A 13-YEAR POPULATION STUDY OF THE BLACK EAGLES IN THEMATOPOS,RHODESIA, 1964–1976

Gargett, V. 1977. A 13-year population study of the Black Eagles in the Matopos, Rhodesia, 1964–1976. Ostrich 48:17-27.

The resident black Eagle Aquila verreauxi population in approximately 620 km² of the Matopos, Rhodesia, underwent changes from 1971 and appeared less stable than in the first five years. Six new territories were established in the National Park; two territories in Tribal Trust Land were abandoned; one territory in the National Park vacant for five years and one in Tribal Land vacant for at least 11 years were reoccupied. breeding data covering 13 years confirm the five-year findings. In 652 pair-years 442 breeding attempts were made with 339 young eagles f edging: a reproductive success rate of 0,52 young per pair per year. On average 68 % of the population bred every year, each pair attempted breeding in two years out of three, and one attempt in four was unsuccessful. Annual and individual variations in breeding performance were considerable, from 46% to 89% of the population breeding, and from two successes in six attempts for one pair to 12 successes in 12 attempts for two pairs. Over 13 years the percentage of the population breeding annually followed the form of a sine curve with a ten year period.

Fourteen factors that might affect annual and/or individual performance are considered. Below average rainfall years were followed by above average breeding; and generally fewer clutches were laid early after heavy rainfall in the three months preceding laying. Clutches laid late were less successful than those laid early. Breeding was affected by the proximity and intervisibility of nests, the previous year's performance and intraspecific disturbance. Appropriation of nests by other species prevented breeding and no new pair bred while establishing or re-establishing its territory. Building a new nest was followed by laying in the same season only if the nest was completed by mid-May, the peak laying period, building or partly building two nests in one season did not prevent breeding in the following year. At least 76% of clutches were c/2. The causes of two eaglets' deaths were ascertained and the remains of two adults were found. Pairs with territories in Tribal Trust Land had a significantly lower breeding performance than pairs in the protected National Park. Only traces of pesticide residues were found in four eggs. Observers' visits did not affect reproductive success.     

Reproduction and survival of suricates (Suricata suricatta) in the southern Kalahari

In most respects, the demography of Kalahari suricates (Suricata suricatta) resembles that of other social mongooses. Average group size varies from four to nine, and groups typically include several mature females, of which one is responsible for the majority of breeding attempts. Breeding females show a postpartum oestrus; gestation is around 60 days; litter size is three to five pups at emergence and females rarely breed before the age of 24 months. In contrast, annual survival rates (0.20 for pups and 0.43 for animals over one year old) are lower than those recorded in other species. Breeding frequency is related to rainfall and breeding can cease altogether when rainfall is unusually low. In a year when this occurred, group size eroded rapidly and over 60% of groups became extinct. Total numbers were slow to recover during the following year because emigration by females was infrequent and new groups did not form in vacant ranges created by the extinction of groups. High rates of group extinction have been found in other cooperative breeders and may occur because breeding success and survival show inverse density dependence.     

