Birds breeding in the urban centre of Gliwice (Silesian province) in the years 2016–2017 and the changes of breeding bird communities in Polish town centres at the turn of 20th and 21st century

A breeding bird census was carried out in the town
centre of Gliwice (Silesian province) in the years
2016–2017 on the same plot (15 ha), where it was
originally done in the years 1988–1990. Surveys in
both periods were conducted by the author with the
use of the same methodology. The environment of
the densely developed town centre has not changed
substantially over the 30 years. Lesser Whitethroat
Curruca curruca and Green Finch Chloris chloris
stopped breeding in the area, while some new species
appeared: Magpie Pica pica, Blue Tit Cyanistes
caeruleus, Great Tit Parus major, Blackcap Sylvia
atricapilla, Starling Sturnus vulgaris, Fieldfare Turdus
pilaris and Serin Serinus serinus. The density of
all breeding species decreased by 15%. A marked
decrease of the House Sparrow Passer domesticus
and Collared Dove Streptopelia decaocto and a huge
increase of the Feral Pigeon Columba livia f. urbana
and Wood Pigeon Columba palumbus abundance
were recorded.  The probable annual rate of changes
(accumulated annual index – CAGR) in these species
amounted to: -9% in House Sparrow, -7% in
Collared Dove, +12% in Feral Pigeon and +17% in
Wood Pigeon. A pronounced occurrence of some
parallel changes in the avifaunas of similar town
centres in Poland, albeit with varied geographical
position and climate, has been observed. A remarkable
drop of the Collared Dove abundance in the
densely built-up urban areas is surprising in the
context of its overall countrywide population increase.
It may hint at the occurrence of desynurbization,
so far undescribed for this species, i.e. moving
away from the city centres to the suburban or even
rural areas.