Population declines in many farmland bird species have been documented during the last quarter of the 20th century in parts of Europe and North America where agricultural intensification has been most marked. ‘Intensification’ is multivariate, difficult to define precisely, but taken to subsume all those advances that have allowed farmers to increase primary productivity. Increased pesticide use on arable land has been a key cause of Grey Partridge Perdix perdix decline through its impact on the availability of insect foods to chicks, and hence on reproductive success.
Blog
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Linking agricultural practice to insect and bird populations: a historical study over three decades
There is continuing debate about the impact of agricultural practices on farmland wildlife. In particular, it has been postulated that a general decline in insect abundance linked with intensification of agriculture may have contributed to farmland bird decline. While some autecological studies have supported this hypothesis, larger-scale and long-term studies are needed.
• Suction traps mounted on 12·2-m towers (Rothamsted-type) have been sampling aerial insects for nearly 40 years throughout the UK. Their catches are correlated over large spatial scales. We analysed insect catch data from a single suction trap run for 27 years in a rural location in Scotland, and showed that insect numbers have changed significantly over time, although non-linearly. The multivariate data set (numbers from the 12 common arthropod groups) was summarized using principal components analysis (PCA) to extract three components explaining 62% of the variation.
• We also used PCA to describe agricultural change, using published agricultural data for eight measures of farming in Scotland. Arthropod abundance and principal component (PC) scores were significantly related to the agricultural PC scores as well to summary climatic measures.
• Using Scottish data from the British Trust for Ornithology Common Birds Census, we extracted three PC to describe the time-dependent average densities of 15 common farmland birds in Scotland. Measures of bird density were significantly related to insect abundance and PC scores and, independently, to measures of agriculture and climate.
• These data from a broad suite of species provide support for linked temporal change between farmland birds, invertebrate numbers and agricultural practice in Scotland. Although entirely correlative, the results are consistent with the view that agricultural change has influenced birds through changes in food quality or quantity. The work also shows how large-scale invertebrate sampling, in this case using suction traps, is useful for monitoring farmland biodiversity.
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Insect crash at root of House Sparrow decline
Britain’s House Sparrow Passer domesticus population has declined by 68 percent since 1977. Though still relatively plentiful in small towns in the countryside and by the sea, the bird has disappeared in many major conurbations, including central London, where the species has virtually vanished. House Sparrows are also disappearing from Bristol, Edinburgh, and Dublin, as well as Hamburg, Prague, and Moscow. Now, according to a scientific paper to be published in a forthcoming issue of the journal Animal Conservation, there’s a compelling theory for why: insect decline.
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Rapid declines of British moths provide evidence of an insect biodiversity crisis
A fundamental problem in estimating biodiversity loss is that very little quantitative data are available for insects, which comprise more than two-thirds of terrestrial species. We present national population trends for a species-rich and ecologically diverse insect group: widespread and common macro-moths in Britain. Two-thirds of the 337 species studied have declined over the 35 yr study and 21% (71) of the species declined >30% 10 yr−1.
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40,000 ‘splatometers’ can’t be wrong: insect population is in decline
Nearly 40,000 conservation-minded drivers counted the bugs splattered on their vehicle number plates this summer, the Royal Society for the Protection of Birds (RSPB) announced yesterday. The motorists were helping the world’s first mass survey into possible insect decline, a UK-wide Big Bug Count held throughout June, and the initial results appear to confirm suspicions that insect numbers have fallen, the RSPB said.
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Significant decline in flying insect abundance in Hereford area of Southern Britain
For the first time, long-term changes in total aerial insect biomass have been estimated for a wide area of Southern Britain. From 1973 to 2002, there was a significant decline in total biomass at Hereford. The Hereford samples were dominated by large Diptera, particularly Dilophus febrilis, which showed a significant decline in abundance. Diptera have been identified as important in the diets of adult and chicks across a range of species. The declines shown in Hereford are thus likely to have had some effect on the bird populations of the surrounding area.
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Extreme Normoverschrijdingen van Imidacloprid in Nederlands oppervlaktewater in 2007
Onlangs gaven de waterschappen en waterbeheerders nieuwe meetgegevens vrij over imidacloprid in Nederlands oppervlaktewater. De toestand is zeer alarmerend: ook in 2007 zijn in het westen van Nederland extreme normoverschrijdingen van imidacloprid in het oppervlakte water gemeten. De hoogste gemeten imidacloprid concentratie (15 maart 2007) overschreed meer dan 4.000 keer de (ad hoc) MTR (maximaal toelaatbaar risiconiveau) norm voor oppervlaktewater. Veel normoverschrijdingen in de Randstad liggen veel hoger dan de imidacloprid concentraties die in laboratorium studies binnen enkele dagen sterfte van insecten veroorzaken.
