Joanna Czarnecka

Winter diet of Yellowhammers Emberiza citrinella on contemporary farmland: the different contribution of forbs, wild grasses and cereals in semi-natural and agricultural habitats

Capsule Composition of Yellowhammer diet differed significantly between two major habitat categories: semi-natural (fallow lands, abandoned grassland and road verges) and agricultural habitats (managed fields, stubble fields and manure heaps). Semi-natural habitats and winter stubble fields were important sources of non-cereal plant food and plant parts of cereals were the staple diet in fallow lands, managed fields and manure heaps. Aims To determine the composition of the winter diet and food niche of Yellowhammers feeding on various farmland habitat types characteristic of lowland agricultural areas in Central Europe. Methods Diet was determined on the basis of faecal sample analysis. Multivariate analysis of variance, principal component analysis and two measures of diversity (Shannon Diversity Index and Berger–Parker Index of Dominance) were used to assess the variation in contribution of various plant parts of dicotyledons (henceforth referred to as forbs), wild grasses and cereals in the diet. Results Dietary composition differed significantly between six types of farmland habitats, as well as between these habitats pooled into two major habitat categories: semi-natural and agricultural ones. Plant parts of cereals (grain fragments and husks) were the staple diet in fallow lands, managed fields and manure heaps and were the sole items consumed in crop fields. Plant parts of dicotyledon weeds were eaten almost exclusively in semi-natural habitats. The contribution of wild grasses was highest in stubble fields. The most diverse diet was in fallow lands (road verges > manure heaps > abandoned grasslands > stubble fields) and the most simple in managed fields. Overall diet diversity was positively correlated with the proportion of parts of forbs (dicotyledonous weeds) and negatively correlated with the proportion of pooled fragments of wild grasses and cereals. Conclusion Semi-natural habitats and winter stubble fields are important sources of non-cereal plant food for Yellowhammers. In particular, unpaved roads and fallow land support dicotyledonous weed seeds (Polygonum spp.), and manure heaps contain cereal plant food (probably both husks and seeds from the faeces of farm animals and straw used as litter in their bedding). Contemporary changes in weed communities as a consequence of intensification of agriculture that has reduced this flora to certain abundant nitrophilous species (e.g. Polygonum spp., Chenopodium album, Echinochloa crus-galli and Setaria spp.), the seeds of which are often consumed by Yellowhammers, can therefore increase the food resources of granivorous birds. A mosaic landscape with crop-free plots and microhabitats (with patches of permanent vegetation like road verges), stubble fields (with natural regeneration of annual weeds) and manure heaps enables Yellowhammers to find local feeding grounds, especially during periods of thick snow cover, when feeding sites or resources in open farmland are inaccessible.

Re-evaluation of the role of the grey partridge Perdix perdix as a disperser of arable weed seeds

AbstractThe endozoochorous dispersal of weed seeds, mediated by birds and without any adaptation to frugivory, has been studied very rarely. We studied the endozoochorous dispersal of viable seeds by the grey partridge Perdix perdix in agricultural landscape. We assessed the content of intact seeds in 609 grey partridge droppings coming from 21 sampling sites in Poland that included three land-cover types (winter cereals, winter oil-seed rape and stubble fields). We found 159 intact seeds of 13 plant species. Most of them are classified as plants without any evolved adaptations to dispersal. The number of intact seeds retrieved from droppings was positively correlated with the proportion of seeds and negatively correlated with total proportion of leaves in the diet. This result may indicate that the consumption of large numbers of seeds increases the possibility that some of them will resist digestion and be excreted with faeces. Our results showed that the highest number of intact seeds recovered from the droppings coming from stubble fields was the consequence of the importance of weed seeds in the diet of grey partridge in this type of land-cover. The grey partridge is a poor seed disperser and rather, it plays an important role as a predator of weed seeds.ZusammenfassungNeubewertung der Bedeutung des RebhuhnsPerdixperdixals Samenverbreiter von Ackerunkräutern Die Verbreitung von Unkrautsamen, die keine besondere Anpassung an Frugivorie zeigen, mittels der Aufnahme und Ausscheidung durch Vögel wurde bislang nur sehr selten untersucht. Wir untersuchten die Verbreitung keimfähiger Samen—nach der Darmpassage durch Rebhühner Perdixperdix—in der Ackerlandschaft. Wir bestimmten den Gehalt unversehrter Samen in 609 Proben Rebhuhnlosung von 21 Untersuchungsorten in Polen mit einer von drei Formen der Bodenbedeckung (Wintergetreide, Winterraps und Stoppelfelder). Wir fanden 159 intakte Samen von 13 Pflanzenarten. Die meisten von diesen gehörten zu Pflanzen ohne besondere evolutionäre Anpassungen bezüglich der Verbreitung. Die Anzahl unversehrter Samen in der Losung korrelierte positiv mit dem Anteil an Samen und negativ mit dem Anteil an Blättern am Nahrungsspektrum. Diese Ergebnisse könnten darauf hindeuten, dass der Verzehr einer großen Samenmenge die Wahrscheinlichkeit dafür erhöht, dass einige davon die Verdauung überstehen und mit dem Kot ausgeschieden werden. Unsere Ergebnisse zeigten, dass der hohe Anteil unversehrter Samen in der von den Stoppelfeldern stammenden Losung auf der Bedeutung der Unkrautsamen für die Ernährung der Rebhühner in diesem Vegetationstyp beruhte. Rebhühner sind schlechte Samenverbreiter und spielen eher eine wichtige Rolle als Vertilger von Unkrautsamen.

