Curiosities about Barcelona's Peregrine Falcons: diet, moulting, displacements and relations with other species

DIET
Since 1999 Barcelona a total of 252 prey have been identified corresponding to 29 different species, demonstrating the wide range of species that make up the Peregrine's diet.

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This said, the most frequently consumed species is the feral pigeon (Columba livia var. domestica) which represents 52% of the prey identified. The song thrush (Turdus philomelos) makes up 10% of the total, all of which are captured in autumn and winter. Monk parakeets (Myiopsitta monachus) make up 5%, collared dove (Streptopelia decaocto) and moorhen (Gallinula chloropus) 4% and starling (Sturnus vulgaris) 3%. The remaining 23 species represent 22% of the total.

MOULTING
All birds replace their old feathers with new ones every year. This process is known as "moulting". Its frequency and the type of feathers (body, tail, wings, etc.) replaced each time vary in each species or groups of species. When all the body's feathers are replaced, this is termed a full moult. If, in contrast, only the body's feathers are replaced - not the flight feathers (wing and tail) - this is termed a partial moult. In both cases, moulting involves a considerable energy expense for the bird, and so usually takes place when temperatures are favourable and resources are abundant. Young and adult Peregrines undergo a full moult every year at the beginning of spring. Research shows that Peregrines only moult once, with no other moult taking place -neither partial nor full. However, some juvenile Peregrines in Barcelona do not follow this general pattern of the species, undergoing in addition to the full spring moult, a partial moult during the autumn of their first year. During this process they replace some of their body feathers. The reason for this variation in the general pattern of the species is not known, but it could be related to the fact that autumn and winter in Barcelona is not as unfavourable as elsewhere, with abundant food available throughout the period and a mild climate.

MOVEMENTS
A male Peregrine released in 2002 on the building of El Corte Ingles in Plaza Catalunya was found injured in the autumn of the same year in the town of Torroella de Montgrí (Baix Empordá). Three years later, once the bird had recovered from its injury, it was released on Montjuïc. A female Peregrine released in the spring of 2002 in the Port of Barcelona was spotted several months later in the Port of Tarragona. A Peregrine released in 1999 in the Palau Nacional de Montjuïc, another released in 2003 in the Church of Sants Just i Pastor and another hatched on the sea cliffs of Montjuïc in 2004 were all found dead, run over on the runways of Barcelona Airport.

RELATIONS WITH OTHER SPECIES
During the hacking work in 1999 in the Church of Santa Maria del Pi, a pair of kestrels (Falco tinnunculus) nesting in the bell tower brought food both to their own chicks and the Peregrine chicks inside the nest box.

Kestrel (Falco tinnunculus)

They almost always brought swifts (Apus apus) and house sparrows (Passer domesticus). When the juvenile Peregrines left the nest box, they lived together with the young kestrels and could often be seen perched together. This phenomenon is somewhat surprising if we consider that both kestrels and Peregrines are highly territorial species which zealously and aggressively protect their offspring. Moreover, Peregrines will occasionally capture and eat kestrels.