Gulls and Doves

While the migration has been keeping us busy, local birds have been getting on with the business of breeding. Two species have benefited from their association with humans and our habitats and they would not have featured prominently, or at all, in the bird lists of the 19th Century naturalists who explored these parts. The Yellow-legged Gull is hardly mentioned yet today a massive colony breeds on the Rock of Gibraltar, their numbers having built up since the 1970s.

These birds are now sitting on eggs, three being the usual clutch size. We will monitor their progress through the spring.

These birds are now highly aggresive and do not tolerate an approach to the nest. They will get even more aggressive once the young hatch.

The other bird certainly did not feature at all in the 19th Century accounts. The Collared Dove (above) established itself in south-east Europe around 1900. They gradually spread west across Europe and the first pair bred in Britain, in Norfolk, in 1955. They spread south into Iberia somewhat later and spread rapidly in the 1990s. The European population has been estimated at 7 million breeding pairs! It should not be confused with its close relative the Turtle Dove (below) which is a summer visitor, wintering in sub-Saharan Africa that occupies open countryside and rarely ventures into towns.

Collared Doves are ahead of the gulls! The first fledged youngsters are now flying about the gardens in the town, like these by the Gibraltar Museum this morning

adult for comparison

Migrants and their food sources

Female Whinchat

The last few days have seen an almost static low pressure to the west of Gibraltar, over the Atlantic. It has brought intermittent rain, sometimes heavy, and an air stream from the south. It has facilitated the migration of small trans-Saharan migrants giving them a backwind. But the cloud and rain has then forced some birds down. The numbers have not been massive but it has brought down new species for the spring, like the Whinchat (above), Orphean Warbler, Ortolan Bunting and a few others. Some of the birds that had been fattening here left us, including the male Common Redstart that I featured in earlier posts. Other redstarts took its place (below):

The beautiful Melodious Warbler also arrived this week (above and below)

As these photographs illustrate, the Giant Tangier Fennel seems to have been a favourite source of food for these migrants. We have seen how they attracted Subalpine Warblers, Willow Warblers and the resident Sardinian Warblers in earlier posts (21st March, 24th March, 6th April). It seems to be an especially important food source for Willow Warblers, now reaching their peak numbers on migration. The fennel not only provides an attraction to insects, which the warblers eat, but they also provide nectar which the warblers drink as the photographs below illustrate:

The other main food source seems to be the wild olive, now in flower and attracting many insects. It is a favourite among the Sylvia warblers but the Willow and Melodious Warblers like it too:

Whitethroat on olive

Subalpine Warbler on olive

All this commotion is watched attentively by migrant Woodchat Shrikes

Predators of the Mediterranean forest

Short-toed Eagle (archive photograph - 8th March)

We might be forgiven for thinking of the above image as representative of the hunters of the Mediterranean forest. But scale down in size and a whole new world of active and dangerous predators opens up in front of our eyes

They may be beautiful but they are nonetheless formidable hunters of insects, other invertebrates and small vertebrates. The Common Redstart uses a series of tactics depending on conditions

sit-and wait, ready to pounce on prey on the ground is a favourite strategy, not just of the Common Redstart but also of the larger Woodchat Shrike

Woodchat Shrike (archive photo - 24th March)

But Common Redstarts will also hunt from the ground, in lush vegetation or in the open, running at their prey like mini-predatory dinosaurs

When it warms up they will look up instead of down and sally into the airspace to ctach insects in flight. But the birds that use this tactic most now are the small and agile Willow Warblers

Leaping onto unsuspecting prey from the side or above is another tactic used by these predators

Patient stalking is always an option but it is the Sylvia warblers that are best at stalking from within cover, often (as with this Sardinian Warbler) getting the plumage stained by crashing through dense undergrowth into spittle bugs and other sticky characters!

Wherever you look, life is not safe from predators in the Mediterranean forest in the spring!

Gibraltar - a Migration Stopover

The last week has been dominated by strong easterly winds and cloud. These winds kept many migrants within Gibraltar and these birds spent the grounded time feeding and regaining fat and weight that would allow them to complete the migration. A good number of the birds that I reported in the last post were still about yesterday, often within the same patch of ground. These could hardly be described as territories as there was little active defence of them but they are probably best described as temporary homes. Once a good feeding area is established it pays the migrant to stay there, learning the lie of the land, knowing where to fly to to avoid predators and where to best find food. The male Common Redstart in the last post was still around, looking beautiful and in good condition (below):

Nightingales (above, below and post header) are also showing well and some are in regular sites too suggesting that they are also refuelling at the stop over.

Some Chiffchaffs (above and below) are also staying on and, though not easy to separate on plumage, some are seemingly Iberian Chiffchaffs, their calls giving them away 

But new birds have been trickling in, especially as the wind dropped and we got some light rain yesterday:

Tree Pipits (above and below), trans-Saharan migrants heading for north-western Europe, are now moving through

Many migrants, like these Willow Warblers (above and below), make the most of temporary rain pools to wash and groom their feathers, after they have eaten well

...or this female Subalpine Warbler

...and all this activity at a stop over continues while resident breeding birds, like this male Sardinian Warbler, continue their activities among strange and transient neighbours