Temporal changes in the breeding ecology of European Turtle Doves Streptopelia turtur in Britain, and implications for conservation

The migratory European Turtle Dove Streptopelia turtur has undergone a 69% decline in population size and a 25% contraction in breeding range in Britain over the last 30 years. An investigation of the breeding ecology of this summer visitor was undertaken in 1998–2000 at two study sites in East Anglia, England. The only previous study of Turtle Dove reproduction in Britain provided pre-decline data for comparison with the current situation in a modern agricultural environment. Territory sizes ranged from 1.91 to 3.08 ha, were established in areas with scrub, hedges and woodland and contained less cropped land than expected from its availability. The majority of nests were sited 1–3 m above ground level within thorny bushes, particularly Hawthorn Crataegus monogyna . Nests found by radiotelemetry were significantly higher above ground level and were found in greater numbers than expected in woodland and coniferous trees than those found by cold searching, which were lower and found predominantly in hedges and thorny bushes. Turtle Dove nest success rate averaged 53% during incubation and 65% during the nestling stage, so that only 35% of nests successfully produced young. A comparison with data collected during the 1960s showed that Turtle Doves today have a shorter breeding season and consequently produce about half the number of clutches and young per pair than formerly. A simple simulation model suggested that the reduction in productivity alone would lead to a population decline of 17% per annum. This study suggests that the recovery of Turtle Doves in Britain is dependent upon the provision and sympathetic management of nesting and foraging habitats. The current arrangements for set-aside and agri-environmental schemes provide the framework for delivering these requirements.     

Changes in sexual selection resulting from novel habitat use in the sand goby

Resource availability may determine local breeding systems and may also vary locally between different habitats, affecting the way individuals distribute themselves between these habitats. For nest-breeding fishes, nest site availability is a crucial resource that has been found to affect local sexual selection regimes and thus breeding systems. In this study, we compared the availability and size distribution of nest sites and their consequences for habitat preference, fish distributions and the breeding system in sand gobies ( Pomatoschistus minutus ) breeding in two different habitats. The usual breeding sites of sand gobies are shallow sandy beaches, but here we report their breeding in a novel environment, on rocky bottoms. We found obvious differences between the two habitats. The density of occupied nests was nearly 50 times higher in rock habitat than on sand bottoms. However, competition for nest sites was stronger on sand; nearly all natural nest sites found were in use and empty nest sites were occupied at a much higher rate on sand than in rock habitat. In addition to the numerical differences, nests were larger and contained more eggs in rock habitat than in sand habitat. Moreover, we found significant habitat-specific differences in fish size distribution. The intensity of intrasexual competition as a result of the degree of nest site availability explains the observed patterns within the habitats, but not between them. These habitat-related differences are better explained by the larger average size of nests on rocky bottoms. The effect of nest size on habitat preference was confirmed experimentally by laboratory experiments. When nest size did not differ between the habitats, gobies originating in the two environments showed an equal preference for the sand habitat.     

Home range sizes in the Wood mouse Apodemus sylvaticus: habitat, sex and seasonal differences

This paper investigates home range sizes in the Wood mouse Apodemus sylvaticus in two habitats of differing productivity; deciduous woodland and sand-dunes. The ranges were measured by radio-telemetry. The home ranges in the sand-dunes were approximately circular whilst those in the woodland were much more complex in shape. At all seasons, the ranges in the sand-dunes were much larger than those in the woodland. Male ranges were larger than female ranges, especially so in the breeding season. In the non-breeding season, sexual differences in range sizes could be accounted for by the greater energy requirements of the larger males. During the breeding season, males expanded their ranges, probably in an attempt to find receptive females.     

The anatomy of the interspecific abundance–range size relationship for the British avifauna: I. Spatial patterns

Data from the British Trust for Ornithology Common Birds Census and two atlases of breeding birds were used to examine the form of the interspecific abundance–range size relationship for the British avifauna. The relationship is positive for both farmland and woodland habitats and over two different periods, with some evidence of curvilinearity, using either proportion of occupied sites or numbers of occupied 10 × 10 km squares as measures of range size, and mean density at occupied sites as a measure of abundance. A log-linear plot gives the highest correlation. The relationship is stronger if based on maximum local densities than if based on average densities, but there is no relationship using minimum local densities. Relationships based on abundances at individual sites are uniformly positive for all sites, although the relationships for many sites also show evidence of curvilinearity, especially when range size is measured as the proportion of occupied sites. Species show significant concordance in their rank abundances across sites. We discuss some implications of these results.     

