NOTE ON THE NIDIFICATION OF

Palearctic migrant birds are declining, including the Northern Wheatear, and some of the causes of these declines are likely to be operating on their wintering grounds in Africa. We examined seasonal and spatial variation in wintering densities of Northern Wheatears in northern Nigeria, and explored the species’ habitat associations on the wintering grounds to assess the likely effects of habitat change in the Sahel on this species. Densities of Northern Wheatears across northern Nigeria were calculated from point count data gathered during two winters (2000 and 2001) using Distance software, and the relationships between Wheatear presence and habitat variables collected from the same points were explored using general linear models. During mid-winter and early spring, densities of Northern Wheatears peaked, with significantly more birds present in western than eastern study sites. The probability of wheatear occurrence was correlated with Balanites and Salvadora tree density and mean tree height. The Northern Wheatear may benefit from the conversion of woodland habitats in the Sahel to more open savanna. However, sites with very low tree densities showed low probabilities of Northern Wheatears being present, suggesting excessive tree clearance may have a negative effect upon the species.     

Genetic structure among remnant populations of a migratory passerine,the Northern Wheatear Oenanthe oenanthe

Continuous animal populations often become fragmented due to anthropogenic habitat alterations. These small, fragmented populations are fragile due to demographic and genetic factors, whereas immigration can enhance their long‐term viability. Previously, we showed that high philopatry affected the local dynamics of three small and remnant subpopulations of Northern Wheatears in The Netherlands. Here, we show that these three populations together with an additional larger population in the European lowlands are highly genetically differentiated based on 22 microsatellite markers. In contrast, we found no evidence for differentiation using two mitochondrial DNA markers. An IMa2 analysis indicates that gene flow has occurred regularly among our sampled populations. As immigration of colour‐ringed birds among our sampled populations is rare at best, our results suggest that the populations have recently become isolated from one another. Low dispersal rates in highly mobile birds may occur when suitable habitat becomes highly fragmented, and will accentuate stochastic demographic processes and inbreeding, both reducing population viability. As dispersal rates are low among populations of Northern Wheatears in The Netherlands, there is only a small probability of recolonization of habitat patches where populations have become locally extinct.     

Morphometric diagnosability of Cyprus Wheatears Oenanthe cypriaca and an unexpected occurrence on Helgoland Island

Capsule We found closely related Cyprus Wheatears Oenanthe cypriaca and Pied Wheatears Oenanthe pleschanka to differ significantly from each other in 14 external morphometric characters, supporting the independent taxonomic status of both forms. An additionally measured old specimen from Helgoland unexpectedly turned out to be a Cyprus Wheatear, the first record for Germany.     

Winter territoriality and its implications for the breeding ecology of White-throated Dippers Cinclus cinclus

Capsule: Pairs of White-throated Dippers Cinclus cinclus which defended winter territories bred earlier than non-territorial individuals, but there was no difference in reproductive success.

Aims: The effect of winter territoriality on breeding ecology has rarely been studied in resident birds. We carried out a preliminary investigation of whether winter territorial behaviour and territory size affect the timing of reproduction, breeding territory size and reproductive success in a riverine bird, the White-throated Dipper.

Methods: We monitored an individually marked population of White-throated Dippers in the UK. Wintering individuals were classified as either territorial or ‘floaters’ according to their patterns of occurrence and behaviour, and their nesting attempts were closely monitored in the subsequent months. Winter and breeding territory sizes were measured by gently ‘pushing’ birds along the river and recording the point at which they turned back.

Results: All birds defending winter territories did so in pairs, but some individuals changed partners before breeding. Territorial pairs that were together throughout the study laid eggs significantly earlier than pairs containing floaters and those comprising territorial birds that changed partners. However, there were no significant differences in clutch size, nestling mass or the number of chicks fledged. There was no relationship between winter territory length and lay date or any measure of reproductive success, although sample sizes were small. Winter territories were found to be significantly shorter than breeding territories.

Conclusion: Winter territoriality may be advantageous because breeding earlier increases the likelihood that pairs will raise a second brood, but further study is needed. Territories are shorter in winter as altitudinal migrants from upland streams increase population density on rivers, but this may also reflect seasonal changes in nutritional and energetic demands.     