Determinants of quality in a long-lived colonial species

1. In many animal populations a small proportion of individuals produce the majority of surviving offspring, but the underlying mechanisms are unclear. Behaviour may be an important determinant of variation in fitness: 'high-quality' individuals may have enhanced abilities in foraging or predator and parasite avoidance. 2. The role of behaviour in determining variation in quality was examined using the common guillemot Uria aalge, a monogamous seabird with biparental care. Using a novel mixed model approach, we analysed binary data on breeding success of each pair attempting to breed in each year with variables critical to breeding success (timing of breeding; inferred age; breeding experience and success; number of nest sites and partners) as fixed effects. Random effects for year, male, female and each distinct pairing of a male and a female were included in the model, allowing a quality estimate to be derived for each individual and pair. A range of behaviours associated with breeding were examined in relation to these quality estimates. 3. Breeding success declined with timing of breeding, and increased initially with age before declining in old age. It increased with previous successful experience, not breeding experience per se, until senescence effects became apparent. For males, breeding success declined with increasing numbers of mates. 4. The most important behavioural determinants of quality operated at the level of the pair, with the time mates spent together at the site and chick feeding rates both positively related to quality. At the individual level, trip durations and feeding rates were associated with female but not male quality, suggesting that pair quality was operating principally through the female. However, removal of laying date, the most important component in the binomial model, confirmed that the pair effect was much larger than the female effect. 5. This study demonstrates the potential of mixed modelling to determine quality estimates based on long-term breeding histories. The probability of a successful reproductive attempt was explained by the timing of breeding, age, successful breeding experience and number of mates. Behaviour was an important proximate mechanism underlying quality, in particular the foraging abilities of the pair, and the female's contribution to offspring provisioning. In species with biparental care, behavioural correlates of quality operate most strongly at the scale of the breeding pair, because contributions from both individuals are required for a successful outcome.     

Acquisition of Breeding Space by Nonbreeders in the Anemonefish Amphiprion clarkii in Temperate Waters of Southern Japan

Behavior of Amphiprion clarkii, especially of nonbreeders, was investigated at the shore of boulders and rocks in Uwa Sea, southern Japan. All individuals except small ones under one year were tagged. Movements of A. clarkii between host sea anemones were usual in this study area where host anemones were abundant, unlike in the general habitat (coral reefs) of Amphiprion, where movements between hosts are restricted. Monogamous pairs established almost contiguous territories containing all hosts except small ones. Nonbreeders had home ranges on the fringes of the pairs' territories and sheltered in relatively small hosts. Breeding spaces were saturated with breeders and were available for nonbreeders only after disappearance of one or both members of an established breeding pair. Home ranges of nonbreeders of similar body size were spaced out, due perhaps to competition for breeding spaces. It is suggested that large nonbreeders refrained from becoming females to keep their gonads ambosexual, so that they could replace either sex in a territory as breeding space became available, or, in pairing with other nonbreeders, the larger fish of the pair could take the female role.     

Negative population trend for Chapada Flycatchers (Suiriri islerorum) despite high apparent annual survival

ABSTRACT Population size and trends are demographic parameters that can be used to help determine the threat of extirpation or extinction of bird populations and in determining management strategies. Chapada Flycatchers (Suiriri islerorum) are endemic to the Cerrado region of Brazil, dependent on open cerrado habitat, defend large territories, and their populations seem to be declining. From 2003 to 2007, we analyzed demographic parameters of a declining population of Chapada Flycatchers, using the rate at which territories became vacant and the size of the breeding population to ascertain the status of the population, and evaluated the relative contributions of apparent annual survival and recruitment rates to these trends. Territories became vacant at a mean rate of 13% per year, and 32% of all territories were vacated during our study. The current breeding population (20 pairs) was at least seven times smaller than the estimated carrying capacity of the reserve (141 territorial pairs). Estimated apparent annual survival probabilities (0.77 for breeders; 0.67 for nonbreeders) based on model averaging were comparable to those reported for other Neotropical passerines. Survival rates did not differ between the sexes and the estimated recruitment rate was 0.21. In many species, adult survival is the factor that most strongly influences population growth rates. However, the population of Chapada Flycatchers we studied is declining despite high annual survival rates, with low and variable breeding success probably causing the decline. Our results improve our understanding of the possible role of adult survival and breeding success in the decline of populations of small passerines in isolated reserves in the tropics.     

