Variation in the abundance of Blackcaps<i>(Sylvia atricapilla)</i>wintering in an Olive<i>(Olea europaea)</i>orchard in southern Spain

Santos, Manuel Rodríguez de los; Cuadrado, Mariano; Arjona, Salvador

doi:10.1080/00063658609476900

Cited by 16 publications

(8 citation statements)

References 15 publications

(13 reference statements)

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“…(I failed to detect this relationship in the data for the period 1978-1987, which encompassed a single fruiting event [Herrera 1988b].) ) Decoupling between annual variation in the abundance of fruits and of overwintering frugivores found in this study contrasts with the positive relationship previously suggested for other southern Spanish, Mediterranean, lowland localities (Jordano 1985, Rodríguez de los Santos et al 1986, Cuadrado et al 1995. Even in this case, however, the response of the frugivore was rather weak; extraordinary increases in abundance of the food resource brought about only modest increases in abundance of the consumer (Fig.…”

Section: Variation In Bird Abundancecontrasting

confidence: 75%

Long-Term Dynamics of Mediterranean Frugivorous Birds and Fleshy Fruits: A 12-Year Study

Herrera¹

1998

Ecological Monographs

193

292

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The relationship between fleshy-fruited plants and their vertebrate seed dispersal agents often has been depicted as subject to important interannual variation, but no study has thus far documented such variation on a long-term basis. This paper presents the results of a 12-yr investigation on fleshy-fruited plants and avian frugivores in a Mediterranean montane locality of southeastern Spain. The main objective was to document patterns and correlates of long-term variation in the composition and abundance of fruits and birds, with particular reference to seed dispersers. During October-December (''autumn'' period) 1978, abundance of ripe fruits and birds was assessed in a 4-ha plot in dense, well-preserved sclerophyllous scrub, by means of counts in permanent plots and mist-netting, respectively. Diet composition and fruit preference patterns of Erithacus rubecula and Sylvia atricapilla, the two most abundant seed dispersers, were also investigated over the same period, using fecal sample analyses. Possible consequences to the birds of annual variation in fruit supply and diet composition were investigated using data on fat deposition levels and recapture rates of mist-netted individuals.Total fruit abundance (i.e., mean ripe fruit density of all species combined) fluctuated among years between 5.4 Ϯ 11.1 fruits/m 2 (mean Ϯ 1 SD; 1986) and 77.1 Ϯ 78.0 fruits/m 2 (1989) and was positively related to the amount of rainfall in the preceding spring. Not all fruiting species bore ripe fruits every year, and among those species that did, fruit density fluctuated asynchronously and to variable degrees. Seven out of 13 species exhibited significant supra-annual periodicity in fruit abundance, with fluctuation periods ranging from 2 to 6 yr. Variation in the abundance of each of the six most abundant fruit species was unrelated to annual variation in rainfall. The autumn bird assemblage at the study site was made up of year-round resident species (54.1% of captures, all years combined) that were largely fruit predators (feeding on pulp or seeds without performing dispersal) and of autumn-winter resident species (45.5% of captures) that were largely seed dispersers. Bird abundance, all species combined, ranged between 27.1 and 61.5 captures/100 net-hours for 1987 and 1986, respectively. Depending on year, seed dispersers made up 25.6-75.4% of the total captures, and fruit predators made up 20.9-69.7%. The relative importance of nonfrugivores was always negligible (1.1-9.9%). No correlation existed across years between total fruit abundance and the capture rates of all bird species combined, seed dispersers, or fruit predators. Annual variation in the abundance of seed dispersers was positively related to November mean maximum temperature. At the individual species level, S. atricapilla capture rates were correlated with the abundance of the fruits of Phillyrea latifolia, a species exhibiting extreme annual fluctuations.Annual variation in the importance of fruits in the diet of S. atricapilla and E. rubecula was not signi...

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Section: Variation In Bird Abundancecontrasting

confidence: 75%

Long-Term Dynamics of Mediterranean Frugivorous Birds and Fleshy Fruits: A 12-Year Study

Herrera¹

1998

Ecological Monographs

193

292

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“…However, fruit size of commercial olives has been increased via artificial selection, resulting in fruits too large to be swallowed by most frugivores (Rey 1992(Rey , 1993. These birds consume cultivated olives by pulp-pecking (Tutman 1969;Tejero, Camacho & Soler 1983; Rodríguez de los Santos, Cuadrado & Arjona 1986;Debussche & Isenmann 1990;Rey & Gutiérrez 1996). This system constitutes a valuable opportunity to test the predictions formulated above by comparing the feeding behaviour of frugivorous birds on cultivated olive trees ('experimental' conditions) and wild olive trees ('control').…”

