Numbers and distribution of Northern Lapwings Vanellus vanellus breeding in England and Wales in 1998

This paper presents the results of the BTO/RSPB survey of breeding Northern Lapwings Vanellus vanellus in England and Wales carried out in 1998. Numbers of breeding Lapwings and land-use types were recorded by volunteers in 1312 randomly selected tetrads using identical methods to those adopted in a previous survey in 1987. The results suggest a population of 62 923 breeding pairs (95% confidence intervals 55 268 to 74 499), representing a 49% decline in 11 years. The declines were greatest in southwest England and Wales, resulting in a marked contraction in range. Both arable and pastoral farmland was found to be important for Lapwings, highlighting their vulnerability to changes in a range of agricultural systems. Recent major changes in land management practices, including the switch from spring to autumn sowing and the conversion of rough to intensively managed, improved grassland is likely to have reduced both the area and the suitability of these habitats for Lapwings. Grassland within arable areas is known to provide important chick rearing habitat, and spring tillage with adjacent grassland was significantly more likely to hold Lapwings than spring tillage that did not abut grass fields. The prevalence of grass and spring tillage fields in close proximity has declined in recent years with the loss of traditional mixed farming and the polarization of pastoral systems in the west of Britain and arable in the east. The implications of these results for the conservation of Lapwings are discussed and it is recommended that, in the light of the scale of the decline recorded, Lapwings should be afforded much higher conservation priority in Britain than they are at present. The range contraction has resulted in high numbers being concentrated on reserves, highlighting the importance of sensitive management of these areas for this species. However, wider countryside measures should also be considered, such as specific options within agri-environment schemes, designed to enhance farmland habitats for Lapwings.     

Population dynamics and reproduction of Northern Lapwings Vanellus vanellus in a meadow restoration area in central Sweden

To investigate the effectiveness of a meadow restoration programme, we studied the relationships between population changes and environmental changes, return rates and hatching success in a population of Northern Lapwings Vanellus vanellus. The study was performed on mixed farmland (59 km²) in central Sweden, an area that underwent extensive meadow restoration between 1985 and 1994. The study included more than 2600 nests, supplemented with observations of 127 individually colour-ringed Northern Lapwings. The breeding population varied (2.7–5.3 pairs/km²), but showed no significant trend with time. The population increased in years with high spring flooding levels. Population size was unrelated to demographic factors (e.g. hatching success the previous year (14–50%), and return rate). Lapwings moved considerably between years and their nest site fidelity was unrelated to previous hatching success or other factors, suggesting that changes in habitat quality and migration between populations were important in regulating population size. Recent extensive meadow restoration did not seem to aid the Northern Lapwing population; birds continued nesting on tillage even though most nests were destroyed by farming activities. A relatively high relaying frequency improved hatching success, which was still lowest in the most preferred habitats (spring sown crops, total hatching success c. 30%). The few Northern Lapwings breeding in the least preferred habitats (meadows and cultivated grassland) had a better hatching success (> 70% total hatching success), suggesting that habitat selection was not determined by hatching success. From these results, recommendations are made for the management of Northern Lapwing (and associated species) populations on farmland.     

The effectiveness of volunteer nest protection on the nest success of Northern Lapwings Vanellus vanellus on Dutch arable farms

Clutches of ground‐nesting farmland birds are often destroyed by farming operations, resulting in insufficient reproductive success and subsequently declining populations. The aim of this study was to investigate whether volunteer nest protection can enhance nest success of ground‐nesting birds. The study compared nest success of protected and unprotected Northern Lapwing Vanellus vanellus nests over 2 years on arable farms in the Netherlands. Because of different crop management, nest success of ground‐breeding birds might differ between organic and conventional arable farms. The effectiveness of volunteer nest protection was therefore investigated on both farm types. Although nest protection significantly reduced nest loss due to farming operations, there were no significant differences in total clutch survival of protected and unprotected nests. However, sample sizes of unprotected nests, and protected nests on organic farms, were relatively small, which may have reduced statistical power. There were indications that protected nests were predated or deserted more often. We recommend exploring different ways to improve the effectiveness of volunteer nest protection through a further reduction of nest loss due to farming operations and predation.     