Factors influencing patch occupancy and within‐patch habitat use in an apparently stable population of Willow Tits Poecile montanus kleinschmidti in Britain

Capsule Birds selected younger woodland patches with fewer conifers and higher soil moisture content; within these patches, they selected areas with higher vegetation cover at 2–4 m, and less bracken.

Aims For an apparently stable population, to investigate habitat differences between occupied and unoccupied woodland patches and habitat selection within occupied woodlands.

Methods We surveyed woodland patches for breeding Willow Tits in April 2006 in an area with an apparently stable population. Habitat was measured at points spread throughout each woodland patch and at points where Willow Tits were located. We compared habitat between occupied and unoccupied sites. In addition, within occupied sites, we examined habitat differences between Willow Tit locations and the points spread throughout the wood.

Results We surveyed 65 woodland patches, of which 29 were occupied. Willow Tits were more likely to be found in deciduous woodland that was younger and had higher levels of soil moisture. Probability of occupancy fell from 60% for woods aged 20–25 years to only around 15–30% for woods aged over 80 years. Within occupied woods, Willow Tits were more likely to be found in areas with more vegetation cover at the 2–4 m level and in areas with less bracken.

Conclusions Habitat management for Willow Tits should involve provision of young woodland patches with moist soils. Changes to the age structure and/or the soil moisture content of woods may be implicated in the dramatic decline of Willow Tits in Britain.     

The reproductive success of Blackbirds Turdus merula in relation to habitat structure and choice of nest site

The reproductive success of a population of Blackbirds Turdus merula occupying farmland and woodland was studied over 3 years to investigate the effects of habitat on breeding success. Territory distribution was patchy in both farmland and woodland; some areas were unoccupied, while other areas were occupied at variable densities. Habitat structure appeared to influence occupation: the index of habitat complexity ("cover score") was higher in occupied areas than in unoccupied areas and high-density territories had higher cover scores than low-density territories. However, habitat structure had no significant effect on reproductive success because the cover scores of territories where pairs were successful did not differ significantly from those of territories where there were no successful breeding attempts. There was no evidence of differential mortality rates in adults according to habitat. The height, bulk and exposure of c. 430 nests were measured to determine the effect of nest and nest-site characteristics on reproductive success. Nest exposure was the only feature that differed between successful and failed nests, successful nests being less exposed than failed nests. The major cause of breeding failure was nest predation, but the effect of nest exposure operated only during the laying and incubation period and not during the nestling period. The significance of habitat structure for variation in population densities between habitats is discussed.     

Correlates of Common Buzzard Buteo buteo density and breeding success in the West Midlands

Buzzard density and breeding success in relation to habitat and Rabbit Oryctolagus cuniculus abundance was studied in the West Midlands from 1994 to 1996. We found densities of 81 and 22 territorial pairs per 100 km² in two areas 40 km apart; the former is the highest density yet recorded in Europe. High Buzzard breeding densities were associated with high proportions of unimproved pasture and mature woodland within estimated territories. Buzzards laid earlier clutches at lower altitudes and with high proportions of unimproved pasture close to nests. Large clutches and high numbers of fledged young were associated with high Rabbit abundance close to nests. Most nest failures occurred during incubation and were probably mainly due to corvid predation. Brood reduction was associated with low proportions of deciduous woodland close to nests and small clutch sizes, although the causes of chick mortality were uncertain. Rabbits were the main prey item found at nests with passerines, especially young corvids, also appearing frequently.     

A comparative study of the ecology of woodmice Apodemus sylvaticus in two contrasting habitats: deciduous woodland and maritime sand-dunes

The woodmouse is a characteristic rodent of deciduous woodland but also occurs in a wide variety of othe habitats. This paper describes the comparative ecology of woodmice living in two habitats of markedly different productivity; deciduous woodland and a maritime sand-dune system.
The diets of the two populations were quite different; woodland mice ate mainly seeds whilst those on the dunes subsisted on invertebrates, particularly Coleoptera.
Population densities in the woodland were higher than those on the dunes. In contrast, home range sizes were much larger on the dunes.
Mice living in the two habitats exhibited different patterns of activity. The dune animals left their nests earlier in the evening and they were active for longer each night.
It is argued that all of these differences between the two populations are due to differences in food availability in the two habitats.     

Breeding success of Spotted Flycatchers Muscicapa striata in southern England – is woodland a good habitat for this species?

