Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 6

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  granivorous bird
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1

Grains in the diets of medium-sized carnivores – a case of diplochory?

100%
Kurek P., Holeksa J.
Polish Journal of Ecology
|
2015
|
tom 63
|
nr 2
Although most grasses (including cereals) are described as epizoochoric or anemochoric, many authors have shown that grains may be dispersed via the digestive tracts of animals, i.e. are endozoochoric. Cereals have been reported from carnivores' faeces several times; nevertheless, there is no data about the fate (i.e. capacity to germinate) of these grains. The scope of this paper is to focus on the role of medium-sized carnivores as potential secondary dispersers of grains. In 2010–2011, we examined 619 faeces of badgers Meles meles, foxes Vulpes vulpes and martens Martes sp. Faeces were collected every month from June to November in Kampinos National Park (KNP). In seven cases (1.1%) we found 64 grains of a total of two species of cereals: rye, Secale cereale and oats, Avena sativa, in the faeces of red fox and martens, with the red fox samples predominant. Some of the seeds retained the capacity to germinate and to establish seedlings. In two cases, included as accompanying material, feathers of a bird were found, which may suggest secondary dispersal of cereals via carnivores' guts.
2

The decline of the Bullfinch Pyrrhula pyrrhula in Britain: is the mechanism known?

100%
Siriwardena G. M., Freeman S. N., Crick H. Q. P.
Acta Ornithologica
|
2001
|
tom 36
|
nr 2
The Bullfinch has declined in Britain and elsewhere in Europe, but definitive evidence about the cause and demographic mechanism has yet to be published. We review current knowledge, concentrating on analyses of demography, and present new integrated population modelling analyses designed to reveal the demographic changes most important in the decline. It is likely that changes in brood size and clutch size have not been important and our models suggest that the decline can be explained without invoking variation in numbers of breeding attempts or post-fledging survival rates. However, although changes in the egg period daily nest failure rate provide the best explanation for population change during the years of steepest decline, nestling period failures, adult survival and first-year survival could all have been equally important. Egg period nest failure rates have been higher in the preferred habitat, woodland, than in farmland and have fallen over time in farmland, where a larger decline has occurred (65% versus 28%), arguing against a causal link with abundance. Despite evidence for a negative effect of agricultural intensification on Bullfinch presence, little evidence exists clearly linking any demographic rate to environmental change and agricultural land-use has had little effect on nest failure rates. Predation appears to have had no significant impact. Future work should focus on contemporary investigations of the importance of hedgerow structure and woodland understorey vegetation.
3

Granivory of birds and seed dispersal: viable seeds of Amaranthus retroflexus L. recovered from the droppings of the Grey Partridge Perdix perdix L.

80%
Orlowski G., Czarnecka J.
Polish Journal of Ecology
|
2009
|
tom 57
|
nr 1
191-196
The droppings of the Grey Partridge Perdix perdix L. wintering on a set-aside field were found to contain 99.3% of Amaranthus retroflexus and 0.7% of Chenopodium album seed coat fragments. A bird consumed on average 3008 (± 95% CL = 2699–3317) weed seeds per 1 g of droppings. The excreted seed coat remnants made up c. 21% of the swallowed seed mass. Approximately 0.3% of the ingested seeds passed undamaged through the gut. The number of undamaged seeds in the droppings was not significantly correlated with the weight of droppings and the amount of the excreted sand grains, seed coat fragments and other plant parts. After over 1.5 years of storage, 3 out of 18 sown undamaged seeds of A. retroflexus germinated. The average germination time of the excreted seeds was 10 days, while for the fresh ones it amounted to 8.5 days. Our results shows that the Gray Partridge is poor seed disperser and it play important role as predator of A. retroflexus seeds.
4

Seed predation on the ground or in the tree? Size-related differences in behavior and ecology of granivorous birds

80%
Parea R., Venturas M., Gil L.
Acta Ornithologica
|
2014
|
tom 49
|
nr 1
Seed-eating birds may consume seeds in the tree (pre-dispersal predation) as well as on the ground (post- dispersal predation), usually at contrasting microhabitat conditions. We examined the foraging behaviour and contribution to seed predation of a whole assemblage of seed-eating birds (mostly Fringillidae) at both dispersal phases (pre- and post-dispersal) in a wind-dispersed tree, the European White Elm Ulmus laevis. We found that most seed predators were tree-feeding birds that prey upon seeds for longer periods in the tree and spend shorter periods in larger flocks foraging on the ground. We also obtained significant differences in predation speed among the seed predator species. The overall number of seeds consumed by birds, as well as the amount of time spent foraging in the tree, increased with increasing feeding heights. Seed availability increases with height, which seems to be the main reason why birds spend more time foraging on higher branches. Birds strongly differed in their perching coefficient (PC, ration of feeding height to distance from crown edge). Small finches such as Serins Serinus serinus and Goldfinches Carduelis carduelis had a very high value of PC in comparison to large finches such as Greenfinches Carduelis chloris, Chaffinches Fringilla coelebs, and Hawfinches Coccothraustes coccothraustes. In general, finches showed much higher values of PC than non-fringillid species, indicating a greater adaptation to perch and feed on more flexible stems. Birds increased their overall seed predation and the time allocated to foraging on the ground when they were in flocks. Small finches tended to follow larger finches and flock in multispecies groups when foraging on the ground. We suggest that this behaviour increases both feeding efficiency and safety. Further studies should take into account possible differences in behavior of seed-eating birds throughout the dispersal season since it may have important implications for their adaptive behavior to select new niches.
5