Habitat variation and population regulation in Sparrowhawks

In a study area in south Scotland, Sparrowhawks did not occupy the available nesting places at random, but more often used those places where breeding success was highest (here called high-grade places). Most birds stayed on particular nesting places for only one year, but others stayed up to 8 years. Some birds moved from low- to high-grade places as they aged. Continued occupancy of certain places was thus produced by many different individuals occupying such places in rapid succession, but most staying for only one breeding season.
On the most used (high-grade) nesting places pairs produced more than enough young per breeding attempt to offset the average annual mortality, but on the less used (low-grade) places they produced too few. Low-grade nesting places therefore acted as a sink, whose occupancy could be maintained only by continual immigration. Over the study area as a whole, the population was in balance, with reproduction matching mortality.
Habitat changed over periods of 15–30 years, as woodland matured. Nesting places in young woods, with small densely-growing trees, showed the highest occupancy and nest success. Both aspects of performance declined as the woodland aged, and trees became larger and more widely spaced. Long-term stability in nest numbers and success in the study area as a whole was associated with a system of rotational forest management, which ensured a continuing availability of young woods.
It is proposed that spatial variation in habitat quality is involved in the regulation of breeding numbers. Removal experiments confirmed the presence of non-breeders, which could attempt to breed when high-grade nesting habitat was made available to them, but otherwise remained as non-breeders despite the presence of vacant low-grade habitat. This situation, involving an interaction between habitat quality and bird quality, probably occurs in some other raptors too.     

Home-ranges and patterns of spatial use in territorial Bonelli's Eagles Aquila fasciata

Bonelli's Eagle Aquila fasciata is one of the rarest birds of prey in Europe, where it has suffered a significant decline in recent decades. We present information on the home-ranges and spatial parameters of 18 Bonelli's Eagles radiotracked in 2002–2006 in Catalonia (northeast Spain) and describe the home-range probability kernel, distances moved, breeding area eccentricity, territorial overlap, nearest neighbour distance and breeding site fidelity, and assess the influence of sex, breeding status, season and geographical area on these parameters. Median home-range according to the minimum convex polygon (MCP) and 95% kernel were 50.3 and 36.1 km², respectively. The median breeding area eccentricity was 1477 m. There was considerable overlap in the home-range of both sexes within pairs (MCP: 71.4% and 95% kernel: 98.5%), indicating close pair bonding and similar foraging patterns. Overlap in home-ranges of up to 15% between neighbouring individuals also occurred and was positively related to breeding pair density. There was no difference in spatial parameters between sexes or with breeding status, but during the non-breeding season Eagles had larger home-ranges and stayed further from nests. The high consistency across birds suggests a pattern of spatial use that is characteristic of this species. The high level of use of breeding areas and their surroundings (50% kernel) throughout the year makes it important that these areas be protected from human disturbance. Additionally, it is necessary that heavily used areas away from nesting sites, which are used for foraging and roosting, are identified, protected and managed in a sustainable fashion.     

Patterns of territory settlement and consequences for breeding success in the Northern Wheatear Oenanthe oenanthe

We examined the pattern of territory settlement and its consequences for breeding success in the Northern Wheatear Oenanthe oenanthe on Bardsey Island, Wales, during the breeding seasons of 1991-93. Males returned earlier than females, and older males returned earlier than first-year breeders. Although their boundaries shifted between years, the general location of territories was consistent during the three-year study. There was a high degree of fidelity to area and territory between years for both sexes. The order of territory settlement, from which a territory rank was calculated, was highly consistent for males between years irrespective of individual settlement patterns and territory fidelity. Patterns of territory settlement were less predictable for females, although there was a significant correlation between the mean territory ranks of paired males and females. There was a male-biased sex ratio in each year, and between 5% and 26% of males remained unpaired throughout the breeding season. Male mating status and breeding success were dependent on arrival date, territory rank and breeding density. Early-arriving, usually older, males were able to settle on territories first and were more likely to pair, while later-arriving individuals were more likely to remain unmated. These effects were consistent between years, and consequently territories could be classified as either preferred (accounting for proportionately more breeding attempts) or non-preferred. Territory quality as opposed to individual quality appeared to explain much of the variation in breeding success, and both sexes benefited by breeding on preferred territories through enhanced breeding success and an increased probability that their offspring would be recruited to the population.     