The UK population of the Spotted Flycatcher Muscicapa striata has declined markedly in the last 30 years but there have been few recent studies of the species. This study examined the relationship between nest success and the predominant habitat type around Spotted Flycatcher nests in two contrasting areas of England. A breeding population in eastern England, a region where numbers of Spotted Flycatchers are known to have decreased dramatically in recent decades, was compared with another in southwest England, where numbers have remained stable or even increased. Whilst there was no difference in breeding success between the two study areas, there were significant differences between habitats, with garden nests more successful than those in farmland or woodland, at both egg and chick stages. Estimates of productivity per nesting attempt were also lower in farmland and woodland, with nests in gardens fledging twice as many chicks as those in either woodland or farmland. The proximate cause of lower success in farmland and woodland was higher nest predation rates during both egg and chick stages. In terms of nesting success, farmland and woodland appear to be similar in quality for this species, but both appear to be suboptimal habitats when compared with gardens, providing evidence of a problem on the breeding grounds for this species, in at least these two habitats.     

Chimpanzee nest distribution and site reuse in a dry habitat: implications for early hominin ranging

This paper reports on a 20-month study of chimpanzee nesting patterns in Issa, Ugalla, western Tanzania. Ugalla is one of the driest, most open, and seasonal habitats where chimpanzees are found. The methods used were ethoarchaeological, as the chimpanzees were not habituated and behavioural observations were rare. Systematic data on the spatial and temporal distribution of nests are presented. Places with no nests at the beginning of the study, despite being suitable for nesting, were used as controls. Similar to other chimpanzee study sites, nests were highly concentrated in some parts of the landscape. Issa chimpanzees preferred to nest on slopes. They extensively used the woodland vegetation type of their habitat for nesting throughout the annual cycle. Ninety percent of nest sites were used repeatedly throughout the study period, but none of the control places had nests during this period. The results indicate that chimpanzees ranged more widely during the dry season, when food abundance was lowest, food was available mainly in open vegetation types, and when drinking water was restricted to a few sources. Early hominins in similar habitats may have followed the ranging strategy of Issa chimpanzees. As with a previous study, the distribution of nests was spatially similar to archaeological distributions in early hominin sites. Hominin topography and vegetation type preferences may be misrepresented in the archaeological record. Nest sites may have been the antecedents of carcass processing sites.     

Ranging behaviour and time budgets of male wood mice Apodemus sylvaticus in different habitats and seasons

Radiotelemetry was used to measure the range areas, activity patterns and time budgets of 21 adult male wood mice (Apodemus sylvaticus) between May 1991 and August 1992. The study investigated variation in range, total distance travelled, speed of movement and time budgets between wood mice in the nonbreeding and breeding seasons in a deciduous woodland (n = 8 and 6 respectively). We also examined habitat differences by estimating these same parameters for wood mice inhabiting maritime sand-dunes in the breeding season (n = 7). Insufficient males of an appropriate mass for radiotracking were captured to study the sand-dune mice in the nonbreeding season. Significant variation was found across both season and site. In the breeding season, in woodland, range areas were 5 times larger than during the nonbreeding season. Wood mice on the sand-dunes exploited ranges 28 times greater than their woodland counterparts. The pattern of variation in range area was parallelled by significant differences in total distances and average speeds travelled per night. Diurnal activity, c. 60 min day⁻¹, was frequently recorded, at both sites, but only, in the breeding season, which was attributed to the need to forage in order to maintain energy balance. The comparatively lower availability of food on the sand-dunes was considered the main factor explaining the greater range area, total distance moved, speed travelled and level of activity of animals at this site. Received: 11 September 1995 /Accepted: 12 August 1996     

BREEDING SEASONS OF BIRDS IN DECIDUOUS WOODLAND AT ZIMBABWE,RHODESIA, FROM 1970 TO 1974

Vernon, C. J. 1978. Breeding seasons of birds in deciduous woodland at Zimbabwe, Rhodesia, from 1970 to 1974. Ostrich 49:102-115.

The birds in Brachystegia woodland bred in the spring and 98% of 1645 breeding records occurred between September and November. 90% of the records, and 43 of the 71 breeding species, were of insectivorous passerines. The breeding seasons of individual species lasted for between less than two months to more than three months, and their peak breeding periods varied between early September and the middle of October. The breeding season started earliest in 1974 and latest in 1973, and the start of two species was related to the timing of leaf emergence of the dominant tree in the woodland and to rainfall the previous rainy season. Food supply may be the proximal factor influencing the onset of breeding.     

