Targeting conservation efforts to safeguard biodiversity, rather than focusing on charismatic species, could make current spending on threatened birds four times more effective, a new study has shown.

The research, by Imperial College London and the Zoological Society of London (ZSL), is the first to link the costs of protecting threatened species with their genetic distinctiveness, measured in millions of years of evolution. It identifies the top 20 birds for safeguarding maximum biodiversity with minimum spend, of which number one on the list - Botha's Lark - currently receives no conservation spending at all.

The researchers focused on some 200 birds categorised in the International Union for the Conservation of Nature (IUCN)'s Red List as either Vulnerable, Endangered or Critically Endangered, in a study published January 5 in Philosophical Transactions of the Royal Society B.

They found that if conservation spending on these birds continues along current lines, only 85.9 million years of evolutionary history will be safeguarded, compared to a potential impact of 340 million years.

Dr James Rosindell, from the Department of Life Sciences at Imperial College London, explains: "We found that, spent wisely, Pounds 1 can preserve 26 years of bird evolution whilst in the worst-case scenario, it costs Pounds 2485 to save just a single year. So for the cost of a cup of coffee you could probably save a branch of evolution as long as your entire life. However, if you choose to spend your money poorly, you might only save a few hours' worth, not much longer than the time it took you to drink the coffee."

By adapting an approach already in use by ZSL, the researchers categorised the birds in terms of their risk of extinction and their evolutionary distinctiveness, looking not only at how far they had diverged from other species, but also the relative extinction risk of their relatives.

For each species they then calculated the number of years of evolutionary history that could be safeguarded for 50 years by conservation action on that species. Finally, they combined these results with the estimated cost of reducing each species' extinction risk by at least one Red List category within ten years.

The results gave the team a list of the top 20 birds on which conservation efforts should be targeted to maximise the impact of the spend in safeguarding evolutionary biodiversity.

Top of the list was the little known Botha's Lark, a small brown bird that is only found in a restricted part of South Africa and on which no conservation efforts are made at all. Although not the most genetically diverse of the 200 birds, it gains top place because it would require little investment to protect it, making it a very cost-effective species to target.

The tooth-billed pigeon - a large pigeon with a hooked bill, found only in Samoa - gains second place because it is both evolutionarily distinct and the costs required to protect it are relatively low, although still three times the current spend.

Dr Samuel Turvey of ZSL stresses that this isn't about stopping work on more high profile species, but about highlighting the benefits of better allocation of resources: "Our study looked at overall global spending for each species, and of course, the situation on the ground is much more complex, with conversation targets chosen for many different reasons. However, if we do believe that preserving biodiversity should be part of our conservation goals, then our study shows that current spending is fundamentally at odds with what we want to achieve."

Laura Nunes, who worked on the research for her Masters in the Department of Life Sciences at Imperial, agrees: "By combining data from different sources, we've been able to link those birds which are theoretically most important in conservation terms with the real world costs of protecting them. The fact that this highlighted such major discrepancies does pose serious questions about how we choose to target our limited conservation resources to maximise their benefit."

Dr Rosindell adds: "We have to acknowledge that we will never have enough resources to protect all species under threat, so tough choices will have to be made: the 'Noah's Ark' dilemma. However, an encouraging message from our research is that, correctly targeted, we can still do a lot with a relatively small amount of money."

The top twenty birds identified the study were:

Botha's Lark

Tooth-billed Pigeon

Polynesian Ground-dove

Tuamotu Kingfisher

Christmas Island Frigate bird

Chatham Islands Shag

Buff-breasted Button Quail

Giant Ibis

Sangihe Shrike-thrush

Forest Owlet

Raso Lark

Blue-crowned Laughingthrush

Santa Marta Parakeet

White-collared Kite

Marquesan Kingfisher

Sociable Lapwing

Purple-backed Sunbeam

Madagascar Serpent Eagle

Liben Lark

Thick-billed Parrot