Nesting avifauna of Vaasa

The nesting avifauna of the 2005 to 2008 survey was based on the previous survey on incidences of nesting species. The goal was to record the distribution of each species within the city in survey blocks with a size of 1 km². A total of 336 survey blocks were established within the city. Estimations on abundance of specific species were not made. The starting point was to focus on mapping areas of importance to the avifauna and also to determine other green areas vital to biodiversity.

During 2005 to 2008, roughly 30,000 incidences of observed likely nesting by 168 species of birds were recorded in the database. The diversity of species is due to the city’s geographical location near the coast, as well as the diverse natural habitats in the area. Species from both north and south converge in Vaasa. In Finland, there is a total of 230-240 species of nesting birds.

The most common nesting birds in Vaasa are the willow warbler (292), chaffinch (285), hooded crow (280), white wagtail (277) and common gull (273), in brackets the number of blocks in which the species was observed. All of the aforementioned species were found in 85% of the survey blocks combined. The willow warbler and chaffinch are extremely common, nesting nearly everywhere. The second most common species list includes the great tit (258), Eurasian siskin (250), European robin (247), lesser whitethroat (236) and common wood pigeon (229).

Of the southern birds, thrush nightingale (35), icterine warbler (34) and wood warbler (45) regularly nest in Vaasa, albeit large annual fluctuations occur. Of the northern species, the common redpoll appears most often, mostly in deciduous dominated mixed type forests. In northern Finland, on the other hand, there were observations of possible nesting in only four survey blocks.

A newcomer of recent decades, the Eurasian tree sparrow (80), has spread quickly to the Kvarken-region. It was found that this species was just as common as the house sparrow (83). A majority of Eurasian tree sparrows nest in residential areas and the countryside, however an increasing number are finding their way into the heart of the city.

Fifty-nine species of nesting birds were recorded in less than five percent of the survey blocks. Of these, 19 were considered to be sporadic visitors. The remaining 40 species, albeit rare in Vaasa, were regular annual visitors. Among these rarities were the Eurasian tree warbler (12), western capercaillie (10), grasshopper warbler (6), ural owl (5) and spotted crake (2). Sporadic visitors in the area during 2005-2008 were black redstart (2) and woodlark (1). The former was confirmed nesting during 2007 and 2008 and the latter during 2006.

Information on bird species nesting in man-made structures was also collected. A total of 25 species were recorded, the most common being the rock pigeon, common swift, jackdaw and house sparrow. Species noted to be nesting on roofs were Eurasian oystercatcher, arctic tern, common gull and lesser black-backed gull. A black redstart was found to be nesting on a boat docked in the harbor area over the summer. The Eurasian tree sparrow proved to be quite inventive when it came to finding nesting sites. It was observed nesting in locations such as multistory buildings, detached homes, street lamp posts, street sign structures, and supporting structures of electrical transformers.

Table 1. Observed species of birds nesting in buildings and other structures during 2005-2008

Sources

Laine, L., J. 1996. Suomalainen Lintuopas.

Mediakomppania & Lasse J. Laine 1996.

Helsinki.