Resident female Northern Lapwings Vanellus vanellus fight to exclude settlement by secondary females

In systems with bi‐parental care, sexual conflict theory states that a transition from monogamy to polygyny should increase fitness prospects for males and reduce fitness prospects of resident females. Behavioural observations of Northern Lapwings Vanellus vanellus suggested that resident females try to monopolize their breeding resources by attacking females prospecting for secondary status, and males commonly respond by intervening on behalf of the prospecting females. In four territories the resident females successfully defended their monogamous status, in nine territories the resident females made at least one successful eviction before being forced to accept polygyny and in nine territories observed eviction attempts were unsuccessful. These observations indicate that mating status in Northern Lapwings is partly determined by the competitive ability of resident females.     

The importance of alder to hazel grouse in Fennoscandian boreal forest: evidence from four levels of scale

Buds and staminate catkins of alder (Alnus spp) form an important winter food for hazel grouse Bonasa bonasia in the Fennoscandian boreal forest Alder was found to be highly preferred over other deciduous trees, particularly alders ≥ 10 m tall and ≤15 m from spruce forest Winter territories were probably feeding territories, as size was correlated negatively with alder density and almost significantly correlated negatively with competitor density All winter territories were found to contain ample winter food resources for hazel grouse However, the distribution of territories was associated significantly with the distribution of alders at two levels of scale, the territory level and the landscape level Moreover, relationships between the abundance of alders and hazel grouse were found at two additional levels of scale the local patch level and the biogeographic region level This agreement of the results from four levels of scale strongly suggested that the abundance and distribution of alder was a major factor limiting hazel grouse winter territories within dense Norway spruce Picea abies forests in the boreal zone of Fennoscandia Alder was relatively uncommon and exhibited a clumped dispersion pattern at the local and landscape scales, being associated with wet and rich soils The close relationship to alder implies that hazel grouse winter habitats, even in natural forests, also should be distributed patchily Hazel grouse may select the catkins and buds of alder because it is a very nutntous food source, and small species, such as the hazel grouse, require more nutritious food than larger species     

Fine‐scale habitat use during the non‐breeding season suggests that winter habitat does not limit breeding populations of a declining long‐distance Palearctic migrant

For migrant birds, which habitats are suitable during the non‐breeding season influences habitat availability, population resilience to habitat loss, and ultimately survival. Consequently, habitat preferences during winter and whether habitat segregation according to age and sex occurs directly influences migration ecology, survival and breeding success. We tested the fine‐scale habitat preferences of a declining Palearctic migrant, the whinchat Saxicola rubetra, on its wintering grounds in west Africa. We explored the influence of habitat at the territory‐scale and whether dominance‐based habitat occupancy occurs by describing the variation in habitat characteristics across wintering territories, the degree of habitat change within territories held throughout winter, and whether habitat characteristics influenced territory size and space‐use within territories or differed with age and sex. Habitat characteristics varied substantially across territories and birds maintained the same territories even though habitat changed significantly throughout winter. We found no evidence of dominance‐based habitat occupancy; instead, territories were smaller if they contained more perching shrubs or maize crops, and areas with more perching shrubs were used more often within territories, likely because perches are important for foraging and territory defence. Our findings suggest that whinchats have non‐specialised habitat requirements within their wintering habitat of open savannah and farmland, and respond to habitat variation by adjusting territory size and space‐use within their territories instead of competing with conspecifics. Whinchats show a tolerance for human‐modified habitats and results support previous findings that some crop types may provide high‐quality wintering habitat by increasing perch density and foraging opportunities. By having non‐specialised requirements within broad winter habitat types, migrants are likely to be flexible to changing wintering conditions in Africa, both within and across winters, so possibly engendering some resilience to the rapid anthropogenic habitat degradation occurring throughout their wintering range.     

Overlapping territory of the benthophagous cichlid fish, Lobochilotes labiatus, in Lake Tanganyika

Synopsis Feeding territories do not usually overlap in the same fish species. We studied overlapping territories and feeding behaviours of a benthophagous cichlid fish Lobochilotes labiatus Boulenger in a coastal area of Lake Tanganyika. Forty-four individuals of both sexes, 6–31 cm in total length, maintained territories in a 21 m × 25 m area. These could be regarded as feeding territories. The territories of similar-sized owners (usually different by less than 5 cm) did not overlap each other, but those of different-sized owners overlapped widely. Aggressive interactions were rarely observed between fish distinctly different in body size. Both large and small fish took benthic animals of the same kinds and of similar size. In contrast, the size of foraging sites (crevices) was different between them: the large fish foraged at large crevices and small fish at small crevices. This partitioning of foraging sites may enable the overlap of territories in this benthivore.     

