Visitors to Barcelona may not be aware of the Llobregat Delta, a birding haven with over 350 recorded bird species that sits on its doorstep. With thousands of birds passing through each year, it's quite metaphoric that it's annexed to Barcelona airport and not surprising that it's become known as the migrant capital of Catalonia.

With spring migration stretching from February to June and autumn passage from July to November, it seems like the parade of White-winged Tern, Glossy Ibis, Osprey, Garganey, Common Crane and crakes, to name a few, is non-stop. And Llobregat has more than its fair share of vagrants too [Article of interest: why migratory birds from Asia land in Europe].

Also, with the addition of two new sites at Cal Tet and Can Camins to add to the Remolar-Filipines reserve, bird watching tours, short breaks and birding holidays are now even better as the extra habitat has increased the chances of seeing Moustached Warbler, Little and Great Bittern, Collared Pratincole and Penduline Tit amongst others. Read more...

There's so much migrant activity through the year at the Llobregat Delta that bird tours on two consecutive days could easily paint completely different pictures. Which is why we usually squeeze in more than one visit during a bird watching holiday, or even a short birding break.

But even during the rare 'quiet periods' there's always enough herons, waders, shorebirds and passerines in the lagoons, marshes, beaches, rivers and pinedas of the three reserves to justify sneaking a few birding hours off from the stag weekend, business conference or other activity that has brought you to Barcelona.

As the officially designated migrant capital of Catalonia, it's not surprising to hear that the best time to take a bird tour to the Llobregat Delta is during passage times. But the good news is that these times barely stop.

White-winged Tern and Marsh Sandpiper may be the pick of the April-May peak, but Spring actually spans from late February (e.g. crakes) to early June. And before the month is out waders in full summer regalia kick-off the Autumn, via raptors and Dotterel, to the November stopover of Common Crane.

During Autumn passage, an added birding tour to watch raptor migration from the Collserola Park is a must.

The complex eco-system that is the Llobregat Delta continues its resistence to definition with Summer actually providing refuge for non-breeding waders, early waves of Autumn migrants and post-breeding arrivals of Kingfisher ready for their winter stay!

The orthodox Summer attractions include Little Bittern playing hide and seek at Cal Tet, Collared Pratincole and Spoonbill outside the Filipines hide and flocks of waders, Audouin's Gull and Gull-billed Tern on Ca L'Arana beach.

And you always have the option of adding a visit to the Garraf Massif or Collserola as part of your birding day trip.

A bubbling carpet of thousands of ducks, Golden Plover and Lapwing provide a boisterous backdrop to a birding tour to the Llobregat Delta in Winter - and in amongst them a full set of wintering waders as well as Kingfisher, Penduline Tit, Little Bittern, Water Pipit and Bluethroat.

Singing Moustached Warbler blow their cover in the reedbeds whilst Stone-curlew stay cryptic on the local farmland and nearby Gannet and Balearic Shearwater contrast with a vibrant and thrilling oceanic display.

But it's the infamous Great Bittern that really gets the heart racing, and is possibly topped only by 'adding-on' a Garraf Massif bird tour for local Wallcreeper.

4. Rainfall however can have a major say in precisely where vagrant and migrant birds 'fall' so check locally after night storms.

5. Proximity to an existing migration route ensures sites like the Llobregat Delta benefit from relatively minor weather-related errors.

6. A Coastal location like Llobregat Delta will also benefit from falls of oceanic migrants.

1. A querk in genetic programming, making some birds 'buck the trend', is a safety net of natural selection and can be a precursor to colonisation. See Blackcap.

2. Inexperienced younger birds can migrate past their normal breeding/wintering range.

3. Wind conditions can contribute but it seems unlikely that birds being 'blown off course' plays a crucial role in true vagrancy.