Archive for November, 2012

The Plain Tiger (Danaus chrysippus) in Barcelona

 

Written by Lucy Brzoska

I half-glanced at the orange butterfly, expecting to see a Wall (Lasiommata megera), an abundant species on Montjuic. After a double-take, I realised it was something else altogether. Having looked wistfully at so many photographs of this species, recognition was instant. I was moving carefully forward with the camera, when a jogger pounded past, and the Plain Tiger was gone.

But a quick scramble up the slope, behind a bush of broom, revealed large clusters of Coronilla de Fraile (“Friar’s pate” – Globularia alypum), and there, feeding calmly, were three Plain Tigers.

D. chrysippus is an extremely common butterfly species in Africa and Asia, but a recent arrival in Iberia. A strong migrator, after emerging, each generation moves on.  Well-established in Andalucia, they have been recorded all along the Mediterranean coast as far north as Roses on the Costa Brava. JM Sesma of Biodiversidad Virtual suggests the ones I saw were the progeny of Tigers recorded in the Delta del Ebro two months previously.

The Plain Tiger is a cooperative butterfly to photograph.  Rather than erratic flight, or camouflage, it protects itself by toxicity, so readily displays its colours to potential  predators. The Tiger’s wings, with a range of tones – from orange to russet and brown – sharply outlined in black, are beautiful, but best of all, in my opinion, is the body and head, covered in striking white polka dots.  The males are distinguished by a prominent white spot on the  hind underwing, edged in black, which is a concentration of scent scales used for mating.

Interestingly, the spread of D. Chrysippus in Iberia has been abetted by the widespread invasion of a garden escapee, Gomphocarpus fruticosus, a member of the Milkweed family.  Danaid caterpillars feed on Milkweed plants, storing up the toxic alkaloids from their milky sap, enough to make an unwary predator vomit.

 

Migration of Cranes autumn 2012

The autumnal migration of cranes (Grus grus) into Spain usually takes place inland, over the Pyrenees.  On the last weekend of October there was an abrupt change in the weather, with temperatures plummeting and an extremely strong north wind.  On Ornitho.cat, someone in Sant Andreu de la Barca (near Barcelona) recorded hearing cranes passing at 3 in the morning. This was only the beginning. While walking in Collserola on Sunday morning, an unmistakable trumpeting made me look up to see a group of 22 cranes, circling and orienting themselves in a SW direction. The observations on Ornitho.cat came thick and fast during the day. One entry from the Delta del Ebro recorded 1,300, the observer noting the whole sky covered with skeins. The map from Ornitho.cat (yellow= 28th Oct, red = 29th) reflects this remarkable event, when the weather conditions forced the cranes into an intense coastal passage, well to the east of their usual route, much to the delight of ground witnesses.