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9 - Climate change and conservation of waders
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- By Ilya M. D. Maclean, University of Exeter
- Edited by Brooke Maslo, Rutgers University, New Jersey, Julie L. Lockwood, Rutgers University, New Jersey
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- Book:
- Coastal Conservation
- Published online:
- 05 June 2014
- Print publication:
- 27 March 2014, pp 265-286
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Summary
Introduction
The world’s climate is changing rapidly. In the last 50 years, global temperatures on land have risen by approximately 1°C, and over the next 100 years a further rise in temperatures of at least 2°C is expected (IPCC, 2007). This rise may not seem like much, but the rate of temperature change is unprecedented in recent history, and many animals and plants are struggling to keep pace (Chen et al., 2011). Wading birds (Charadrii) are particularly susceptible to climate change (Maclean & Wilson, 2011). Many species travel over large sections of the globe during the course of their annual cycle and use habitats in many different biomes and climate zones (Piersma & Lindstrom, 2004). The majority of waders breed in the high Arctic, a region warmer now than at any time in the last 125 000 years and undergoing further warming at a rate almost twice that of the global average. Other species breed in freshwater marshes, which are threatened by increased drought. During the winter periods, the majority of waders move to coastal habitats where they experience climate-related threats associated with the marine environment. Global sea level rose ~17 cm during the last century, but the rate in the last decade is nearly double that of the last century (Church & White, 2006). Significant habitat loss and change has occurred as a result, and even greater changes are expected in the future (Chu-Agor et al., 2010). The magnitude of future changes in sea level are very difficult to predict because of uncertainties associated with understanding the extent of polar ice sheet loss. However, the last time polar regions were significantly warmer than at present for an extended period, reductions in polar ice volume led to 4–6 m of sea level rise (IPCC, 2007). Marine invertebrate prey of waders are also susceptible to changes in ocean chemistry. Ocean acidity has increased by ~30% as a result of higher levels of dissolved carbon dioxide, with concomitant deleterious impacts on calcifying organisms (Orr et al., 2005). Moreover, temperature increases and changes in ocean circulation patterns have been linked with reductions in dissolved oxygen in coastal and marine systems, with extremely damaging consequences for the fauna associated with these habitats (Grantham et al., 2004). Many of these species are part of the food web on which waders rely.
Effects of habitat degradation on avian guilds in East African papyrus Cyperus papyrus swamps
- Ilya M. D. Maclean, Mark Hassall, Rosalind Boar, Oliver Nasirwa
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- Journal:
- Bird Conservation International / Volume 13 / Issue 4 / December 2003
- Published online by Cambridge University Press:
- 20 November 2003, pp. 283-297
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- Article
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The density and species richness of bird communities in disturbed and undisturbed stands of papyrus Cyperus papyrus were compared. Point counts, corrected for different probabilities of detection in different swamps, suggested that the species richness of bird communities in stands of papyrus disturbed by burning, grazing or pollution was higher than in nearby stands that were not disturbed. However, there were fewer species and individuals of highly specialized birds or species characteristic of papyrus, in disturbed stands than in undisturbed swamps. At < 1 ha-1, the density of Papyrus Gonolek Laniarius mufumbiri in Ugandan swamps was, for example, significantly lower in polluted and burnt sites than in undisturbed papyrus where up to 13 ha-1 were recorded in the centre of swamps. White-winged Swamp Warbler Bradypterus carpalis was only recorded in undisturbed papyrus. In the papyrus that fringes Lake Naivasha in Kenya, outside the geographical range of species restricted to papyrus, disturbance in the form of grazing selects against species classified as swamp-reliant. Species classified as generalist users of papyrus were much less sensitive to disturbance than specialists. The density of swamp specialists was also lower near the edge of swamps, where total species richness was higher. These results are discussed in relation to conservation management of papyrus swamps in East Africa.