Can Experience Alter the Avian Annual Cycle? Results of Migration Experiments with Indigo Buntings

Field experiments were conducted during 2 years testing whether premature release on their familiar, perennial breeding territories would cause indigo buntings (Passerina cyanea) to delete spring migration from their annual cycle. In the first year, male buntings were captured on their breeding territories in summer and held indoors for the winter on the photoregime that they would have encountered in nature as fall migrants and winter residents. The following spring they were released at the time buntings begin spring migration from the subtropics. Half were released on their breeding territories, to which they would normally have returned; half were released far to the south. Some of the males released on their territories remained and passed into breeding condition without having migrated, while some of those released to the south returned north to their territories. The results suggest that endogenous or photoperiodic mechanisms controlling the timing and occurrence of migration in this species can be overridden by experience. In the second year we tested alternative explanations for these results. Our second year's results seem to indicate (1) that birds that deleted migration in year one did not do so because of unfavourable weather and (2) that the birds that returned to their breeding sites in year one were actually migrating and not simply retracing their outward journey.     

THE SOCIAL BEHAVIOUR OF THE WHITE WAGTAIL MOTACILLA ALBA ALBA WINTERING IN ISRAEL

White Wagtails Motacilla alba wintering in Israel are partly territorial, mostly around human habitations, and partly live in flocks around temporary food sources. Individual birds may spend part of the season (or the day) in the territory and the other part with a flock. Experiments with artificial distribution of food, in a natural habitat, brought about a change from flocking to territorial behaviour. Preliminary observations suggest that in the natural situation the pattern of food distribution may be the proximate factor which regulates the birds' behaviour, by determining whether they have to fight for their food. Pairs are formed on many territories, and may last for long or short periods. Pair formation is initiated by females, who when seeking food appease the territorial males and are able to stay with them on their territories. Females also manifest territorial behaviour. Although pairing in winter territories is similar, in the behaviour involved, to sexual pairing, it is very unlikely that winter pairing continues into, or influences, pairing for breeding. It is suggested that the function of winter pair formation is that it allows two birds to exploit one territory, and that the main advantage is to the female which is the subordinate bird of the pair. This kind of pair-formation may be analogous to non-breeding group territories reported in some other birds.     

Effect of Sky Lark plots and additional tramlines on territory densities of the Sky Lark Alauda arvensis in an intensively managed agricultural landscape

Capsule: Sky Lark plots and additional tramlines increase Sky Lark Alauda arvensis territory densities in winter crops.

Aims: To analyse the effects on Sky Lark territory density of Sky Lark plots and additional tramlines in winter cereals and oilseed rape.

Methods: We mapped Sky Lark territories on fields with Sky Lark plots or additional tramlines as well as on adjacent control sites, from 2010 to 2013 in Saxony, Germany, where agricultural land use is intensive, dominated by winter-sown crops and takes place in large fields.

Results: In test sites with Sky Lark plots, 5.6 and 3.1 territories per 10?ha were found in the early (April/May) and late periods (June/July) respectively, compared to 3.3 and 1.4 territories per 10?ha in control sites. Sky Lark territory densities in fields with additional tramlines were 1.6 times higher in the early period (4.2 versus 2.6 territories per 10?ha) and 2.2 times higher in the late period (3.6 versus 1.6 territories per 10?ha).

Conclusion: Sky Lark plots and additional tramlines improve large fields for the Sky Lark and have the potential to increase the Sky Lark population.     

Possible relationships between morphology,territory quality,and skin color of American Kestrels1

ABSTRACT Carotenoid‐based coloration of skin and plumage has been found to be correlated with individual quality in many species of birds during the breeding season. However, less is known about the possible role of these signals during the nonbreeding season, particularly among nonpasserines that defend winter territories. American Kestrels (Falco sparverius) are sexually dimorphic raptors that defend winter territories and possess carotenoid‐based morphological features known to be correlated with individual quality. Much is known about winter territory use and habitat segregation by male and female kestrels, but possible relationships among morphological features, individual quality, and habitat quality have not been examined. Our objective was to examine possible relationships between morphology, territory quality, and skin color of American Kestrels. Male kestrels had brighter skin than females, and the skin color of male kestrels was positively correlated with size (wing chord and tail length) and territorial quality (hunting territories with less canopy and more grass cover). No such relationships were found for female kestrels. Skin color appears to be an honest indicator of quality for male American Kestrels and may serve both intersexual (territory acquisition) and intersexual (mate choice) functions during the breeding and nonbreeding seasons.     