Habitat affects escape behaviour and alarm calling in Common Starlings Sturnus vulgaris

Animals should adapt their escape behaviour to both physical and social surroundings in order to maximize their probability of survival. Cover can be both obstructive, reducing the visibility of the surroundings and hindering escape, and protective, providing refuge. We investigated how the provision of cover (long grass) affected (1) the escape behaviour and (2) the alarm call behaviour of Common Starlings Sturnus vulgaris responding to a model hawk during a simulated attack. Starlings always retreated away from the predator and sometimes alarm-called. Their escape trajectory was close to the ground when escaping in long grass, which could be explained by either tall swards hindering take-off or such swards being used as protective cover. On short grass their escape trajectory was much steeper (> 45°). We also investigated the use of alarm calls in Starlings according to predictions arising from the costs and benefits to callers and receivers. Callers could benefit from using alarm calls through dilution or confusion if their use initiates flock departures, thus reducing their probability of being targeted. If there is no cost to the producer of alarm calls we predicted that detectors should call at all times to gain these benefits (i.e. irrespective of grass length), but if their use is costly we predicted that they would be used only when the benefits outstrip the costs. In this case we would predict that alarm calls would be given when other (visual) signals were impaired on long grass but not when they were effective on short grass. Starlings used alarm calls on long grass when visibility was reduced more frequently than on short grass, suggesting that calling has a cost to the producer. The contrasting escape strategies of Starlings in relation to a relatively small (10 cm) change in grass height demonstrates the potential importance of habitat structure in determining predation risk.     

Absence of effects of predator control on nesting success of Northern Lapwings Vanellus vanellus: implications for conservation

The control of generalist predator populations is increasingly adopted as a management tool to combat declines in ground‐nesting bird populations. However, compensatory predation by uncontrolled species frequently occurs, so determining the relative impacts of different predatory species, and hence the relative benefits of their control, can be difficult. Islands, with their reduced faunas, provide natural experimental units for investigating specific predator–prey interactions in detail. We studied Northern Lapwing Vanellus vanellus breeding success on an island where feral Ferrets Mustela furo and Hooded Crows Corvus cornix were subjected to trial control regimes over 2 years. In both years, Lapwing hatching success was >80%, with neither Ferret nor Crow control selected as important predictors. Fledging rates in both years were 0.7 young per pair, despite highly effective predator removal, although Crow control potentially resulted in compensatory predation by Common Ravens C. corax. Neither mustelid nor corvid control produced significant immediate benefits for Lapwings. This suggests that mesopredator release of mustelids in mainland situations is unlikely to be a consistent threat to Lapwing, and provides further evidence that declines in this species are unlikely to be tackled successfully through predator management alone.     

Nest success of Lapwings Vanellus vanellus on organic and conventional arable farms in the Netherlands

Increasing agricultural intensification has put farmland bird populations under great stress. Although organically managed farms tend to have higher densities of farmland birds than conventionally managed holdings, differences in crop management may also lead to differences in breeding success. With the use of agrochemicals prohibited on organic farms, weeds are controlled using mechanical methods that may pose a threat to ground-nesting birds. This study compares the territory densities and nesting success of the Lapwing Vanellus vanellus on organic and conventional arable farms in the Netherlands. Territory densities were generally higher on organic farms, although in one year nesting success was lower on organic than on conventional farms. This was caused by higher nest loss resulting from farming activities on organic farms. There were no differences in predation rates. The results of this study show that breeding Lapwings may face potential threats on organic farms. To sustain or enhance Lapwing populations on these farms, additional conservation measures should be implemented.     