Foraging habitat requirements of European Turtle Dove Streptopelia turtur in a Mediterranean forest landscape

80%
Gutierrez-Galan A., Sanchez A. L., Gonzalez C. A.
Acta Ornithologica
|
2018
|
tom 53
|
nr 2
Land use changes occurring in Europe in recent decades are generating important changes in the forest landscape characteristics and are having important effects on avian species richness and abundance. This is particularly important for some bird species of particular conservation concern that require heterogenous landscapes where breeding habitats are proximal to foraging habitats. Among these birds, the European Turtle Dove Streptopelia turtur is particularly important because of its marked population decline. In southern Europe, forest landscapes have been considered important breeding areas for Turtle Doves. We assessed the influence of the foraging area characteristics — distance to cereal crops and wild seed species abundance — and water availability on Turtle Dove breeding habitat suitability in a Mediterranean forest landscape in southern Spain. Forty-six point locations were surveyed during the spring of 2014 and 2015 on two nearby farms of a forest protected area. The average local abundance of Turtle Doves found at each point location was 1.25 ± 1.31 males, and it was significantly higher at the point locations closest to cereal crops, as well as at nesting sites where the wild seed species included in its local diet were abundant, especially Echium plantagineum. Distance to water in the studied range (average distance 475 m) did not show a significant effect on Turtle Dove local abundance, although the high availability of water in the study area could have a positive influence on the overall Turtle Dove breeding habitat suitability. To benefit Turtle Dove breeding habitat suitability, cultivated areas with cereals/legumes near those forest areas where Turtle Doves reproduce should be promoted. Likewise, the promotion of those herbaceous species that are locally important in the Turtle Dove diet, available, for example, through specific grazing management, should be taken into account when nesting habitat restoration is designed in forest areas, regardless of whether the distances to food resources are long.
6

Habitat use by breeding and wintering reed bunting Emberiza schoeniclus L. in farmland of Lower Silesia [SW Poland]

80%
Orlowski G.
Polish Journal of Ecology
|
2005
|
tom 53
|
nr 2
Studies on the habitat preferences of Reed Bunting Emberiza schoeniclus L. conducted on an intensively farmed (93% arable land) area (54 km²) of Wrocław Plain (Lower Silesia Province, SW Poland, 17°03’E, 51°02’N) have shown that during the breeding season this species was found mainly in abandoned crop fields profusely overgrown with Tanacetum vulgare, Artemisia vulgaris and Solidago sp. Wintering birds remained in strongly weeded crops (arable habitats). The presence of breeding pairs (n = 37) was recorded within 24 (36%) out of the 67 longterm fallows (total area = 336.88 ha, average area = 5.03 (± 10.52 SD) ha, range = 0.19 to 83.53 ha). The field size was the best predictor of the Reed Bunting abundance among the seven landscape variables describing the environmental diversity of a fallow (apart from the field size, these were the lengths of: treebelts, hedges, railway embankments, roads, ditches and borders with adjacent crop fields). In the model of multiple regression after stepwise forward selection this variable explained as much as 86% of the variance in Reed Bunting abundance in that biotope. Wintering birds (total of 367 specimens) were discovered in 43 (37%) out of the 117 studied fields, comprising seven arable habitats – cereal stubbles, young and old fallows, root crop stubbles, fruit and vegetable crops, bare tilled and winter cereals (average area = 2.81 (± 2.31), range = 0.23 to 12.72 ha). The highest density and frequency (i.e. percentage of one field type where at least one Reed Bunting was recorded) were found in strongly weeded fruit and vegetable crops and in root crop stubbles (with abundant Amaranhtus retloflexus, frequency respectively 89 and 64%), in young fallows (with a series of annual weed species, including the abundant Chenopodium album; 77% frequency) and in cereal stubbles (with Chenopodium album and Setaria viridis; 50% frequency). In winter season birds were recorded only in 20% of old fallows. No wintering birds were found in winter cereals, nor in ploughed fields. The large area of root crops in Poland and the related spreading of weeds, such as Amaranthus and Chenopodium, coupled with long-term set-aside may compensate many granivorous birds, wintering in Europe on farmland, for the considerable reduction in their winter food resources, caused by the massive introduction of winter cereals.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.