Movements and home range of ferrets (Mustela furo) at Pukepuke Lagoon,New Zealand

Abstract

Ferrets at Pukepuke Lagoon were live-trapped during the periods November 1970 to August 1973 and January 1976 to July 1977. Although the sex ratio of the 75 trapped ferrets was equal, there was a strong bias towards male captures in the earlier period (58.4%) and towards female captures in the later period (68.7%). Habitat modification and changes in the trapping programme for the later period probably resulted in the increased abundance and capture rate of females. Between consecutive captures 58.2% of male movements exceeded 250 m, as against on1y 39.7% of female movements; the mean distance between consecutive captures was 435 m for males and 285 m for females. Mean monthly movements varied from 700 m in January to 315 m in June for males, and from 360 m in March to 150 m in September for females. Juveniles of both sexes moved similar, intermediate distances. Dispersing juveniles were trapped from January until April; males tended to appear in traps earlier in the year than females. Only 4 of 14 juvenile males setNed as residents, hut 15 of 28 juvenile females did so. Male and female home ranges overlapped extensively, but within each sex individual ranges were usually separate. Resident males maintained a well defined spacing pattern, adjusting their boundaries if a juvenile settled or a neighbouring range became vacant. In 1976 six females had overlapping ranges in an area of albundant food. Female ranges (12.4 ha) were on average smaller than male ranges (31.3 ha); home ranges of both sexes were smaller during the breeding season (August-February) than at other times.     

Better off alone! Reproductive competition and ecological constraints determine sociality in the African striped mouse (Rhabdomys pumilio)

1.?While the reasons for group-living have been studied for decades, little is known about why individuals become solitary. 2.?Several previous experimental studies could demonstrate that group-living can arises as a consequence of ecological constraints. 3.?It has been argued that reproductive competition between group members leads to significant costs of group-living, being a main reason of solitary-living. However, so far, no studies tested experimentally whether reproductive competition can explain solitary-living. 4.?Using a socially flexible species, the African striped mouse (Rhabdomys pumilio), we tested experimentally in the field whether dispersal and solitary-living are more likely to occur when reproductive competition is present. 5.?We investigated ecological constraints, here expressed as a function of population density, by removing groups of striped mice and creating vacant territories. To control for the effect of reproductive competition, which occurs only during the breeding season, we performed experiments during both the breeding and the non-breeding season. This is the first removal experiment performed in a species with communal breeding during the non-breeding season. 6.?During the breeding season, when population density was low, more striped mice from experimental groups moved into the vacant territories and became solitary than striped mice from control groups. This is in support of the ecological constraints hypothesis. 7.?During the non-breeding season, striped mice remained group-living despite the availability of free territories. Significantly, more striped mice became solitary-living during the breeding than during the non-breeding season. This is the first experimental support for the reproductive competition hypothesis explaining solitary-living. 8.?Analysis of the sexual maturity of males showed that males which became solitary had a higher reproductive potential than males that remained group-living. Analysis of the body mass data of females showed that more solitary females reproduced than group-living females. These results indicate that by becoming solitary individuals of both sexes avoided costs of reproductive competition within groups. 9.?Our study provides experimental evidence that reproductive competition within groups can lead to dispersal and solitary-living.     

Sex-biased dispersal: a result of a sex difference in breeding site availability

Sex-biased dispersal is often explained by assuming that the resource-defending sex pays greater costs of moving from a familiar area. We hypothesize that sex-biased dispersal may also be caused by a sex bias in breeding site availability. In avian resource-defense mating systems, site availability is often more constrained for females: males can choose from all vacant sites, whereas females are restricted to sites defended by males. Using data on breeding dispersal of a migratory passerine, we show that average number of available breeding options and availability of the previous year's territory was greater for males than females. The female bias in site unavailability may explain the female bias in probability of breeding dispersal because there was no sex bias in dispersal among birds with their previous year's territory available. We suggest that sex biases in the availability of breeding options may be an important factor contributing to observed variation in sex-biased dispersal patterns.     