Nest site selection and predation driven despotic distribution of breeding long-eared owls Asio otus

Long-eared owls Asio otus do not build their own nests. They occupy old corvid nests in either coniferous or deciduous trees. In my study area owls favoured coniferous over deciduous trees for nesting and occupied nest sites in that order. Comparing overall breeding output, I found no difference between the two kinds of nest sites, but among early nests there was a higher proportion of unsuccessful nests in deciduous trees. This difference was due to differences in predation rate, indicating that the owls' pattern of nest site occupation followed predictions from the ideal despotic distribution model. I also show that, due to a seasonal change in habitat quality, predator driven despotism, although present, can be well masked and hence difficult to detect.     

Assemblages of terrestrial isopods (Isopoda, Oniscidea) in a fragmented forest landscape in Central Europe

Terrestrial isopods were collected in 13 forest fragments differing in area (within the range of 0.1 and 254.5 ha), shape and composition of forest vegetation (thermophilous oak, mesophilous oak-hornbeam, thermophilous oak-hornbeam, acidophilous oak, basiphilous oak, beech oak-hornbeam, moist mixed deciduous forest, plantations of deciduous and coniferous trees), all situated in the Český kras Protected Landscape Area, Czech Republic, Central Europe. Number of sites sampled in each fragment of forest depended on its size and ranged from 1 to 7. Altogether 30 sites were sampled. Soil samples (5 per site collected twice a year) and pitfall trapping (5 traps per site in continuous operation throughout a year) during 2008–2009 yielded a total of 14 species of terrestrial isopods. The highest densities and highest epigeic activities of terrestrial isopods were recorded in the smallest fragments of woodland. Although a wider range of habitats were sampled in the larger fragments of woodland there was not a greater diversity of species there and the population densities and epigeic activities recorded there were lower. Porcellium collicola was most abundant in small fragments of woodland regardless the vegetation there. Armadillidium vulgare and Protracheoniscus politus were statistically more abundant in the larger fragments of woodland. The results indicate that forest fragmentation does not necessarily result in a decrease in the species richness of the isopod assemblages in such habitats.     

Breeding ecology of the Clay-coloured Robin Turdus grayi in lowland Panama

The breeding ecology of Clay-coloured Robins Turdus grayi was studied in 1979 in the former Canal Zone of lowland Panama. Two study areas were chosen close together, Summit Gardens (27-3 ha), an ecological island of habitat suitable for Clay-coloured Robin surrounded by forest, and Morgan's Gardens (3–6 ha), a similar island surrounded by deforested areas and settlements. Eighty-three active nests were found and checked. The breeding season lasted from 2 March to 21 June. In Morgan's Gardens the first broods were raised in the dry season and second broods in the rainy season; in Summit Gardens most broods started at the beginning of the rainy season. In comparison to the closely related Blackbird T. merula in Poland, Clay-coloured Robins build nests on isolated trees or bushes, usually in more conspicuous sites (interpreted as an anti-predator adaptation) and on flexible, horizontal branches off the main trunk. Over 45% of broods were destroyed by predators but other factors causing brood loss were negligible. Nests built on palms were considerably safer. In the dry season the predation rate was low (5%) and increased during the course of the rainy season. Unlike Blackbirds, Clay-coloured Robin nestlings were given a lot of fruit; their diet was diversified. Starvation occurred in 60% of nests although usually only the youngest nestling died. Breeding density in Morgan's Gardens at 50 pairs per 10 ha was much higher than in Summit Gardens at 15>8 pairs per 10 ha. Breeding losses were lower, the nestlings were fed more fruit, the average nestling weight was lower and the production of fledglings per breeding pair was twice as high in Morgan's Gardens. It was concluded that a strategy of settling in a rather overpopulated place with hard foraging conditions but lower predation was better than settling in a area with a better food supply but higher predation.     

The breeding ecology and diet of the Hobby Falco subbuteo in southern England

Brecding densities, nest spacing, breeding habitat, productivity and diet are compared for Hobbies Falco subbuteo in the New Forest (heathland and largely coniferous woodland), river valley farmland and largely cultivated chalk downland. Regular spacing of nests was characteristic of the three areas. The New Forest had the highest density and lowest mean nearest neighbour distance for nests. Nest areas tended to be traditional. A high proportion of clutches were laid in disused nests of Carrion Crows Corvus corone which favoured the crowns of Scots pine Pinus sylvestris. Except on downland, the availability of such sites is unlikely to provide a constraint on Hobby distribution. In the New Forest, woodland clearings and valley mires were a feature of nest territories. There was no evidence of a habitat-related difference in fledging success.
Division of labour between sexes is marked. The male is responsible for provisioning the female throughout most of the breeding season as well as the young. During the incubation period many woodland passerines were taken but when feeding nestlings Hobbies tended to specialize on Swallows Hirundo rustica , House Martins Delichon urbica and, where they had access to more urban areas, Swifts Apus apus. By breeding relatively late, Hobbies take advantage of the availability of the juveniles of such prey on which to feed their young. Large insects supplemented the diet before egg-laying and when the Hedged young were learning to hunt.     

