Farmland bird invertebrate food provision in arable crops

Abstract

Invertebrates are an essential food source for most farmland birds yet their relative abundance and biomass in the most commonly grown arable crops are poorly understood. Dvac suction sampling was used to determine the abundance, biomass and community composition of those invertebrate groups considered important in the diet of farmland birds for the commonest arable crops. Approximately 40 fields were sampled at the edge and mid‐field over 2 years in three different locations in England. In cereals, the fauna was primarily comprised of Araneae (10%), Coleoptera (30%) and Hemiptera (58%), whereas the oilseed rape fauna was dominated by Coleoptera (65%) and peas and potatoes by Hemiptera (89%). Beans contained a high proportion of Coleoptera (39%) and Hemiptera (49%). Aphididae were the most abundant family (20–86% of total), although in oilseed rape and beans, Chrysomelidae, Curculionidae and Nitidulidae formed ca 20% of the fauna. Aphids only formed a small proportion (7%) of the total biomass, except in peas (32%). Instead, Araneae, Carabidae, Heteroptera, Homoptera and Tipulidae formed much larger and more equal proportions. The highest abundance and biomass of invertebrates were recorded in cereals and least in potatoes. The Grey Partridge chick‐food index in all crops was only a half or less of the level required to ensure that chick survival is sufficient to maintain numbers of this red‐listed species. The total number of invertebrates, their biomass, diversity and the Grey Partridge chick‐food index were higher at the crop edge compared to mid‐field. Conservation measures are needed to help reverse the long‐term declines of invertebrates on farmland, which should include developing further invertebrate‐rich, agri‐environment scheme options and management techniques to encourage invertebrates considered important as bird food within arable crops.

Effects of supplemental winter feeding on House Sparrows (Passer domesticus) in relation to landscape structure and farming systems in southern Sweden

“…This is a result we would expect if resource separation resulting from farming specialization was important for population regulation. Farms in landscapes with mainly intensive crop farming may sustain sufficient seed availability during winter for House Sparrows that often forage in seed storage facilities, but provide relatively few insects important for chick rearing during breeding and thereby limit populations (Brickle et al 2000, Holland et al 2012. However, populations in mixed landscapes, with mainly animal husbandry, may have sufficient food supply during breeding (Moller 2001) but suffer from limiting mechanisms acting during the winter.…”

Continent‐scale global change attribution in European birds ‐ combining annual and decadal time scales

“…We used a nominal categorization of species' specialization to farmland habitats (Farm, http://www.ebcc.info/wpimages/other/SpeciesClassification2012.xls) and scored species for their main breeding and winter diet type using categories of insectivores ( I ), herbivores ( H ), and species with a mixed or omnivorous diet ( O ). The assignment was based on multiple published data sets (Bohning‐Gaese & Oberrath, ; Gregory et al ., ; Van Turnhout et al ., ; Holland et al ., ) and a review of the standard literature (Cramp et al ., ). Finally, log‐transformed average body length (logBody) was obtained from (Cramp et al ., ).…”

Scientific Opinion addressing the state of the science on risk assessment of plant protection products for non‐target arthropods

“…As could be expected, higher total numbers of invertebrates were to be found at the field edges than the mid-field. Strikingly, Holland et al (2012) demonstrated that, in all 40 common crop fields investigated in their study, the chick-food index was only half or less the level required to ensure sufficient chick survival for the maintenance of the population of the grey partridge. Frampton and Dorne (2007) quantified the impact of reduced PPP input on the abundance of several arthropod groups, including so-called 'chick-food insects'.…”

“…Next to the results of the investigations above, showing a strong decrease of NTAs as food web support in fields treated with PPPs, Holland et al (2012) investigated the NTA diversity and calculated the chick-food index in 40 agricultural fields, cultivated with cereals, oil seed rape, peas, beans or potatoes. As could be expected, higher total numbers of invertebrates were to be found at the field edges than the mid-field.…”