Winter male plumage coloration correlates with breeding status in a cooperative breeding species

The function of colored ornaments is usually related to thesignaling of individual quality in intra- and intersexual interactions.In cooperative breeding species, where only a fraction of themale population access the breeding status and the other fractionhas the option to help breeding pairs, colored traits mightprovide the females with a reliable information on the qualityof potential mate. Males of the cooperative breeding azure-wingedmagpies (Cyanopica cyanus) display conspicuous blue plumagecoloration. Here we explored the role played by structural bluecoloration of males and the probability of becoming a breederor a helper. Birds were trapped during 4 consecutive years,and feather coloration was measured with a spectrometer. Malesthat became breeders had a more brilliant and saturated bluecoloration and showed a more violet hue in the nonbreeding periodcompared with birds that became helpers. Breeding males alsoshowed a seasonal decline in blueness, whereas the color propertiesof helpers were constant throughout the year. Blueness of individualstrapped in the nonbreeding period was positively correlatedwith body size and condition. These findings are consistentwith a scenario in which nonbreeding blue plumage colorationmay function as a signal of individual quality in the azure-wingedmagpie at the pair formation time and add to growing evidencesuggesting that the nonbreeding season appears particularlyimportant in impacting breeding roles in cooperative breedingbirds.     

Is the Sacred ibis a real threat to biodiversity? Long-term study of its diet in non-native areas compared to native areas

This paper presents the results of a 14-year study about the diet of the Sacred ibis in its main introduction area in France and its impact on native bird species, and compares the data to literature from its native area. During an initial period (1993–2004), the diet was essentially composed of invertebrates such as common aquatic insects (correlated with flooding) or Eristalis larvae picked from the mud (a vacant food niche in France), while scraps of meat taken from rubbish dumps were minor. These traditional preys taken from the same ecosystems as in its native area did not result in an exponential increase of the number of breeding Sacred ibises. Invasive Red swamp crayfish recently replaced other foods in its diet with a resulting sharp increase in breeding pair numbers (R² = 0.48). As in other parts of the world, vertebrates constituted very accidental preys, and no bird species were really threatened by such predation. Conversely, the Sacred ibis can have a positive effect as a predator of invasive crayfish. Adding the species to the DAISIE list of the 100 most invasive alien species in Europe therefore appears debatable.     

Effects of pair migratory behavior on breeding phenology and success in a partially migratory shorebird population

In migratory systems, variation in individual phenology can arise through differences in individual migratory behaviors, and this may be particularly apparent in partial migrant systems, where migrant and resident individuals are present within the same population. Links between breeding phenology and migratory behavior or success are generally investigated at the individual level. However, for breeding phenology in particular, the migratory behaviors of each member of the pair may need to be considered simultaneously, as breeding phenology will likely be constrained by timing of the pair member that arrives last, and carryover effects on breeding success may vary depending on whether pair members share the same migratory behavior or not. We used tracking of marked individuals and monitoring of breeding success from a partially migrant population of Eurasian oystercatchers (Haematopus ostralegus) breeding in Iceland to test whether (a) breeding phenology varied with pair migratory behavior; (b) within‐pair consistency in timing of laying differed among pair migratory behaviors; and (c) reproductive performance varied with pair migratory behavior, timing of laying, and year. We found that annual variation in timing of laying differed among pair migratory behaviors, with resident pairs being more consistent than migrant and mixed pairs, and migrant/mixed pairs breeding earlier than residents in most years but later in one (unusually cold) year. Pairs that laid early were more likely to replace their clutch after nest loss, had higher productivity and higher fledging success, independent of pair migratory behavior. Our study suggests that the links between individual migratory behavior and reproductive success can vary over time and, to a much lesser extent, with mate migratory behavior and can be mediated by differences in laying dates. Understanding these cascading effects of pair phenology on breeding success is likely to be key to predicting the impact of changing environmental conditions on migratory species.     

