The latest edition of The Conversation’s Imagine newsletter is a feature on animal migration by Jack Marley, Environment commissioning editor. This is how it begins:
“Throughout Earth’s long history, myriad beings have taken flight when conditions became too harsh – as seeds or spores, or on feet, paws, wings and fins. The same is happening today. Rising temperatures are forcing species to move where the climate still allows them to feed, breed and live healthily. But just as this grand migration is getting underway, rigid barriers (both physical and otherwise) are thwarting life’s efforts to adapt. Animals that migrate long distances during their lives are among Earth’s most threatened according to a new report. Of the 1,189 species tracked by the United Nations Convention on the Conservation of Migratory Species, 44% are declining. So why is migration so dangerous?
A moving target
“Every year, birds weighing about 300 grams leave Siberia and fly non-stop to Australia,” say Richard Fuller, Daniel Dunn and Lily Bentley, biodiversity scientists at the University of Queensland. These birds are bar-tailed godwits and their non-stop flight covers 13,000km – one of the longest known continuous migrations.
“Their journeys are critical for their life cycles – to find food, mates or a better climate. To undertake these journeys, animals must be in good condition with plenty of fat stores, and they must have safe flyways, swimways and pathways.”
When species gather in large numbers to traverse vast distances, they tend to tempt the hunters and fishers they pass. Consider the passenger pigeon, a bird whose flocks once darkened the skies of North America but whose last known member (Martha) died in a zoo in 1914. Migratory species highlight the inadequacy of conservation measures which end at one nation’s borders, the team argue. Only 8% of the world’s protected land is joined up. “Because of this, animals have to make daring sorties across unprotected land or sea to complete their journeys,” they say. Safe resting sites, critical “stepping stones” along the way, are vital for these weary travellers to recover. If just one is lost, the whole chain can collapse. …”
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