Summary 1.We examined the influence of local weather conditions on reproductive success, timing of breeding and survival in a population of a multi-brooded ground nesting passerine (woodlark Lullula arborea) over 35 years. 2. Woodlarks laid larger clutches when rainfall was low and temperature high during the egg-laying and pre-laying period. Nest success increased with higher temperatures during the nesting period. In successful nests, the number of chicks fledged per egg laid was greater when weather was drier during the brood stage. 3. Although woodlarks bred earlier in years with warmer early spring temperatures, with the onset of breeding varying by 25 days, there was no significant advance in the onset of breeding over the 35 years of study, due to considerable inter-annual variability, and no overall trend, in weather. 4. Simulation modelling of annual reproductive output demonstrated that earlier breeding could increase productivity by 23AE5% in the warmest compared to the coldest year, due to birds having more nesting attempts. Other effects of weather on productivity affected breeding output to a lesser extent. 5. Effects of weather on productivity were minor compared to an increased rate of nest predation through the period of study, which reduced productivity by 49AE8% by 2004 compared to 1971. 6. Turning points analysis identified three distinct demographic periods: from1971 to 1988 the population grew slowly, during 1988-1999 the population grew rapidly, but after 1999 the population declined. Increased population growth after 1988 was associated with higher first-year survival rates (estimated using a population model). Population decline after 1999 was caused by a combination of reduced productivity (resulting from increased nest failure rates attributed to predation) and lower first-year survival rates, that appear unrelated to winter temperature. 7. Climate change (long-term changes in weather) did not explain the marked changes observed in the population trajectory over 35 years. We suggest that understanding effects of both climate and habitat change on populations is essential in predictive population modelling.
Capsule Set-aside schemes have allowed breeding Woodlarks to colonize farmland, but heathland and forestry habitats remain the stronghold. Aims To determine which habitats provide the best conditions for breeding Woodlarks and whether a buffer effect is operating, with density increasing faster in the poorer quality habitat as the population grows. Methods Habitat colonization was examined and breeding success compared among heathland, clearfelled and young conifer plantations, and farmland set-aside. Results Woodlarks on heathland and forestry habitats had similar clutch sizes and nesting success, but clutch sizes may be lower on farmland. Heathland was recolonized when population density was low in forest habitats, while farmland was colonized when density was increasing, and areas close to forest were preferentially occupied. Woodlarks breeding on farmland preferred set-aside stubbles to other field types. Conclusion Forestry and heathland habitats are similar in quality for breeding Woodlarks, with no evidence for a buffer effect. Farmland set-aside may be suboptimal but the area available is much greater than the area of forest or heathland, and could therefore make a significant contribution to the conservation of the Woodlark population. However, set-aside should not be seen as an alternative to the conservation of forest and heathland.
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