Common swift / Mauersegler (Apus apus)

Mauersegler, Sils-Maria. 2020-06-10 12.30.10 Sils
Classification: Genus Apus; Subfamily Apodinae; Family Swifts (Apodidae)
Vielleicht haben wir bald Mauersegler Brutkaesten am Haus!
Vocalization: A shrilling trill "zreeeee" of about 1 -2 seconds length, gradually rising in pitch with accentuated firs half, then falling from the middle of phrase. [Link]
Calls: Often continued with a dry lower pitched "trrrrrr" before calling again. Very vocal at breeding area, and often a flock will call together. Despite being quite similar to Pallid Swift, the call is probably the best field character to separate the two. Pallid puts the stress on the ending of the call, followed by a quick fall in pitch (dynamics like moaning with a quick release). Plain Swift calls similar to Common Swift, but differs in slightly fluctuating pitch during the call, and a loss of resonance towards the ending (thinner sounding). [Link]
Physical details: length=16-17 cm, wingspan=42-48 cm, weight=31-56 g
Habitats: Settlement

First documented observation : 2020-06-10 in Sils.