Individual study: Forest restoration has positive effects for some, but not all, native birds in Hawaii
Camp R.J., Pratt T.K., Gorresen P.M., Jeffrey J.J. & Woodworth B.L. (2010) Population trends of forest birds at Hakalau Forest National Wildlife Refuge, Hawai'i. The Condor, 112, 196-212
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Reduce adverse habitat alterations by excluding problematic terrestrial species
A study in two koa Acacia koa forests in northern Hawaii, USA (Camp et al. 2010), found that all seven native birds recorded in an area of open forest from which feral grazers (cows and pigs) had been excluded showed long-term population stability or growth. However, all but two showed short-term declines. In a closed forest from which grazers were excluded, only two species showed an increase, with the rest either stable or declining. Birds were monitored between 1987 and 2007 in the open forest and 1999 and 2007 in the closed forest. This study is also discussed in ‘Habitat restoration and creation – Forest restoration’.
Exclude grazers from semi-natural habitats
A study in northern Hawaii, USA (Camp et al. 2010), found that seven species in an open koa Acacia koa forest from which feral grazers were excluded showed long-term population stability or growth, but only two were increasing in a closed forest with grazers excluded. This study is discussed in ‘Threat: Invasive and other problematic species - Reduce adverse habitat alterations by excluding problematic species’ and ‘Habitat restoration and creation – Forest restoration’.
Restore or create forests
A study in a restored koa Acacia koa forest in northern Hawaii, USA (Camp et al. 2010), found that three native birds showed long term population increases, with populations of the common ‘amakihi Hemignathus virens, the ‘i’iwi Vestiaria coccinea and the apapane Mimatione sanguinea all at least doubling between 1987 and 2007. Densities of ‘amakihi were similar to those in closed forest (lower than in open forest), densities of i'iwi and apapane were much lower than in the forests. Three native, endangered species (‘akiapola’au H. munroi, Hawaii creeper Oreomystis bairdi and Hawaii akepa Loxopus coccineus) were not seen in enough numbers to be analysed. This study also investigates the impact of grazer exclusion and removal from native vegetation, discussed in ‘Threat: Invasive and other problematic species - Reduce adverse habitat alterations by excluding problematic species’.