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confidence: 99%

Fruit size in wild olives: implications for avian seed dispersal

et al. 1997

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1. The response of frugivorous birds to an enlargement of fruit size, and the consequences for both birds and plants, are analysed for the interaction between avian seed dispersers and olives (Olea europaea). 2. The enlargement of fruit size promotes a shift in frugivorous birds’ feeding behaviour, from swallowing fruits whole to pecking pieces of pulp. The relative frequency of olive consumption using each feeding behaviour was assessed by combining field data on frequency of appearance of olive pulp and seeds with data from laboratory trials. 3. Sardinian Warblers (Sylvia melanocephala) and European Robins (Erithacus rubecula) were mainly peckers both on cultivated and wild olives. Blackcaps (Sylvia atricapilla) consumed wild olives mainly by swallowing but consumed cultivated olives (larger than the wild ones) primarily by pecking. Song Thrushes (Turdus philomelos) were primarily swallowers of both types of fruits. 4. Laboratory trials with Song Thrushes, Blackcaps and European Robins showed that: (a) all were able to peck fruits; (b) fruit size determined a shift from swallowing to pecking, as pecking frequency increased with the enlargement of the fruit size; (c) all the species had an increased fruit handling failure rate when trying to swallow increasingly large fruits; and (d) from the birds’ perspective, small shifts in fruit size may have important consequences on fruit profitability. 5. Pecking on olives turns the mutualistic fruit–frugivore interaction into a fruit‐pulp predator interaction, thus arising a conflict between the plant and frugivorous birds. 6. This study shows that heavy dependence on fruit is not always simply related to seed dispersal. The same frugivorous bird species can act as a seed disperser or a pulp predator for the same plant species. The threshold between these roles is highly influenced by the ratio gape size/fruit size.

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“…However, in the southern Mediterranean, olives are still very abundant and they are heavily consumed (e.g. Tejero et al 1984, Rodriguez de los Santos et al 1986. Besides the availability in high densities on large areas, two other traits have magnified their importance: their availability during winter at a period where other fruits are scarce and their high lipid profitability, much higher than that observed in the most fatty spontaneous fruits (Anacardiaceae) (Figure 4).…”

Section: Dispersal Successmentioning

confidence: 96%

“…Such an habitat switch is also obvious for the Blackcap which, contrarily to more polyphagous bird species, occurs in numbers in urbanized areas with ornamental gardens during winter and early spring (Figure 3). Furthermore the nomadism of the Blackcaps is frequently suspected to be linked with its high dependence on fruits (Morel & Roux 1966, Sultana 1972, Finlayson 1980, Debussche & Isenmann 1984, Rodriguez de los Santos et al 1986. It is likely that abundant crops of fleshy fruits have a sound influence on the migrating and wintering patterns of frugivorous birds.…”

Section: Behaviour Of the Frugivorous Speciesmentioning

confidence: 97%

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Introduced and cultivated fleshy-fruited plants: consequences of a mutualistic Mediterranean plant-bird system

Debussche¹,

Isenmann²

1990

Biological Invasions in Europe and the Mediterranean Basin

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The Montpellier region (Mediterranean France) offers 65 native taxa with fleshy fruits whose seeds are dispersed mainly by bird species. Birds also remove the fleshy fruits of non-native plant species, cultivated ones (e.g. Vitis vinifera ssp. vinifera), weeds (e.g. Phytolacca americana), garden shrubs (e.g. Pyracantha coccinea, Ligustrum ovalifolium). We report that 19 non-native plant species are dispersed by 16 bird species. Grapes constitute a very importand food item for migrating and wintering thrushes (mainly Turdus phi/omelos and T. iliacus) and are as important as fruits of wild plants (Juniperus sp. pl.) in their diet. pyracantha coccinea, and subsidiarily other garden shrubs (e.g. Cotoneaster sp. pI., Ligustrum ovalifolium) attract small passerines, predominantly Blackcaps (Sylvia atricapilla), during winter and at the beginning of spnng.The diet of the Blackcap, a nearly exclusive frugivorous bird in autumn and winter, shows a significant trend from native to introduced fruits from summer to early spring, as the availability in native fruits progressively becomes more scarce. At the same time their populations are concentrated in villages and suburban gardens where crops of ornamental plant species persist for a long time. On the other hand, the diet of the European Robin (Erithacus rubecula) which is less dependent on fruits, does not show the same shift and their populations do not move to more anthropic areas.We suggest that the abundant crops provided by cultivated and ornamental plants may change the migrating and wintering behaviour of the fruit dependent bird species, allowing some of them to winter in more northern or different regions than they formerly used to do.Only 6 out of 19 listed plant-species can be considered as naturalized, but no one is actually invasive. We think that this absence of invasion success must be linked with several regional features, i.e. (1) climatic stresses (frost and drought), (2) edaphic constraints (calcareous soils), (3) landscape composition (predominance of wooded areas) and (4) richness in native fleshyfruited species which offer large crops and a wide spectrum of availability, Castri, A. J. Hansen and M. Debussche (eds.)

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Variation in the abundance of Blackcaps(Sylvia atricapilla)wintering in an Olive(Olea europaea)orchard in southern Spain

Cited by 16 publications

References 15 publications

Long-Term Dynamics of Mediterranean Frugivorous Birds and Fleshy Fruits: A 12-Year Study

Long-Term Dynamics of Mediterranean Frugivorous Birds and Fleshy Fruits: A 12-Year Study

Fruit size in wild olives: implications for avian seed dispersal

Introduced and cultivated fleshy-fruited plants: consequences of a mutualistic Mediterranean plant-bird system

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