Foraging flight distances as a measure of parental effort in blue tits Parus caeruleus differ with environmental conditions

Life-history theory predicts that parental effort in nestling provisioning is optimised in relation to the quality of individuals and/or their habitat. We studied the investment of breeding pairs of blue tits Parus caeruleus for their reproduction during three breeding seasons in deciduous (high quality) vs. mixed (low quality) habitats in order to quantify to what extent habitat quality affects parental effort. Parental effort (costs) was related to their feeding rates and flight distances during foraging. In the deciduous habitat flight distances between nest and foraging patch were shorter than in the mixed habitat (22 m and 40 m, respectively), but the feeding rates did not differ between the habitats. The total flight distance per breeding pair from the first day after hatching until the 17th day of the nestling period was about half of the distance observed in the mixed habitat (375 km and 674 km, respectively). As the quality of fledglings did not differ between habitats, the higher number of fledglings per brood reflects better rewards per foraging trip in the deciduous than in the mixed habitat. Considering the parental foraging effort (costs) and, the quality and number of offspring (benefits), the benefit-cost-ratio was 2–3 times higher in the deciduous than in the mixed woodland.     

Patterns of roost site selection and use by Southern Ground-Hornbills in north-eastern South Africa

Different habitats may be used for the needs of various aspects of an animal’s life. Southern Ground-Hornbill Bucorvus leadbeateri groups announce their presence within year-round territories by calling at dawn from their overnight roost sites. Knowledge on ground-hornbill roosting habits is limited. Groups roost in large trees, apparently close to where they end up after daily foraging. We investigated patterns of roost site selection and use for four Southern Ground-Hornbill groups in the Associated Private Nature Reserves, north-eastern South Africa, based on data from GPS-satellite transmitters. The number of roost sites used per month averaged 15.4 ± 4.7 across all groups, indicating little evidence of strong preferences for specific sites. This number was least when groups were breeding, decreasing throughout the early wet season (October–December) and was lowest during the late wet season (January–March) when actively breeding groups frequently roosted close to the nest (54–83% of roosts <1 000 m of the nest). As might be expected, the mean monthly number of nights per roost peaked during the breeding season (December–January). Riparian habitats were preferred for roosting during the breeding season, whereas disturbed areas, as well as Combretumand mopane-dominated habitats were preferred during the dry non-breeding season. Adequate large trees not only for nesting, but also for roosting, particularly in riparian habitats, may therefore be an important and potentially limiting factor for the successful reproduction of Southern Ground-Hornbills.     

Causes of variable reproductive performance by Southern Ground‐hornbill Bucorvus leadbeateri and implications for management

Range occupancy of the cooperatively breeding Southern Ground‐Hornbill Bucorvus leadbeateri in South Africa has decreased by 65% in the last three generations and the effective management of the remaining populations is hampered by a lack of fundamental understanding of the factors determining reproductive performance. We examined the influence of social and environmental factors on the species' reproductive success in South Africa using data gathered from 23 groups over eight breeding seasons. Some groups had access to artificial nest‐sites, others did not. High rainfall (> 500 mm) over the breeding season led to a decrease in reproductive success, with groups being most successful in years when rain in the vicinity of the nest ranged from 300 to 500 mm. Groups breeding in natural nests were successful only when the proportion of open woodland surrounding the nest‐site was high. Those that bred in artificial nests, where overall breeding success was more than twice as high as those in natural nests, were less dependent on the availability of open woodland. Large groups (more than three birds) bred more successfully than groups comprising only two to three individuals. Group size, helper effects and rainfall cannot be managed to increase the productivity of Ground‐Hornbills but the fact that the availability of artificial nest‐sites and the amount of open woodland around the nest‐site both contribute positively to breeding performance identifies practical and simple management options for increasing the reproductive output of Southern Ground‐Hornbill populations.     

Territorial behaviour of the Robin Erithacus rubecula: the importance of vegetation density

Robin Erithacus rubecula territories were mapped in an isolated copse of mixed deciduous woodland. An index of vegetation density, measured at numerous randomly chosen sites within the copse, was found to be higher in areas occupied by Robins. Both vegetation density and territory area were compared with measures of breeding success. In all cases vegetation density was correlated with breeding success and territory area was not. Possible evolutionary advantages to defending areas with dense vegetation are discussed.