Strutting like Mick Jagger: Blue cranes

The blue cranes nonchalantly strutted across the Overberg's wheat fields, about twenty metres from me. They seemed to be seeking attention with their occasional bugling which sounded like a flamboyant version of a goose’s honk. As they strutted, long “tail” feathers, actually part of their tucked up wings, caught the wind providing a distinctly glamorous show. They're certainly charismatic enough to be South Africa’s national bird. If only they'd kept their lanky silhouettes still long enough for a decent photo. I spent yesterday with the cranes in the Overberg's wheat fields as their story highlights some of the issues I’ll be looking at over the next few months. I also want to use the cranes as an example linking the birds to a question I've been asked several times in the last month.

A blue crane surveys the crops

The Overberg blue cranes

Kerryn Morrison, manager of the Endangered Wildlife Trust's African Crane Conservation Programme, explained the significance of the Overberg population to me:

"Over half the entire global population, of around just 25,000 blue cranes, are resident in the Overberg, an area which historically they didn't naturally inhabit". 

Blue cranes are grassland birds and only began extending their range into the Overberg, in the south west of South Africa, when the area's natural vegetation started to be replaced with a patchwork of agricultural grasslands in the 1800s. Subsequently, when cereal / fallow crop rotation was substituted with cereal / pasture rotation, the Overberg's blue crane population blossomed. Much of their natural habitat has been lost to mining, afforestation, housing and other human developments. There would be no blue cranes in the Overberg if we'd not replaced the indigenous vegetation with cereal crops. Around 60% of blue cranes live in these unnatural cereal fields, rather than any remaining natural grassland habitat. It's an example of the huge and sometimes unintentional effects human actions bring about.

Threats

The Overberg's land use change has aided blue crane numbers (albeit at the expense of the species living in the previously existing natural vegetation) but that's not to say the unnatural cereal croplands forming the bulk of the cranes' current territory are secure. If farmers replace wheat with less crane-friendly crops, populations are likely to fall. In the Swartland, to the north west of the Overberg, a recent increase in vineyards coincided with a decline in blue crane numbers in the region.  Changing from cereal crops to olives, fruit or vineyards would all harm crane numbers.

Crossing the Breede River in search of cranes on South Africa's last hand-operated pont

Kerryn told me that the Overberg's farmers are, generally speaking, helpful in adapting farming practices to help the cranes (such as placing stepping stones in water trays to ensure chicks can't drown). However, farmers need to make a profit and might choose to farm other crops. Alternatively the choice might be made for them. BirdLife International and Durham University have completed an analysis of the impact of climate change including a simulated distribution map for blue crane based on current climate change projections. Their research shows that by 2085 around half the crane's existing habitat will no longer be suitable for existing uses. The predictions for the Overberg's Mediterranean style climate are for increased temperatures, an altered rainfall season and less average annual rainfall which, leaving aside the many other implications, would affect the crops which can be grown. 

Climate change almost inevitably moves the topic on to renewable energy. The impact of wind turbines on cranes is not yet known but the development of wind turbines in the Overberg is under discussion. Even if turbines had little effect on the cranes, the turbines would bring more power lines and power lines are estimated to cause around 12% of blue crane deaths. When a new blue crane roost was located at a salt pan near Witsand, Eskom (the national electricity utility) were quick to mark the power lines around the roost. Not all power lines are marked though and yesterday I saw a dead blue crane in a field adjacent to an unmarked cable 1 km south of the salt pan. I couldn't be certain if the cause of death was the cable, but it’s likely.

Impacts down to population growth,  consumption growth or both?

Since starting my research on Too Much Too Many I've lost count of the number of times I've been asked "shouldn't we concentrate on growing consumption in rich countries not population growth in poor countries?" To which I always say “no”. We really ought to be capable of contemplating two related issues simultaneously (and in all countries for that matter). It goes further than that though. 

Much of the blue cranes' natural habitat has been destroyed due to international and domestic demand for minerals and forestry and a domestic demand for housing and other developments. The current unnatural habitat has been developed due to increased international and domestic demand for cereals. One of the future problems looks likely to be additional power cables. A higher human population will use more electricity but we must also hope electricity consumption does increase in South Africa. The 2011 census states 15% of South African homes depend on sources other than electricity for their lighting, such as paraffin and candle light. Paraffin use frequently results in fires with tragic consequences for those living in overcrowded informal settlements. Increasing consumption for, at the very least, those 15% of homes is actually a national priority. Using examples, such as the cranes, highlights how artificial it is to look at the impacts of "consumption" or "population" rather than looking at them combined.

David Attenborough has said "All environmental problems become harder - and ultimately impossible - to solve with ever more people" and I’d add to the end of his quotation "consuming more."  When the causes of issues are so closely intertwined it means any attempt to seek solutions must consider both. This is the reason why, in Too Much Too Many, I'm looking at both the impacts of consumption growth and population growth on blue cranes, many other species, human communities and much else besides.

Look behind you! Farming in the Overberg

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