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The decline of the birds and the bees – Rachel Carson’s Silent Spring revisited
Monitoring data reveal significant changes in the number of meadow birds in the Netherlands. The overall yearly decline has nearly quadrupled in recent years, i.e. from 1.2% in 1990-2000 to 4.6% since 2000. All meadow birds in the monitoring scheme (Skylark Alauda arvensis, Northern Shoveler Anas clypeata, Yellow Wagtail Motacilla flava, Oystercatcher Haematopus ostralegus, Black-tailed Godwit Limosa limosa, Northern Lapwing Vanellus vanellus, Common Redshank Tringa totanus, Meadow Pipit Anthus pratensis en Tufted Duck Aythya fuligula) are declining since 2000. Songbirds like Skylark, Meadow Pipit and Yellow Wagtail declined up to 30% from year to year in some regions which may lead to a population drop of 75% in only five years. Particularly alarming is the steep decline of meadow birds in the western peat land of the Netherlands (with an overall annual decline of 13% since 2000). The bird decline observed since the nineties correlates well with the increasing use of imidacloprid, which was first introduced in agriculture in 1994 and is now by far the most widely used insecticide. Imidacloprid is may leach from soil and is a major surface water pollutant in the Netherlands, particularly in the western part of the country.
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Het Nederlandse oppervlaktewater is zwaar belast met insecticiden
In een aantal artikelen is per regio of provincie een overzicht gegeven van oppervlaktewaterverontreiniging met insecticiden, gebaseerd op metingen van waterschappen en waterbeheerders verzameld in de Bestrijdingsmiddelenatlas. Het beeld dat naar voren komt is dat in het overgrote deel van Nederland de zware belasting van het oppervlaktewater met insecticiden (imidacloprid, organofosfaten en carbamaten) een acute bedreiging vormt voor insecten. Bijen, hommels, dagvlinders, libellen en waterjuffers dreigen daardoor uit te sterven in ons land. Alleen al de gemeten imidacloprid concentraties in het oppervlaktewater van de Randstad veroorzaken in laboratorium onderzoek binnen enkele dagen sterfte van honingbijen. De hoogste gemeten imidacloprid concentratie in het oppervlaktewater van de Bollenstreek zou in een laboratorium studie binnen enkele uren dodelijk zijn voor honingbijen.
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De milieuverontreiniging met imidacloprid veroorzaakt insectensterfte en verklaart uitsterven van vogelsoorten
Recentelijk toonde de Nederlandse toxicoloog Henk Tennekes aan dat de blootstellingstijd een versterkende werking op de toxiciteit van imidacloprid en thiacloprid voor ongewervelde dieren heeft (zie bijlage). Er is sinds 2004 sprake van zware oppervlaktewater verontreiniging met imidacloprid, die vooral in het westen van Nederland goed gedocumenteerd is (zie bijlage). Er zijn sterke aanwijzingen dat chronische blootstelling aan imidacloprid sterfte van ongewervelde dieren veroorzaakt. De achteruitgang van ongewervelde dieren heeft ook rampzalige gevolgen voor vogels, omdat een onmisbare eiwitbron voor het groot brengen van hun kuikens steeds schaarser wordt. Uit onderzoek van de Universiteit Utrecht bleek dat Diptera (vliegen en muggen) schaarser worden naarmate de concentraties van imidacloprid in het oppervlaktewater toenemen. Deze waarneming zou kunnen verklaren waarom de achteruitgang van zwaluwen (gespecialiseerd in het vangen van insecten in volle vlucht) zowel in Europa als ook in Noord Amerika dramatische vormen heeft aangenomen sinds de invoering van imidacloprid. Het ultieme bewijs voor de bepalende rol van het neonicotinoide insecticide imidacloprid bij de bijenvolksterfte (tabel 5 in de bijlage) wordt geleverd met een wiskundige vergelijking, die het verband beschrijft tussen de blootstellingsconcentraties en blootstellingstijd totdat een dodelijke werking optreedt. Als je dus weet met hoeveel imidacloprid de nectar en het stuifmeel (dat was meegenomen naar de bijenkast) besmet waren, kun je uitrekenen na hoeveel tijd bijensterfte zal optreden. Dat bleek in het onderhavige geval binnen 14 dagen te zijn. Aangezien winterbijen een levensverwachting van enkele maanden hebben, betekent daze dodelijke werking dus gegarandeerd het einde van een bijenvolk.