pair male they cuckolded. These results, together with previous work on tree swallows, suggest that extra‐pair mating behaviour is driven by benefits to both males and females.     

Are Hazel Grouse Bonasa bonasia monogamous?

The apparently monogamous social organization of Hazel Grouse Bonasa bonasia previously had been inferred only from observations of unmarked birds. Using radio-marked Hazel Grouse, we confirmed that the social organization during the breeding season was indeed monogamous, the pair being the social unit. The pair bond, however, appeared relatively weak, as birds were together only 37% of the time during the prelaying period. We could not document mating behaviour, but observations suggested that most males mated monogamously and that at least 37% of the females had an opportunity to mate polyandrously because of (1) the seemingly weak pair bond, (2) attentive neighbouring males, (3) larger territory size of unpaired males, (4) extensive movements of some unpaired males, (5) sharing of a female by two males and (6) a potentially male-biased sex ratio.     

NOTICES

Steyn, P. 1975. Observations on the African Hawk-Eagle. Ostrich 46:87-105.

Observations extending over 12 years were made on two pairs of African Hawk-Eagles Hieraaetus spilogaster at Essexvale, Rhodesia. Details on various aspects of adult behaviour are given, particularly on hunting methods and calls. Nest repair usually took about 4–5 weeks. and limited observations indicated that the male does most of the work. Incubation is done mostly by the female, the male relieving her when he brings prey. The incubation period is 43 ± 1 day. Details are given of parental behaviour during the fedging period; time on the nest showed a progressive decline although both adults still perched in the. nest tree a great deal. The male provided most of the prey. The growth and behaviour of the eaglet Is described; usually the eaglet becomes a “brancher” before its first flight which, in four cases, occurred between 61–71 days. Post-of edping attachment to the nest lasted about three weeks in one case. Frief mention is made on the development of adult plumage. Birds made up 74%. mammals 25% and reptiles 1% of 104 prey items recorded at Essexvale. Gamebirds are preferred. The two nests had completely different breeding histories. One pair reared no young while the replacement rate of the other pair was 0,83 voung/pair/year. The combined replacement rate of the two pairs was 0,48 young/pair/year. There appear to be no records of two eaglets being reared together in southern Africa.     

Cooperative nest‐defence behaviour and territory quality in a resident and socially monogamous passerine

Nest defence is a fundamental aspect of parental care in secondary cavity‐nesting birds, and predation or competition for nesting sites can involve different defensive behaviours. Because habitat quality determines breeding success, we were interested in whether breeding pairs of the Eurasian nuthatch, Sitta europaea, established in more favourable environment also manifest higher probability of cooperative behaviour during their nest‐site defence. To explore this relationship, we quantified behavioural displays of both parents and analysed activity budget ethogram data from simulated territorial intrusions performed in the chick‐feeding phase with one conspecific and two different heterospecific stimuli (dummies of nuthatch, starling and woodpecker). We found that paired individuals shared their roles during nest‐site defence to a considerable extent. Males had a significantly higher number of attacks on intruders than females, and females performed more threat displays and controls of the brood than males. Multinomial analysis of the cooperative behaviour suggested that pairs in a high‐quality territory had higher probability of reciprocal substitution of different roles towards a balance between attacks, threat displays and nest controls. Contrary to this, pairs in a low‐quality territory had less likely pairwise combinations of simultaneous behavioural states that are associated with effective nest‐site defence. The difference in response probability according to territory quality was, however, highly variable in view of the stimulus that was used in simulated territorial intrusion. Because individual roles and the complex behavioural repertoire of pairs altered in response to territory quality and potential nest‐site competitor or brood predator, our results suggest that the cooperative nest‐defence behaviour could be linked to the breeding success of this year‐round territorial species living in a heterogeneous forest habitat.     

A FIELD STUDY OF THE BEARDED BELLBIRD IN TRINIDAD

The Bearded Bellbird Procnias averano, a medium-sized sexually dimorphic cotingid, was studied for three years in the Northern Range of Trinidad. Its preferred habitat is primary forest at altitudes of 500–1,000 feet and with a rainfall near 100 inches. It is entirely frugivorous, taking mostly drupes. The seeds of the fruits eaten are regurgitated and nearly 2,000 were collected from below the male's calling perch and below nests. Most were from the families Lauraceae and Burseraceae, whose fruits have particularly nutritious pericarps. Adult males own a calling territory from which they call throughout most of the day, and throughout the year except for the period of moult. In each territory there are special saplings where display and mating take place. Only males call; the females are voiceless. The call is loud and far-reaching. In Trinidad P. averano has only two calls, the Venezuelan birds have a third more musical call which appears to have been lost by the Trinidad bellbird during the past 60 years. Both males and females visit the adult male in his calling territory. Here he performs a ritualized display to the visitor, which shows off his black and white plumage, the beard of wattles, and also a bare patch on the thigh. The visit of the female may culminate in mating. All aggressive behaviour observed was between males disputing over calling territories. The female builds the nest, incubates, and rears the chick on her own. The very inconspicious nest is built of twigs that readily interlock. Nearly all the twigs are from two species of tree, and it is suggested that the specialized nest-material may be essential, as the female bellbird builds only with the breast and feet. The clutch consists of a single egg. The incubation and fledging periods are both long, 23 and 33 days respectively. The female's visits to the chick are infrequent, brief, silent and inconspicuous. Many details of breeding behaviour indicate that the inconspicuousness of the nest is of paramount importance. The nestling is fed on fruit which the female regurgitates. The main breeding season is from April to July with a minor one in October and November. It takes two and a half years for the male to attain fully adult plumage, and at least two years to achieve a completely adult call. The relationship between type of nest, clutch-size, feeding habits and sexual bonds in tropical forest birds is discussed. The bellbird is an extreme example of a species in which the need for a very inconspicuous nest and a diet of fruit have combined to promote polygamy, with the emancipation of the male from the nest, and to reduce clutch-size to a minimum. The bellbird's structural adaptations to its method of feeding in flight are discussed and a comparison is made with the birds of paradise. The male's adaptations for its primary function of self-advertising are compared with the parallel adaptations evolved in the related Pipridae.     

Social aspects of the termination of incubation behaviour in the ring dove (Streptopelia risoria)

The role of male and female ring doves (Streptopelia risoria) in the termination of incubation behaviour was studied first by observing heterosexual pairs (male and female) and homosexual pairs (female and female) (experiment 1). Male/female pairs incubate for 22 days whether squab or unhatched eggs are in the nest; female/female pairs incubate for 25 days or more. Males take the lead in terminating incubation. Another group of doves, separated from their (heterosexual) partners late in incubation, were exposed to one of four stimulus conditions: (a) an incubating dove; (b) a reproductively-inactive dove; (c) a reproductively-active dove; (d) visual isolation. Females extended the duration of their incubation when exposed to the sight of another dove, except when the stimulus dove was reproductively active. Males did not extend their incubation in response to these social cues. These social stimuli terminating incubation behaviour coordinate the withdrawal from the nest of male and female in preparation for the next breeding episode in this monogamous species.