By the riverside

River Guadiana (Martin Kelsey)

Spring ended with a thump. Suddenly we are where we should be in middle of June: summer, with cloudless skies and crispy dry blonded vegetation. Yet, just over a week ago this extraordinary stretched-out spring gifted us moderate temperatures, clouds and meadows still looking like an artist's palette, chaotic in colour. A whole cycle has spun slower this year. Plants have flowered later (our olives are still in blossom), fruits are several weeks later than normal. But the cool and damp spring held butterflies at bay.

I spent most of the day walking along the banks of the Guadiana River, the second great watercourse through Extremadura. It moves sluggishly east to west across the northern half of the Badajoz province. Helped by temperatures close to 40ºC, it had a truly tropical feel about it. It reminded me rather of the Nile in southern Sudan. There is a gallery woodland of poplars, ash and willows, with stretches of exotic eucalyptus as well. Giant reeds stand bamboo-like and, to exemplify the tropical touch further, patches of the invasive water hyacinth give a lurid glossy green carpet to stretches along the river.

The dragonflies were fewer than I had hoped for, testament again I believe to the slow spring. But the most common species was the Violet Dropwing, obelisking in the heat from favourite perches overhanging the water. Unlike the exotics such as the water hyacinth and eucalyptus, this species whilst hailing from Africa, has arrived onto the Iberian peninsula under its own efforts. First recorded in Spain in 1979, it is now widespread in Extremadura. 18% of the Odonata fauna here is of tropical African origin, indicators it would seem of climate change.

Violet Dropwing (Martin Kelsey)

As I explored the bankside vegetation, despite the high temperatures and it being already midday, I was surprised by the amount of bird song. Species present in these wetter habitats tend to continue singing longer into the season and later in the day. Had I been walking in evergreen oak dehesa at that moment, I would have heard very little sign of birdlife. But here beside the river, there was the conversational chat of Reed Warblers, the harsh raucous notes of Great Reed Warblers and the syrup-like flow of sound from Golden Orioles. Quickly I also found Nightingales, Cetti's Warblers and Blackcaps.

In a clump of willows, another song contributed to this audio gallery. Whilst carrying some Reed Warbler-like notes, it also rang with repeated "tchec..tchec..tchec" sounds, especially at the start of each phrase, which developed an exuberance that a Reed Warbler could never match. For a while, the bird remained hidden, but eventually rather clumsily came into partial view through the twigs and foliage. Clearly bigger that a Reed Warbler, with colder brown upperparts, what immediately drew my attention was a large, broad-based orange bill. It was a Western Olivaceous Warbler.

I spent the next quarter of an hour watching it, or rather trying to do so, since it was determined to stay hidden in the willows. At last it gave a short, heavy song-flight across my path and settled to sing on the bare dead twigs on a eucalyptus bough.

Western Olivaceous Warbler (Martin Kelsey)

It was only ten years ago that breeding was first confirmed of Western Olivaceous Warblers in Extremadura. Indeed there were only five sight records between 1995 and 2007. But since then local birders have much better understood both its habitat (typically riverine willows and scrub), its identification and phenology (the first ones arrive in late April, but most do so in May). This year so far, it has been recorded from 22 different locations, mostly along the Guadiana River, but also from three sites in north-west Extremadura. My record was at a previously unknown site, but I have also seen it this year at known localities. Suitable habitat is present along much of the course of the Guadiana and I would be surprised if the true population was not much larger than currently known. What we do not know is whether this significant change in status is merely an artefact, based on better knowledge and more effort being made to locate the species, or whether it, like the Violet Dropwing, is also an indicator of climate change.