Search results for "lintukannat"
showing 7 items of 7 documents
The Ghost of the Hawk: Top Predator Shaping Bird Communities in Space and Time
2021
Despite the wide recognition that strongly interacting species can influence distributions of other species, species interactions are often disregarded when assessing or projecting biodiversity distributions. In particular, it remains largely uncharted the extent to which the disappearance of a keystone species cast repercussions in the species composition of future communities. We tested whether an avian top predator can exert both positive and negative effects on spatial distribution of other species, and if these effects persist even after the predator disappeared. We acquired bird count data at different distances from occupied and non-occupied nests of Northern goshawks Accipiter genti…
Mechanisms of population declines in boreal forest grouse
2007
Gilbert Ludwig tutki väitöskirjassaan, miksi kanalinnut ovat vähentyneet talousmetsissä. Suomen metsäkanalintukannat ovat vähentyneet merkittävästi viimeisen 40 vuoden ajan. Pesiin ja poikasiin kohdistuvaa saalistusta on pidetty tärkeimpänä syynä kanalintukantojen laskuun. Hakkuiden ja nuorten metsien osuuden lisääntymisen on katsottu lisänneen myyräkantoja ja niitä syöviä petoja, kuten kettuja, lisäten näin myös kanalintujen pesiin ja poikasiin kohdistuvaa saalistusta. Vuosikymmenten aikana laskenut poikastuotto on keskeisessä roolissa kanalintukantojen laskussa. - Ainakaan teerellä vuotuinen aikuiskuolleisuus ei ole lainkaan lisääntynyt. Hengissäsäilyminen on päinvastoin jopa parantunut, …
Biotic homogenisation in bird communities leads to large‐scale changes in species associations
2021
The impact of global change on biodiversity is commonly assessed in terms of changes in species distributions, community richness and community composition. Whether and how much associations between species are also changing is much less documented. In this study, we quantify changes in large-scale patterns of species associations in bird communities in relation to changes in species composition. We use network approaches to build three community-aggregated indices reflecting complementary aspects of species association networks. We characterise the spatio–temporal dynamics of these indices using a large-scale and high-resolution dataset of bird co-abundances of 109 species monitored for 17…
Effects of habitat restoration on peatland bird communities
2020
Restoration of damaged ecosystems has become an important tool to slow down the biodiversity loss and to maintain ecosystem services. Peatland bird populations have shown a substantial decline during the recent decades in Northern Europe as a consequence of peatland drainage. We studied whether restoration of peatlands drained for forestry affects bird communities. We conducted bird surveys at 11 peatlands in Western Finland, where each of the restored and their pristine counterparts were surveyed before restoration and yearly after restoration during 2010–2018. We used linear mixed effect models to analyze whether restoration affected the number of species and territories of peatland speci…
Titmice are a better indicator of bird density in Northern European than in Western European forests
2022
Publisher Copyright: © 2022 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Population sizes of many birds are declining alarmingly and methods for estimating fluctuations in species’ abundances at a large spatial scale are needed. The possibility to derive indicators from the tendency of specific species to co-occur with others has been overlooked. Here, we tested whether the abundance of resident titmice can act as a general ecological indicator of forest bird density in European forests. Titmice species are easily identifiable and have a wide distribution, which makes them potentially useful ecological indicators. Migratory birds often use information on the densit…
Biogeochemical cycling and ecological thresholds in a High Arctic lake (Svalbard)
2019
Lakes are a dominant feature of the Arctic landscape and a focal point of regional and global biogeochemical cycling. We collected a sediment core from a High Arctic Lake in southwestern Svalbard for multiproxy paleolimnological analysis. The aim was to find linkages between the terrestrial and aquatic environments in the context of climate change to understand centennial-long Arctic biogeochemical cycling and environmental dynamics. Two significant thresholds in elemental cycling were found based on sediment physical and biogeochemical proxies that were associated with the end of the cold Little Ice Age and the recent warming. We found major shifts in diatom, chironomid and cladoceran comm…
Invasive catfish in northern Italy and their impacts on waterbirds
2022
Predatory fish have occasionally been observed preying on birds, sometimes repeatedly, but few studies were able to unravel the overall significance of avian prey in fish diet and the predation impacts on bird populations. We used a control/impact study setup, using a Nature Reserve in northern Italy and a nearby control area, to determine: 1) the contribution of waterbirds to wels catfish diet in the Reserve, 2) the population density of wels catfish in the Reserve and control area and 3) the potential impacts of waterbird depredation by wels catfish on waterbird population trends. Our stable isotope Bayesian mixing model indicated that birds contributed 12.2% (5–27.9%, 50% confidence inte…