A Polygamous Social System of the Fan-tailed Warbler Cisticola juncidis

The social system of an individually-marked population of the fan-tailed warbler Cisticola juncidis was studied in Japan, over six breeding seasons from 1978 to 1983. More than 127 males established territories, some 50–70% were polygynists each year. Territorial males were replaced frequently within seasons. Females were less faithful than males to their first breeding sites. Perennial or seasonal pair bonds were rare, maintained over two successive breeding attempts, by only 13.6% of females. Half the females left the area after one breeding attempt. Frequent divorce, rapid and multiple remating of females, multiple breedings, and female movement over a wide area all combine to skew breeding sex ratio from unity and favor polygyny.     

Pair bond characteristics and maintenance in free‐flying jackdaws Corvus monedula: effects of social context and season

Most birds rely on cooperation between pair partners for breeding. In long‐term monogamous species, pair bonds are considered the basic units of social organization, albeit these birds often form foraging, roosting or breeding groups in which they repeatedly interact with numerous conspecifics. Focusing on jackdaws Corvus monedula, we here investigated 1) the interplay between pair bond and group dynamics in several social contexts and 2) how pair partners differ in individual effort of pair bond maintenance. Based on long‐term data on free‐flying birds, we quantified social interactions between group members within three positive contexts (spatial proximity, feeding and sociopositive interactions) for different periods of the year (non‐breeding, pre‐breeding, parental care). On the group level, we found that the number of interaction partners was highest in the spatial proximity context while in the feeding and sociopositive contexts the number of interaction partners was low and moderately low, respectively. Interactions were reciprocated within almost all contexts and periods. Investigating subgrouping within the flock, results showed that interactions were preferentially directed towards the respective pair partner compared to unmated adults. When determining pair partner effort, both sexes similarly invested most into mutual proximity during late winter, thereby refreshing their bond before the onset of breeding. Paired males fed their mates over the entire year at similar rates while paired females hardly fed their mates at all but engaged in sociopositive behaviors instead. We conclude that jackdaws actively seek out positive social ties to flock members (close proximity, sociopositive behavior), at certain times of the year. Thus, the group functions as a dynamic social unit, nested within are highly cooperative pair bonds. Both sexes invested into the bond with different social behaviors and different levels of effort, yet these are likely male and female proximate mechanisms aimed at maintaining and perpetuating the pair bond.     

Prospecting in a solitary breeder: chick production elicits territorial intrusions in common loons

In many species, young animals learn about various breedingpatches in one year and use what they have learned to settlein a promising patch the next. Common loons (Gavia immer) seemgood candidates for such prospecting as prebreeders and displacedbreeders intrude frequently into breeding territories defendedby monogamous pairs yet engage in no extrapair copulations.We tested 3 hypotheses for prospecting in loons. The permanentattributes hypothesis gained little support as we found no consistentdifferences in quality between territories and no physical orbiotic trait that predicted reproductive success in a territory.We found some support for the conspecific attraction hypothesisas intruders were attracted to conspecifics in a lake in theshort term; however, intrusions were not more frequent in territoriesthat had experienced regular use by a pair the previous yearthan in territories that had previously been vacant. Instead,the increase in intrusion rate after a year of chick productionsupported the habitat-copying hypothesis, which states thatfloaters use the presence of chicks as a cue to target territoriesfor future attempts at territorial takeover. Despite this systemof prospecting, founding of new territories was common. Onestriking finding was the tendency of territorial breeders toconceal chicks from flying intruders, perhaps to avoid futureterritorial takeover.     