Conflicting Territory Use in Males and Females of a Monogamous Ungulate,the Kirk's Dikdik

In monogamous mammals it is often unclear why males do not defend larger territories to attract more than one female. I investigated the territoriality of the monogamous Kirk's dikdik, Madoqua kirki, a dwarf antelope, in which food resources increase with territory size and some males defend enough resources for more than one female. Yet, all males are paired monogamously. When males were removed from small territories, their female partners spent more time outside of their territories than females in large ones. When females were removed, their male partners almost never left. Pairs in small territories spent more time together than pairs in large ones. Paired males left mostly together with their females, apparently not on their own initiative. Presumably because females in small territories left more often, their males spent more time outside in the female's company than males in large territories. I argue that males in smaller territories can keep better track of their females and that they can effectively reduce their females' time outside. Male intrusion pressure was unrelated to territory size, but it increased in the presence of unguarded females. If large territories decrease the ability to mate guard, and if unguarded females attract competing males, then defending large territories may be uneconomical, even it they could attract more than one female. On the other hand, territories must be large enough to satisfy the requirements of a single female.     

Patterns in departure phenology and mass gain on African non‐breeding territories prior to the Sahara crossing in a long‐distance migrant

Afro‐Palaearctic migrants are declining to a greater degree than other European species, suggesting that processes occurring in Africa or on migration may be driving these trends. Constraints on food availability on the wintering grounds may contribute to these declines but little is known about when and where these resource constraints may occur. Sufficient resources are particularly important prior to spring migration, when migrants must cross the Sahara Desert. We examined mass gain and departure phenology in a long‐distance Palaearctic passerine migrant to determine the degree to which pre‐migratory fattening occurs in their long‐term non‐breeding territories in the Guinea Savannah region of Africa. We monitored 75 Whinchats Saxicola rubetra for departure from their non‐breeding territories in one spring, and analysed mass data of 377 Whinchats collected over three non‐breeding seasons plus 141 migrating Whinchats caught in April over 8 years, all within the same few square kilometres of human‐modified Guinea Savannah in central Nigeria. Whinchats left their winter territories throughout April, with males departing on average 8 days earlier than females. However, there was no evidence that time of departure from territory was linked to age, body size or mass at capture. Whinchats departed their territories with a predicted mass of 16.8 ± 0.3 g, considerably less than the c. 24 g required for the average Whinchat to cross the Sahara directly. Comparing departure dates with arrival dates in southern Europe showed a discrepancy of at least 2 weeks, suggesting that many Whinchats spend considerable time on pre‐migratory fuelling outside their winter territory prior to crossing the Sahara. Overwintering birds gained mass slowly during February and March (0.03 g/day), and non‐territorial or migrating birds at a much higher rate in April (at least 0.23 g/day), with up to 20% of migrating Whinchats in April potentially having sufficient fuel loads to cross the Sahara directly from central Nigeria. Our results suggest that most Whinchats leave their winter territories to fatten up locally or, possibly, by staging further north, closer to the southern limit of the Sahara. Resource constraints are therefore likely to be particularly focused in West Africa during mid‐April and possibly at staging areas before the crossing of the Sahara Desert.     

Male foraging avoidance in female feeding territories in a harem polygynous cichlid in Lake Tanganyika

We studied foraging site partitioning between the sexes in Neolamprologus tetracanthus, a shrimp-eating Tanganyikan cichlid with harem-polygyny. Females maintained small territories against heterospecific food competitors within large territories of males, foraging exclusively at the inner side of their own territories (foraging areas). Males fed as frequently as females in their own territories, but mostly outside female foraging areas, although they frequently entered female territories and repelled food competitors from the territories. Soon after removal of the resident females, however, harem males, as well as many food competitors, invaded the vacant territories and intensively devoured prey of female foraging areas. This indicates that although female foraging areas appear to contain more food than outside the areas, harem males refrained from foraging there when the resident females were present. We suggest that harem males will attempt to keep female foraging areas in good condition, whereby they may get females to reside in male territories and/or promote female gonadal maturation.     

Assessing the importance of artificial nest‐sites in the population dynamics of endangered Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas using stochastic simulation models

Habitat availability might be the most important determinant of success for a species reintroduction programme, making investigation of the quality and quantity of habitat needed to produce self‐sustaining populations a research priority for reintroduction ecologists. We used a stochastic model of population dynamics to predict whether attempts to improve existing breeding territories using artificial nest platforms improved the population growth rate and persistence of a reintroduced population of Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas. We further assessed whether the creation of new territories, i.e. conversion of entire areas to suitable habitat and not simply the erection of nest platforms, would lead to a subsequent increase in the nesting population. Our model was able to reproduce several characteristics of the wild population and predicted the number of breeding pairs per year strikingly well (R² = 0.97). Simulations revealed that the addition of nest platforms improved productivity such that the population would decline to extinction without them but is stable since their installation. Moreover, the model predicted that the increase in productivity due to nest platforms would cause the population to saturate available breeding territories, at which point the population would contain a moderate proportion of non‐territorial birds that could occupy territories if new ones become available. Population size would therefore be proportional to the increase in available territories. Our study demonstrates that artificial nest‐sites can be an effective tool for the management of reintroduced species.     

