Iberianature

Invasive species in Mallorca

Balearics, invasive species | Tags: biodiversity of Mallorca, Coatis in Mallorca, Environmental issues in Mallorca, Exotic pets in Spain, Mallorca, Sierra de la Tramontana|

Tiger mosquito reaches Girona

The tiger mosquito continues its slow and seemingly unstoppable march, and has now reached Roses and L’Escala in Girona according to the Servicio de Control de Mosquitos de la Bahía de Roses y el del Baix Ter. La Vanguardia

Catalonia, Invertebrates, On Spain, invasive species | Tags: Girona, tiger mosquito|

Tiger mosquito continues to expand

The tiger mosquito continues to expand in Catalonia, doubling its area of distribution between 2006 and 2007, and now present in 55 municipalities including Barcelona. El Periodico

See also arrival of tiger mosquito to Spain (2005)

Barcelona, Catalonia, Invertebrates, On Spain, invasive species | Tags: tiger mosquito|

Beaver erradication begins

La Rioja, Mammals, On Spain, Spanish rodents, invasive species | Tags: beavers in Spain, River Ebro|

Beavers in Spain – Castores en España 2

Following on from the Beavers in Spain news, European beaver expert Dr Duncan Halley of the Norsk Institutt for Naturforskning has very kindly written this facinating piece for Iberianature on the Navarran beavers.

“The reasoning of the Spanish authorities, that allowing illegal reintroductions to take place sets a bad precedent, is quite understandable. Conservationists often complain when others take the law into their own hands, e.g. by illegal shooting of protected species; the same principle applies here.

In 2005 I was contacted by scientists working for the Navarrese regional government, who sent some pictures of unmistakable beaver signs they had come across while working on European mink. I later visited the site, and saw from a video that the animals are definitely breeding. The exact site I saw was the most favourable for beavers I think I have ever seen, oxbows off a main river with thick, shrubby growth of poplars (easily the beaver’s favourite tree genus), and lots of herbaceous growth as well. Combined with the very benign climate and the very large amount of suitable habitat available on the Ebro system, I have no doubt the species, left to itself, will become firmly established. Unmanaged the river system could support a large population, probably over a thousand individuals. After at least four breeding seasons, the population, allowing for natural increase, is probably well in excess of 50.

As regards the technical aspects of a removal effort, it’s worth recalling how extinction occurred. Beavers were hugely reduced in numbers in most places by mediaeval times, but in most of Europe, including Spain, small populations hung on for well over 500 years until the 17th-19th centuries, the 17th century seeing the arrival of accurate firearms and efficient steel traps. These last beavers tended to be in the best beaver habitat, marshes or large rivers with plenty of cover and no need to dam, or even fell trees much; beavers were therefore hard to find there. The conditions for final extinction also included the very high value of beaver fur combined with the value of the castoreum gland (medicine, perfume), literally worth more than its weight in gold. One beaver was worth more than a Norwegian farmhand’s annual wage in the 18th century, to give perspective. Every man’s hand was turned against them, and by the C17th most people could get hold of a gun or a trap if a beaver was noticed.

Under modern conditions, to remove beavers from a watershed as large as the Ebro requires a professional effort, as the animals no longer have significant commercial value (except for sport hunting in some places). In the case of the Ebro, there are two factors further complicating a removal effort. At low populations beavers typically select strongly the very best habitat patches, living in burrows and felling few trees; in areas with much bushy growth by the waterside, nothing larger than twigs. This will make finding all the sites difficult in a big river system with so much suitable habitat. Interpretation of signs can also be problematic: are they caused by an established family or just a passer by? All this takes time, and so money. Secondly, at least four breeding seasons have occurred since reintroduction. At low population densities, beavers disperse as yearlings and very much evidence shows they will travel long distances – many cases of over 50km are known – to find the very best habitat rather than settle close to their natal territory.

It seems the trapping will be carried out in La Rioja and Navarra only; however, the Ebro runs into Aragon just downstream from the known reintroduction area, the north bank is in the Basque Country not far above it, and the river runs on into Castile y Leon another 20km or so upstream. All these are well within the recorded dispersal distance of beavers in unsaturated habitats, and it is highly probable that some beavers are established there by now. A trapping effort confined to Navarra and La Rioja with therefore probably leave breeding groups both up- and downstream, from which young animals can redisperse into those provinces.

