Honey, I am talking about the Honeycreepers

I couldn’t leave just one post to the Honeycreepers, these birds are fascinating creatures. Endemic to Hawaii they hold much scientific interest as they are an example of adaptive radiation, in other words an example of natural selection (ScienceDaily 2011) (Guardian 2011).

There was once at least 56 species, but only 18 now remain (Guardian 2011). This valuable and delicate species is at a greater threat now due to climate change.

The transmission of pox and malaria in Hawaii depends on climatic conditions, seasonal changes in temperature and rainfall in particular influence the increase or decrease mosquito populations (USGS 2009).

Hawaii provided safe refuges for birds in its more mountainous areas as their usual habitats in the wet forests on lower ground have become malaria . It is thought this area of higher altitude explained why the Honeycreepers were not completely wiped out the first time these non native diseases were introduced (USGS 2009). However the temperature in the mountains is increasing, putting Honeycreepers at a higher risk of contracting pox or malaria. Today, native Hawaiian birds face one of the highest rates of extinction in the world, only three species of Honeycreepers is in decent shape (USGS 2009).The Po‘ouli became extinct in 2004 (Pratt 2009) demonstrating the fragility to their species. 

It is thought if the 2ᵒC increase does happen around 60 to 96 % of the high-elevation disease refuges will vanish (USGS 2009).

The tropical inversion layer which is the thin cloud that surrounds the upper parts of the mountains will soon play a larger role in Honeycreepers survival. With the increase in temperature the layer has become more frequent. The tropical inversion layer affects plant growth so will make habitats further up, away from malaria risk areas, inhospitable for Honeycreepers (USGS 2009).

Deforestation could further alter the patterns of malaria transmission (Sehgal 2009). Deforestation, for example, of the Alaka`I Wilderness Preserve on Kaua`I Island could adjust the pattern of seasonal transmission of avian malaria to a pattern of continuous yearly transmission (Atkinson and LaPointe, 2009).

Natural resistance to avian malaria has developed in one species, the Hawaii amakihi, which is more populous in lower parts of the forest than more elevated areas despite high levels of mosquitoes (Woodworth et al 2005; Kilpatrick et al 2006). It is thought that good habitat management could help other honeycreepers develop some resistance to avian malaria (Kilpatrick 2006). However; warming may be increasing at a rate that will make it impossible for Hawaiian birds to develop a resistance in time. It looks like humans will need to take action or these valuable bird species will be overwhelmed by global warming (Miller 2012). 

Previous posts have focused much more on the effects climate change has on humans, we need to also remember the other creatures that are affected.

Reference

Miller, S. (2012) ‘Climate Change Threatens Hawaiian Forest Birds’, in Keener, V. et al (ed.) Climate Change and Pacific Islands: Indicators and Impacts, PIRCA: Island Press, 11-12