Wind conditions experienced during the day predict nocturnal restlessness in a migratory songbird

A variety of methods have been used to study the relationship between wind conditions and departure decisions of migrant birds at stopover sites. These methods are either costly or suffer from inaccuracy in determining whether or not an individual has resumed migration. Here we present a novel and simple approach to studying the relationship between wind conditions and departure likelihood. Northern Wheatears Oenanthe oenanthe caught during stopover were temporarily caged to measure their nocturnal migratory restlessness, which is an accurate proxy for their individual departure likelihood. We then related the degree of nocturnal restlessness to wind conditions prevailing at the time of capture. Confirming the general pattern from previous studies of departure, the intensity of nocturnal migratory restlessness, and hence departure likelihood, increased with increasing wind support towards the migratory goal. This suggests that approximating the propensity to depart by measuring nocturnal migratory restlessness is a reliable way to study the effect that wind conditions experienced during stopover has on the departure decision of migrants. Our study also shows that nocturnal migrants possess the ability to use information gathered during the day for their departure decisions at night. Because measuring migratory restlessness is straightforward and inexpensive, our approach is ideally suited to test hypotheses regarding spatio‐temporal variation in wind selectivity in migrating birds.     

Social organization and spawning in the Atlantic sharpnose puffer,Canthigaster rostrata (Tetraodontidae)

Synopsis Social organization and spawning in the sharpnose pufferCanthigaster rostrataere studied on a reef in the San Blas Islands, Panama. Sexes were dimorphic. In mixed coral and rubble habitat, females defended territories against other females and small males. From one to six female territories were included within the territories of certain large males. These haremic males visited their females and patrolled their territories throughout the day. Smaller, non-haremic males occupied territories or home ranges within or adjacent to those of haremic males or were wanderers. Spawning between a haremic male and a territorial female occurred within the female's territory. The female prepared an algal nest into which demersal eggs were deposited. There was no parental care. Eggs were spherical, translucent, and measured approximately 0.66 mm in diameter. Larvae were about 1.4 mm TL and closely resembled those of other species ofCanthigaster.     

The wintering of migrant Dunnocks Prunella modularis in two Mediterranean habitats after fire

Migrant Dunnocks Prunella modularis are common winter visitors to the Mediterranean area. In a burnt forest, Dunnocks were present from October to April. They occupied definite individual home ranges of 0.18 ha on average (n = 83), at a density of 30 birds/10 ha in the fifth winter and 18 birds/10 ha in the sixth winter following a fire. Birds used visible posts and uttered ‘tseep’ calls often. Counter-calling was particularly frequent in the winter with the highest population density. In a burnt maquis, Dunnocks showed return rates (15%) and median recapture distances (62.5 m) not significantly different from those of territorial wintering Robins Erithacus rubecula. We suggest that Dunnock ranges can be regarded as ‘feeding territories’, promoted by an abundant, predictible and renewable food supply of rock-rose Cistus spp. seeds, characteristic of early Mediterranean successions. Ownership might be proclaimed by ‘tseep’ calls, recalling the behaviour of female Dunnocks during prebreeding territorial conflicts. Further research using colour-ringed birds may confirm Dunnock winter territoriality, exceptional for a migrant and mostly granivorous passerine.     

Spatial and Temporal Variability in Territoriality of a Tropical Benthic Damselfish on a Coral Reef (Réunion Island)

The relationship between length of individual Stegastes nigricans and size of the territory that they defend, and both the spatial and temporal variation in territoriality were investigated monthly on a fringing coral reef of Réunion Island over the course of one year. Length of individual S. nigricans was correlated positively with size of the territory. Most small individuals were found separate from adults, in areas with low algal turf cover. This is probably due to strong intra-specific competition for access to algal food resources and shelter availability, and/or differences in habitat preference. Both abundance of individuals and surface defended showed seasonal fluctuations. Densities were slightly higher in austral summer than in winter, and the surface defended by individuals larger than 8cm increased in winter. A permanent redistribution of territories also occured between individuals over time.