M. Ausden’s scientific contributions

Since the middle of the twentieth century, the conservation of bird habitats has developed enormously, in response to increasing habitat loss and deterioration.The approaches to conservation have been varied, including national and international designations, nature reserves, agri-environment schemes and large-scale habitat creation. In this paper, we outline the history, successes, limitations and challenges of habitat conservation. Important recent trends have been: increasingly refined approaches to habitat management on reserves and other protected areas; a growing emphasis on conservation in the wider countryside (i.e. outside reserves); and the emergence of large-scale habitat creation initiatives. Protection and management of habitats on reserves, especially for scarce species, has been broadly successful but it has proved far more difficult to reverse major declines in the populations of many farmland, woodland and upland bird species in the wider countryside. Climate change and the potential for further intensification of farming represent two major challenges ahead. Future approaches to habitat conservation will need to embrace several lines of thinking, including enhancing habitat complexity at different scales; taking more of a landscape-scale outlook to conservation efforts; exploring the potential of 'ecosystem service' approaches; and, especially for wetlands, the creation of extensive new habitats.

We identify 18 trends in habitat quantity or quality considered to be important drivers of change in bird populations in the twentieth century. The trends are grouped into changes in (i) farmland (including the uplands), (ii) wood land/forestry, (iii) coastal and inland wetlands and (iv) miscellaneous (urbanisation and recreation). Shifts in habitat quality were just as significant to birds as changes in habitat extent. Many of the trends had complex effects on birds, benefiting some species but creating pressures for others. Overall, habitat changes in lowland and upland farmed landscapes have been detrimental to birds. Expansion of conifer plantations had mixed effects, replacing long-established bird communities with new ones.The decline in coppicing and recent changes in lowland woodland structure caused several species to lose habitat but few have gained.Two striking changes affecting wetland birds have been the modernisation of sewage treatment systems and the increase in man-made waterbodies. Eight habitat-related issues are identified that are likely to be especially significant to birds in the first half of the twenty-first century.