Winter field use and habitat selection by Eurasian Golden Plovers Pluvialis apricaria and Northern Lapwings Vanellus vanellus on arable farmland

Eurasian Golden Plovers Pluvialis apricaria and Northern Lapwings Vanellus vanellus winter in large numbers on Britain's farmland. Previous studies in mixed farming areas showed pronounced preferences for permanent pasture, but increasing numbers of plovers winter in eastern Britain where arable farmland dominates. We show that an area of intensive arable farmland supported significant numbers of both species from October to February in the absence of large areas of pasture. Habitat use varied seasonally as the habitats present changed. Throughout winter, use of cereal crops matched their availability: plovers selected harrow in early winter, sugar beet stubbles in midwinter and other crops in late winter. Pastures were rarely used at any time of the year. Flocks occupied only a fraction of the available fields, concentrating most in large fields with open boundaries and where manure had been applied. Daytime feeding was more likely during cold days after nights with a new moon, short duration of moonlight or low-intensity moonlight. These results show that plovers are currently able to utilize intensive arable farmland but future changes in management, such as cessation of manure applications and reductions in sugar beet cropping, could have detrimental effects.     

The effects of improvement of upland, marginal grasslands on the breeding success of Lapwings Vanellus vanellus and other waders

Data on the breeding success of Lapwings Vanellus vanellus on unimproved and improved grassland, with comparative data for arable land, were obtained from a study on 760 Lapwing clutches. The study was undertaken in the Eden Valley, Cumbria, and Teesdale, Co. Durham, between 1985 and 1987. First clutches were larger on unimproved grassland with a mean of 3.73 eggs compared to 3.61 eggs on improved grassland. In contrast, replacement clutches were larger on improved areas (3.90 eggs) than on unimproved (3.47 eggs). On average, 40% of eggs laid on unimproved pastures hatched compared to only 17% on improved pastures. No significant difference in hatching success was found between unimproved and improved meadows with 32% and 22% of eggs hatching, respectively. Overall, 73% of unsuccessful first clutches were replaced on unimproved pastures, whereas on meadows and improved pastures combined, only 32% were replaced. Survival of small chicks was highest on unimproved areas. Production on unimproved areas was sufficient to replace adult losses and so maintain numbers, whereas on improved land production was too low to maintain existing breeding densities. Hatching success on unimproved areas was similar for the four species of wader considered. On improved areas, Redshank hatching success was relatively high, with 54% of pairs producing chicks, compared to 35% for Lapwing and 23% for Curlew.     

Against the trend: increasing numbers of breeding Northern Lapwings Vanellus vanellus and Black-tailed Godwits Limosa limosa limosa on a German Wadden Sea island

Capsule The increase in population sizes over the last 30 years cannot be explained by reproductive success.

Aims To establish whether the positive population trends are due to increasing and self-sustaining populations or to immigration.

Methods We studied the population development of breeding lapwings from 1971 until 2005 and of godwits from 1977 until 2005 on Wangerooge, a German Wadden Sea island. Both species increased significantly during the last three decades. For each species we used a logistic growth model to derive the reproductive output required to explain the past population development without assuming immigration. We compare the values derived by this model with empirical findings of reproductive output of the respective populations.

Results For neither lapwings nor godwits can empirical reproductive success explain the observed population development.

Conclusion Our results imply that the increase in breeding pairs of Northern Lapwing and Black-tailed Godwit on Wangerooge Island is not due to reproductive output. We propose that it is mainly caused by immigration onto the island.     

The timing and duration of moult in adult Starlings Sturnus vulgaris in east-central England

The timing and duration of primary moult were estimated for wild adult Starlings Sturnus vulgaris near Monks Wood in 1977-78, and for captive birds in 1999. The model of Underhill and Zucchini (1988) was modified to allow for a non-linear increase in the moult score, based on scores of captive birds. For wild birds, estimates of moult duration in 1977 and 1978 were 100 days and 98 days, with mean and standard deviation in start dates of 6 June and 7.3 days in 1977, and 2 June and 9.7 days in 1978. For captive birds, moult duration was 85 days, with mean and standard deviation of 31 May and 4.1 days. Differences between these estimates and those reported for other wild and captive Starling populations are discussed.     