Age-assortative pairing in the Greater Flamingo Phoenicopterus ruber roseus

Among long-lived bird species, the partners of breeding pairs are often of similar age. This pattern is largely influenced by little variation in the age at first breeding, linked with high survival rate and prolonged pair bonds. Contrary to other long-lived colonial species, Greater Flamingos Phoenicopterus ruber roseus do not show mate fidelity over consecutive breeding seasons. We studied pairing patterns of Greater Flamingos breeding in the Camargue, southern France, between December 1989 and March 1992. In each year, significant correlations were observed between the ages of the male and the female in a pair. The pattern of age-assortative mating was confirmed independently in each year by comparing the frequency distribution of age differences within pairs with the theoretical distribution derived from the age distribution of paired birds of known age in the population, assuming random pairing with respect to age. There was no evidence of a differential time of return each year to the colony with age. Analysis of display behaviour suggested that age-as-sortative mating in the Greater Flamingo results from a directional pairing preference for older and more experienced individuals. The present study provides direct evidence that age-assortative mating can occur independently of mate fidelity.     

The annual cycle and breeding behaviour of the Mauritius Fody Foudia rubra

Safford, R.J. 1997. The annual cycle and breeding behaviour of the Mauritius Fody Foudia rubra. Ostrich 68 (24): 58–67.

The Mauritius Fody Foudia rubra, a highly endangered species of weaver (Ploceidae) endemic to Mauritius, was studied from 1989–1993. The plumage, various display postures (typical of the family), and seven adult and two juvenile vocalisations are described. The diet consisted of insects, nectar and fruit. Males were in breeding plumage, and breeding took place, between late August and early April, although severe weather in February 1992 terminated breeding activity early. The species appeared to be monogamous and was suspected to maintain a long-term pair bond. Pairs occupied exclusive territories of not less than 0.9 ha. Both sexes built the nest from the outset, but only the female lined it. Between breeding attempts, some pairs habitually started but then abandoned one or more nests. Clutch sizes of two to four were recorded, three being the norm. Incubation and brooding were carried out by the female; the male joined in feeding the young after daytime brooding ceased. Juvenile dependency appeared to last around two weeks after which the young were ousted from the territory. The potential productivity of up to three broods per pair per year was not achieved by any pair studied because of poor nesting success. A complete moult followed breeding. Territorial defence continued throughout the year, and no evidence for seasonal movements was seen. Two behavioural features seem unexpected: 1) male nest invitation and nest advertisement behaviour appeared to be absent; 2) females participated from the outset of nest-building (including prospecting). These could be explained by the existence of a long-term pair bond, which needs to be confirmed but would not be surprising in a species that remains on territory all year. Hypotheses that could be tested to find a mechanism responsible for the unusual features of the fody are suggested. In comparison with other fodies studied, the breeding behaviour most resembled that of the Seychelles Fody F. sechellarum (also a monogamous, non-graminivorous omnivore that breeds in solitary pairs in evergreen forest). The annual cycle was similar to that of other native passerines and most other fody taxa.     

Evidence that helping at the nest does not result in territory inheritance in the Seychelles warbler

In an environment that has a shortage of territories, helping to rear younger siblings ('alloparenting') is proposed to facilitate territory acquisition in two ways: (i) through group augmentation that leads to an increase of the territory with subsequent partial inheritance (budding); and (ii) through site dominance that leads to greater success when competing for the natal or a nearby territory after the death of the territory owner (complete territory inheritance). Most young Seychelles warbler (Acrocephalus sechellensis) males either show alloparenting or budding behaviour. Future budders had significantly more aggressive interactions with neighbours and assisted their parents more with territory defence than similarly aged future alloparents or non-helpers. This led to an increase of the natal territory of future budders before actual budding took place, whereas the natal territories of future alloparents remained constant in size. Alloparents never became budders and vice versa, refuting partial inheritance as an advantage of alloparenting. Natural male breeding vacancies were never inherited by alloparents born on vacant or other territories, but were inherited by budders born on the vacant territory or, if these were absent, predominantly by budders from neighbouring territories. We offer explicit experimental evidence against the 'helping at the nest to inherit' hypothesis. Experimentally created male breeding vacancies, with both a male alloparent and a similarly aged sibling budder present simultaneously in the vacant territory, were filled by budders only. Site dominance over territory inheritance is linked to budding and not to alloparenting.