The macroecological distribution of avian functional diversity: environment, extinction risk and protected area coverage

134 bird species have gone extinct since 1500 and more than a fifth are currently threatened or near-threatened. Consequences of biodiversity loss for ecosystems depend on community composition rather than simply species richness, hence interest in functional diversity (FD) - variety of traits that influence ecosystem functioning – has increased. This thesis uses a global set of avian traits and geographic range maps to investigate the macroecological distribution of FD. Old World latitudinal gradients of FD are found to reflect contemporary environment, particularly energy availability. Analyses restricted to sedentary species reveal the importance of migration (e.g. for breeding assemblages a positive association with temperature seasonality explains 6.7% of the variance in FD having accounted for species richness, whereas a negative association explains 21.4% for residents). This is further investigated by comparing seasons across the Palaearctic-Afrotropical flyway, e.g. functional richness (volume of trait space occupied by an assemblage), which ranges from 0 to 0.33, declines by 0.08-0.17 in the northernmost cells in the non-breeding season compared to the breeding season. Some traits increase sensitivity to human disturbance, e.g. habitat breadth, but birds across South and Southeast Asia are used to demonstrate scale-dependence; traits explain 21.4% of the variance in global extinction risk compared to 6.7% for local extinction with diet type more important in the former and use of manmade sites in the latter. Globally, narrow-ranging species are less likely to inhabit protected areas (12% of land surface) and analyses show they are associated with particular regions of trait space (those related to higher habitat strata, feeding at lower trophic levels and smaller body size) compared to better protected, wide-ranging species. By identifying the main environmental correlates of FD, factors associated with extinction risk and current FD protection, these findings could help identify areas at future risk of decreasing delivery of ecosystem processes.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2014

Author dc:creator

• Romans, Amy

Language dc:language

en