Factors influencing the nesting success of Lapwings Vanellus vanellus and behaviour of Red Fox Vulpes vulpes in Lapwing nesting sites

Capsule Lapwing nest predation was negatively correlated to nest density, while Lapwing alarm duration in response to foxes was positively correlated with the number of Lapwing broods present.

Aims To identify factors affecting Lapwing nest predation and Red Fox search effort.

Methods Lapwing nest success was monitored at four sites in 1996, seven sites in 1997 and six sites in 1998. In 1997 we mapped the position of all Lapwing nests in order to determine distances between nests, and the proximity of linear features and potential avian predator perches to each nest. From April to June 1998 we carried out 199 hours of nocturnal observations at six Lapwing nesting sites using night vision equipment.

Results The risk of nest predation was significantly higher for more isolated nests. Nocturnal observations showed that of all the nocturnal predators, foxes were the most active at Lapwing nesting sites. However, fox search effort in Lapwing colonies was relatively low, averaging 57 s/ha per visit. Foxes spent significantly longer foraging near breeding Lapwings (measured as duration of alarm calls) when more broods were present. Fox search effort (s/ha per hour of observation) tended to be greater in areas of high waterbird density.

Conclusion The lack of positive density-dependent nest predation, the relatively low search effort of foxes near Lapwing nesting sites and the high nest success sometimes achieved in areas with foxes all suggest that Lapwing nest predation by foxes is ‘incidental’. Lapwing chicks are probably more vulnerable to predation by foxes than clutches.     

The effects of daylength and testosterone on the initiation and progress of moult in Starlings Sturnus vulgaris

The effects of daylength and of testosterone implants, before and after the beginning of moult, on the timing and rate of primary moult have been quantified. Female Starlings Sturnus vulgaris were moved from natural daylength in February to 13 h or 18 h of light per day (13L: 11D or 18L: 6D). Some of the birds on 18L: 6D were left on 18L: 6D throughout the experiment and others were transferred to 13L: 11D after 6 weeks, before moult had begun, or after 12 weeks, after moult had begun. Birds kept on 18L: 6D began to moult before birds kept on 13L: 11D, but the subsequent rate of moult was the same in both groups. A decrease in daylength before moult started slightly advanced the onset of moult. A decrease after moult had begun increased the speed of moult. Castrated male Starlings on 18L: 6D were given testosterone implants for different periods before or after the beginning of moult. Testosterone treatment which ended before moult would normally have started had little effect. Treatment extending beyond the normal start of moult considerably delayed or even prevented the onset of moult. Moult was arrested in birds which received testosterone after moult had begun. On removal of testosterone implants, moult began again from the point where it had stopped, but in some birds, all of the feathers which had been regrown recently were dropped again and regrown. These results are discussed in relation to the different patterns of moult seen amongst different species.     

Intraspecific nest parasitism in Starlings Sturnus vulgaris: effects of disturbance on laying females

Female Starlings Sturnus vulgaris that laid distinctive eggs at Worplesdon, Surrey, in 1988 and 1989 were made to desert their partially completed first clutches by removing their eggs part way through the laying sequence. Most of these Starlings continued to lay, but in other Starlings' nests, and most of them subsequently laid a replacement clutch that they reared themselves. Using estimates of the success of nests in the colony over 14 breeding seasons, it is concluded that intraspecific nest parasitism offers a means of maximizing annual chick production in the event of disturbance causing the loss of first-clutch eggs.     