It appears that live trapping will be the preferred method. There are two effective methods, dazzle netting using a trained trapping crew operating at night, effective but expensive given the manpower requirements; or Hancock traps, which are set partly in the water on the riverbank, and baited with territorial scent or poplar twigs. When triggered, they scoop the animal up from below so that it ends up sitting in a basket above water level.

To summarise, an effective removal is technically feasible. However, it will have to carefully check many tens of km of riverbank for beaver signs, a considerable way up and downstream from the known reintroduction area, including stretches beyond Navarra and La Rioja, determine where the settled groups are, and trap them all. The Ebro is a particularly difficult river system for the purpose, being so large and containing so much good habitat; the resources put into the effort would have to be commensurate with this. If the effort is confined to Navarra and La Rioja, the prospects of complete success depend on whether beavers are established elsewhere on the river. Given their known behaviour and the local political geography, this must be regarded as highly probable.”

By Dr Duncan Halley, Norsk Institutt for Naturforskning

La Rioja, Mammals, Navarra, invasive species | Tags: beaver history, beaver introduction, beavers in Spain, River Aragon, River Cidacos, Strabo|

Alligator caught in River Besòs

A young alligator (70 cm) was caught in Barcelona in the River Besòs yesterday. The reptile was spotted by a local naturalist doing a study on birds. Experts believe the mild temperatures on the Catalan coast and the abundant presence of swamp crayfish may allow alligators to survive the winter here.  This is the second alligator to be caught in just over a year near Barcelona, after the larger alligator caught in a pool in Collserola. (El Pais)

Barcelona, Catalonia, invasive species, reptiles & amphibians | |

Barcelona’s parakeets to be culled

I received this email this morning. It’s based on this article http://www.20minutos.es/noticia/260758/0/autorizan/caza/cotorras/ . Although I have grown to love this pesky fellows I myself have no intention of signing this petition as potentially monk parakeets could cause big problems in the surrounding countryside to farming and wildlife. I hope they are only going to reduce numbers. If you don’t agree with me, please sign their petition. More on monks here: http://www.iberianature.com/material/barcelona_birds.html

“Dear Mr Lloyd,
A contact e-mailed me yesterday about the planned wild parrot hunt in Barcelona. I am based in Brooklyn and the monk parakeets live here peacefully with other wildlife. I am shocked and discouraged by this planned action and am organizing a protest. But there is not much I can do on this side of the Atlantic. What’s needed are voices in Spain that are against it.I have written about this issue and have an online petition. If you could spread the word in Europe, I’d be grateful”
Full story here:

Barcelona, birds, invasive species | |

Black flies in the Ebro

My Tortosí friends have been complaining about these for several years now. The images of the bites I’ve seen on TV are nasty. We’re actually dealing with two species from Africa Simulium intermedium and Simulium ornatum On occasions, farmers with orchards along the River Ebro have had great difficulty harvesting their crops

Black flies in Catalonia

http://en.wikipedia.org/wiki/Black_fly

Spain hit by plague of blood-sucking black flies

Dale Fuchs in Madrid Monday June 25, 2007 The Guardian

A plague of black flies has prompted authorities in north-eastern Spain to issue warnings on TV and fliers advising people to cover up and avoid riverside areas in the early morning and dusk.
The insect has been quickly breeding – and sucking blood – along the rivers and reservoirs of Catalonia and Aragon, causing alarm in small towns.

Only two to three millimetres long, the fly is much smaller and harder to spot than most mosquitoes, but its voracious bite sent more than 2,000 people to hospital last year in Catalonia alone. Its vigorous jaw, which releases a cocktail of chemicals, can produce allergic reactions.

“If the mosquito is a neurosurgeon that bites with a probe, the black fly is a butcher that scratches the skin and makes you bleed,” Raul Escosa, member of an Ebro river environmental board, told El Pais.
“We had to take my 18-year-old daughter to the dermatologist and the allergist because she had a dozen swellings of eight to 10 centimetres,” said Jesus Llop, a town council member in the town of Mequinenza.

The black fly, an umbrella term for several Simulium species, was first detected in the region in 1997, and it has been making its annoying presence increasingly felt. Unlike the mosquito, it breeds in clean river water. Regional experts believe the current outbreak stems from improvements in water quality and new irrigation channels, which created a new habitat.

The insect injects an anaesthetic, an anti-clotting agent and a vasodilator into the skin of its host, who belatedly notices the damage after the fly has moved on. In Switzerland an attacking swarm reportedly killed a calf.

Catalonia, Dangerous animals, Iberian rivers, Invertebrates, invasive species | |