Population Dynamics and Social Behavior of the Mistle Thrush<i>Turdus viscivorus</i>During Winter

Skórka, Piotr; Wojcik, J.

doi:10.3161/068.040.0109

Cited by 16 publications

(12 citation statements)

References 19 publications

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“…The reason for the decrease in the number of mistletoe plants with an increase in stem competition is most likely related to the behaviour of Mistle Thrushes ( Turdus viscivorus ), the most common bird species that feeds on mistletoe fruits and disperses mistletoe seeds [ 39 ] in Central Europe. These birds not only feed on mistletoe fruits but, from autumn to early spring, they also defend selected mistletoe-infected trees from other birds [ 40 ]. They preferentially select free-standing trees because they are easier to protect [ 41 ].…”

Section: Discussionmentioning

confidence: 99%

Mistletoe Infection in an Oak Forest Is Influenced by Competition and Host Size

et al. 2015

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Host size and distance from an infected plant have been previously found to affect mistletoe occurrence in woody vegetation but the effect of host plant competition on mistletoe infection has not been empirically tested. For an individual tree, increasing competition from neighbouring trees decreases its resource availability, and resource availability is also known to affect the establishment of mistletoes on host trees. Therefore, competition is likely to affect mistletoe infection but evidence for such a mechanism is lacking. Based on this, we hypothesised that the probability of occurrence as well as the abundance of mistletoes on a tree would increase not only with increasing host size and decreasing distance from an infected tree but also with decreasing competition by neighbouring trees. Our hypothesis was tested using generalized linear models (GLMs) with data on Loranthus europaeus Jacq., one of the two most common mistletoes in Europe, on 1015 potential host stems collected in a large fully mapped plot in the Czech Republic. Because many trees were multi-stemmed, we ran the analyses for both individual stems and whole trees. We found that the probability of mistletoe occurrence on individual stems was affected mostly by stem size, whereas competition had the most important effects on the probability of mistletoe occurrence on whole trees as well as on mistletoe abundance. Therefore, we confirmed our hypothesis that competition among trees has a negative effect on mistletoe occurrence.

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Section: Discussionmentioning

confidence: 99%

Mistletoe Infection in an Oak Forest Is Influenced by Competition and Host Size

et al. 2015

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“…We also found that individuals spent more time in patches with a higher density of food. This was well documented for other fruit-eating birds (Sherman and Eason 1998;Johnson and Sherry 2001;Kwit et al 2004;Marshall and Cooper 2004;Sko´rka and Wo´jcik 2005). Fieldfares were very aggressive towards different species.…”

Section: Discussionmentioning

confidence: 87%

“…Fruit defence associated with territoriality is generally a very rare phenomenon in wintering birds (Willson 1986), but has been noted in a few thrushes (Turdidae). The best known examples are the mistle thrush Turdus viscivorus, fieldfare T. pilaris, and robin Erithacus rubecula, which form winter territories in places with abundant berries and defend them as long-term resources (Snow and Snow 1988;Cuadrado 1995;Walasz 2000;Sko´rka and Wo´jcik 2005).…”

Section: Introductionmentioning

confidence: 99%

Winter territoriality and fruit defence by the fieldfare (Turdus pilaris)

et al. 2006

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During the winter seasons of 2000/2001 and 2003/2004, 27 territorial fieldfares Turdus pilaris were observed in two study areas in southern Poland. Of these, 22 were in gardens or orchards with apple trees. Only 0.5% of all fieldfares noted during field surveys were territorial, and only 1.7% of the checked gardens and orchards were inhabited by that species. Fieldfares defended fruit against several species, including conspecifics. The probability of the presence of territorial fieldfares within a habitat patch was higher in patches with a higher density of apples, but was not related to the size or degree of isolation of the patch. The duration of holding territory was positively correlated with apple density and negatively correlated with the presence of intruders (mainly flocks of non-territorial fieldfares). The results suggest that food density and the presence of intruders are key factors affecting the presence of territorial thrushes during winter.

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“…Thrushes were major fruit consumers for all study years, the Mistle Thrush ( Turdus viscivorus ) being the most frequent species. These territorial birds frequently use parasitized trees as watchtowers to defend patches of abundant fruit densities from conspecifics or other fruit consumers (Snow & Snow ; Skórka & Wójcik ). By visiting parasitized trees more preferably (Fig.…”

Section: Discussionmentioning

confidence: 99%

Spatial heterogeneity of a parasitic plant drives the seed‐dispersal pattern of a zoochorous plant community in a generalist dispersal system

Mellado

Zamora

2015

Functional Ecology

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Summary Biota plays a central role as sources of spatial heterogeneity, having great potential to define ecological processes and patterns in the landscape. Mistletoes are fleshy‐fruited parasitic plants that dwell in forest canopies showing a strong aggregated spatial distribution. Parasitized trees potentially concentrate frugivore activity on their canopy, where birds find food, places to perch and protection against predators. Thus, seed‐deposition patterns generated from the canopy are expected to reflect the heterogeneity associated with the parasite. This becomes especially important in generalist dispersal systems; however, so far, we do not know the implications of mistletoe spatial heterogeneity on the seed‐dispersal pattern of other plants with which they simultaneously fruit. In a Mediterranean pineland, we analyse the impact of Viscum album subsp. austriacum on the seed‐deposition pattern of a zoochorous plant community, taking into consideration the spatial and temporal variability of environmental factors influencing the frugivore's habitat use, such as fruit availability and forest tree density. For four consecutive years, we studied 55 pairs of trees parasitized and unparasitized by mistletoe, analysing zoochorous fruit availability, frugivore visits and the zoochorous seed rain in selected trees. As expected, frugivorous birds responded to mistletoe heterogeneity by visiting parasitized trees preferentially to unparasitized ones, generating a differential deposition of mistletoe seeds on tree branches while dispersing seeds of co‐fruiting species under the host canopy. Availability of understory fruits remained similar in patches of parasitized and unparasitized trees, but showed strong temporal fluctuations reflected in the seed rain. On the other hand, mistletoe proved more copious in patches of parasitized trees and their fruit crops varied little between years, making mistletoes reliable food resources likely to lead to consistency in fruit‐deposition patterns. In conclusion, mistletoes, by patchily growing on the canopy layer and concentrating zoochorous seeds underneath, can shape the spatial seed‐deposition pattern of fleshy‐fruited plants in the forest. Moreover, as seeds constantly reach the same deposition sites over long periods, the soil beneath the host canopy could become hotspots for community regeneration. In degraded areas, such mistletoe effects might be critical, possibly promoting recolonization and vegetation recovery through the frugivore's activity.

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Population Dynamics and Social Behavior of the Mistle ThrushTurdus viscivorusDuring Winter

Cited by 16 publications

References 19 publications

Mistletoe Infection in an Oak Forest Is Influenced by Competition and Host Size

Mistletoe Infection in an Oak Forest Is Influenced by Competition and Host Size

Winter territoriality and fruit defence by the fieldfare (Turdus pilaris)

Spatial heterogeneity of a parasitic plant drives the seed‐dispersal pattern of a zoochorous plant community in a generalist dispersal system

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