The effects of delaying the start of moult on the duration of moult, primary feather growth rates and feather mass in Common Starlings Sturnus vulgaris

In many species of birds there is a close relationship between the end of breeding and the start of moult. Late-breeding birds therefore often start to moult late, but then moult more rapidly. This is an adaptive mechanism mediated by decreasing day lengths that allows late-breeding birds to complete moult in time. This study asked how these birds complete moult of the primary feathers more rapidly, and the consequences of this on the mass of primary feathers. Common Starlings Sturnus vulgaris were induced to moult rapidly in one of two ways. In the first experiment, one group was exposed to artificially decreasing photoperiods from the start of moult, whereas the control group remained on a constant long photoperiod. The second experiment was a more realistic simulation. Two groups were allowed to moult in an outdoor aviary. One group started to moult at the normal time. In the other, the start of moult was delayed by 3 weeks with an implant of testosterone. The duration of moult was significantly reduced in both the group experiencing artificially decreasing photoperiods and the group in which the start of moult was delayed. The faster moult rate was achieved by moulting more feathers concurrently. The rate of increase in length of each of the primary feathers, and their final length, did not differ between groups. The rate at which total new primary feather mass was accumulated was greater in more rapidly moulting birds, but this was insufficient to compensate for the greater numbers of feathers being grown concurrently. Consequently, the rate of increase in mass of individual feathers, and the final feather mass, were less in the rapidly moulting birds. A 3-week delay in the start of moult is not an unrealistic scenario. That this caused a measurable decrease in feather mass suggests that late-breeding birds are indeed likely to suffer a real decrease in the quality of plumage grown during the subsequent moult.     

The effect of a period of food restriction on gonad size and moult of male and female Starlings Sturnus vulgaris under constant photoperiod

The effects of food availability on the reproductive cycle and on the timing and duration of moult were investigated in first-year male and female Starlings Sturnus vulgaris under a constant photoperiod of 12 hours. A 20% lower body mass during the first 9 weeks of restricted feeding had a slight negative effect on testicular growth during the first 3 weeks of the experiment and delayed the onset of moult for 12 days after the return to ad libitum feeding conditions. No effects were found on changes of beak colour and moult duration of males. Females exposed to the shorter feeding time similarly showed a reduced body mass (21%) but compared with controls, did not differ in beak colour, in follicle growth, or in the onset and duration of moult. In contrast to males, body mass of the experimental females after the food restriction period remained lower for more than 6 weeks, compared to control birds. Females had a longer reproductive cycle and started moult later than males. The later an individual started to moult, the faster it moulted. Two females started to moult extremely late and did not moult their first primaries.
These results indicate that in male Starlings food restriction slightly affected the rate of photoinduced gonadal growth and the onset of postnuptial moult. These effects were not observed in females subjected to the same experimental conditions.     

Landscape effects on nest site selection and nest success of Northern Lapwing Vanellus vanellus in lowland wet grasslands

Capsule: Northern Lapwing Vanellus vanellus avoid nesting close to small woodland patches but nest predation rates do not vary with distance to woodland patches, either because risky areas are avoided or perceived nest predation risk does not reflect actual risk.

Aims: To explore the effects of woodland patches in wet grassland landscapes on nest distribution and success of Lapwings.

Methods: We quantified the effect of woodland patches on the distribution and outcome of Lapwing nests across four wet grassland sites by mapping nest distribution and monitoring nest outcomes.

Results: Lapwing nested significantly further from woods than expected by chance. Neither nest predation rates nor the probability of predation occurring at night (thus primarily mammalian predators) or day (primarily avian predators) varied in relation to distance from woodland patches.

Conclusions: High levels of nest and chick predation in wet grassland landscapes limit the capacity for breeding wader populations to be self-sustaining. Consequently, identifying manageable landscape features that influence predation rates is an important focus of conservation research. Lapwing avoid breeding close to woodland but, as nest predation rates do not vary with distance from woodland patches, their removal may increase the area of suitable nesting habitat but is unlikely to substantially influence productivity.