Endozoochorous dispersal of alien and native plants by two palearctic avian frugivores with special emphasis on invasive giant goldenrod Solidago gigantea

The role of frugivorous birds in dispersal of the seeds of fleshy-fruited plants is well understood, but other groups of birds like granivores and omnivores can also act as vectors, especially in the process of non-standard dispersal. In this study we examined the role of two widely distributed birds (the Eurasian Blackbird, Turdus merula, and the Black Redstart, Phoenicurus ochruros) in seed dispersal. We analyzed the content of 279 droppings of the Black Redstart collected between July and October and 85 droppings of the Eurasian Blackbird collected during January. In total we found 366 seeds, representing 11 plant taxa, in the faecal samples; 93% of the seeds belonged to fleshy-fruited species. The most numerous were two native taxa, Sambucus racemosa/nigra, in summer and autumn, Crataegus monogyna in winter, and one alien species Morus alba, which is dispersed in summer. We also found seeds of four dry-fruited species; the most interesting of which was the presence of anemochorous seeds of Solidago gigantea (a highly invasive alien species). The seeds were found only in droppings of the Eurasian Blackbird. Considering the obtained results the need for further studies on bird-plant interactions should be a priority.

Autumn–winter diet of Grey Partridges Perdix perdix in winter crops, stubble fields and fallows

Capsule Diet composition differed significantly between winter cereals, winter oil-seed rape, stubble fields and permanent fallows. Aims To determine the composition of the diet of Grey Partridges in autumn and winter in four agricultural land-cover types, characteristic of lowland areas of Central Europe. Methods Faecal analysis was used to determine diet. Multivariate analysis of variance (manova), Simpson Index of Diversity (sid) and Detrended Correspondence Analysis (dca) were used to assess variation in the proportions of the six main dietary components (cereal and broad-leaved plant leaves, weed seeds cases, cereal grains, husks of grasses and other plant material). Results Thirty-seven different kinds of plant food items were found, and the most numerous were cereal leaves (58.2% in total of all items), followed by leaves of broad-leaved plants (21.8%), weed seed cases (13.3%), cereals grains (3.5%), husks of grasses (1.2%) and other plant material (2.0%). Diet composition differed significantly between winter cereals, winter oil-seed rape, stubble fields and permanent fallows. The dca showed that the two first axes explain 38% of the total variance of the diet. The diet diversity was highest in stubble fields and permanent fallows, and the smallest in winter cereals. Dietary diversity was negatively correlated with the overall abundance of leaves, and positively with the abundance of weed seeds, cereal grains and husks of grasses. Conclusion Cereal leaves might replace other food items, which suggests that food resources are not a critical factor limiting the population of Grey Partridges during winter. A high proportion of weed seeds and cereal grains in the diet of Grey Partridges in stubble fields confirms the importance of these fields as sources of food of high-calorific value. Maintenance of stubble fields and cover crops with natural regeneration of annual weeds should constitute an important element of a strategy for the recovery of Grey Partridge populations in arable landscapes in Europe.

Food of Water Pipits Anthus spinoletta on wintering grounds in southwest Poland

Capsule Analysis of droppings revealed 56% animal items, 41% plant items and 3% mineral items.

The White Stork as an Engineering Species and Seed Dispersal Vector when Nesting in Poland

The white stork can affect plant population and community dynamics and structure in an agricultural landscape. It is a vector transporting large numbers of seeds along with nest material, and it is an ecosystem engineer which builds nests that function as specific habitats for plants. The following questions were asked: (i) What is the structure of the seed pool in the nest material? (ii) Can nests be treated as a habitat enabling plants to complete their life cycle? (iii) What is the probability that seeds produced in the nests reach suitable habitats in the nests’ closest vicinity? Seed pools of ten whitestork nests were analysed using the seedling germination method. The average number of seedlings detected in the nest material was 9937 per one nest (870 per 10 000 g of dry weight); they belonged to 97 taxa. Majority of the species present in the nests created persistent seed banks (62.5%); 62.2% of the seedlings represented annual species. Significantly higher percentage of weeds and significantly lower of woodland and peat-bog species in the nests as compared with the respective percentages of these species groups in the regional pool, indicated arable fields and ruderal sites as the main sources of seeds as well as the nest material. Since ruderal species and weeds dominated in the seed pool found in the nests, and such habitat types were most common in the vicinity of the nests, the probability that seeds produced in the nests would disperse into a suitable habitat was high.