Does frugivory by European starlings (Sturnus vulgaris) facilitate germination in invasive plants?<sup>1</sup>

LaFleur, Nancy; Rubega, Margaret A.; Parent, J.D.

doi:10.3159/08-ra-111.1

Cited by 23 publications

(16 citation statements)

References 40 publications

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“…The greater germination rates of A. cyclops seeds that had passed through the gut of Red‐winged Starlings in South Africa concur with the results of Impson (), and other studies reporting improved seed germination rates after passage through the gut of starlings (Spiegel & Nathan , LaFleur et al . ).…”

Section: Discussionmentioning

confidence: 97%

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The potential for birds to disperse the seeds of Acacia cyclops, an invasive alien plant in South Africa

Mokotjomela

Hoffmann

Downs

2015

Ibis

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Rooikrans Acacia cyclops is an aggressive invasive tree that threatens natural resources in South Africa. The seeds of A. cyclops have a prominent aril which attracts birds that ingest the seeds and disperse them endozoochorously. Two biological control agents, a Seed Weevil Melanterius servulus and a Flower‐galling Midge Dasineura dielsi, were released on A. cyclops in 1991 and 2002, respectively. Together these agents have substantially reduced seed production and generally far lower numbers of seeds are now available to birds. A consequence of this transition from historically bounteous quantities of seeds to scanty seed availability is that birds may no longer associate with the trees and seed dispersal may be disproportionately reduced. To assess whether this has happened, seed attrition was measured by comparing the amount of seeds that disappeared from two groups of branches, one available to birds and the other enclosed in bird netting. Other types of granivores (mainly field mice) were excluded from both groups of branches with a plastic funnel placed around the stems. Mature seeds were also harvested and fed to caged bird species to determine gut retention times and germination rates of ingested seeds. Attrition rates of seeds showed that birds continue to remove seeds but that only a proportion of the crop is taken. Only two frugivorous species (Knysna Turaco Tauraco corythaix and Red‐winged Starling Onychognathus morio) and two granivorous species (Red‐eyed Dove Streptopelia semitorquata and Laughing Dove Streptopelia sengalensis) ingested A. cyclops seeds during feeding trials. Ingestion by birds enhanced seed germination except for those ingested by Laughing Doves. There were no apparent effects of length of gut passage time and avian body size on seed germination rates. Despite the diminished seed resource due to biological control agents, birds continue to disperse A. cyclops seeds.

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Section: Discussionmentioning

confidence: 97%

“…Although germination may be enhanced by passage through a bird's gut, it may also remain unchanged or even be suppressed (Traveset , LaFleur et al . , Jordaan et al . , Mokotjomela , Chama et al .…”

mentioning

confidence: 99%

The potential for birds to disperse the seeds of Acacia cyclops, an invasive alien plant in South Africa

Mokotjomela

Hoffmann

Downs

2015

Ibis

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“…Many studies show that germination is more successful after seeds pass through the digestive tract of frugivores (Traveset 1998;Yagihashi et al 1999;Traveset et al 2001;Paulsen and Hogstedt 2002;LaFleur et al 2009;D'Avila et al 2010;Reid and Armesto 2011;Jordaan et al 2011a). Seed ingestion by dispersers helps seeds escape predation, competition, and fungal attack under the parent tree, thereby increasing the chance of survival (Chimera and Drake 2010;Fedriani et al 2011;Jordaan et al 2011a).…”

Section: Introductionmentioning

confidence: 98%

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

et al. 2015

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Avian frugivores play a key role in seed dispersal of many plant species, including invasive alien plants. We assessed the effect of gut passage on the germination of selected invasive alien plant species in South Africa. Fruits of four fleshly-fruited invasive alien plant species: Solanum mauritianum, Cinnamomum camphora, Psidium guajava, and Morus alba, were fed to two species of indigenous turacos, Knysna (Tauraco corythaix) and purple-crested (Gallirex porphyreolophus) turacos, and to invasive roseringed parakeets (Psittacula krameri). Seed retention time was determined as this can influence both seed dispersal and germination success. Germination success of ingested seeds was compared with that of manually de-pulped seeds, as well as to seeds in whole fruit. The germination success of seeds of all the invasive plant species increased significantly after ingestion by both turaco species compared with seeds from whole fruits. Germination success of manually de-pulped seeds did not differ significantly from that of turaco ingested seeds. In contrast, seed passage through the digestive tract of rose-ringed parakeets significantly reduced germination success and viability of ingested invasive plant species. Our results suggest that Knysna and purple-crested turacos are legitimate seed dispersers of fleshy-fruited invasive plants, while rose-ringed parakeets are mainly seed predators. Although seed predation by rose-ringed parakeets negatively affects the reproductive success of these plants, it is unlikely that this will suppress the spread of these invasive alien plants in South Africa as they are already well established. Furthermore, they can facilitate dispersal by seed regurgitation and dropping uneaten fruits away from the parent plant. Similar trends could be expected for indigenous seeds that rose-ringed parakeets feed on and therefore these birds remain a negative influence within invaded ecosystems.

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“…We obtained estimates of starling velocities by assuming straight-line movement between observation points; since observation points only rarely represented consecutive stops on a bird's route, these represent conservative underestimates. Gut passage rate data were collected from captive starlings that were fed bittersweet fruits (LaFleur 2006;LaFleur et al 2009). The mean passage rate of bittersweets seeds was min (SD), 43 ‫ע‬ 20 so we considered retention times ranging from 20 to 90 min (fig.…”

Section: Parameter Estimation For Starling-bittersweet Systemmentioning

confidence: 99%

“…European starlings (Sturnus vulgaris), which are particularly abundant frugivores in New England, are important seed dispersal agents for bittersweet. Large flocks of starlings forage heavily on the plentiful bittersweet fruits during the late autumn and winter months when other resources are scarce (LaFleur 2006) and increase germination of the seeds they ingest (LaFleur et al 2009). The first records of starlings in New England (New Haven, CT, 1906) predate those of bittersweet (Derby, CT, 1916), and their range expansion preceded that of bittersweet throughout New England ( fig.…”

Section: Introductionmentioning

confidence: 99%

Developing Dynamic Mechanistic Species Distribution Models: Predicting Bird-Mediated Spread of Invasive Plants across Northeastern North America

Merow

LaFleur

Silander

et al. 2011

The American Naturalist

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Species distribution models are a fundamental tool in ecology, conservation biology, and biogeography and typically identify potential species distributions using static phenomenological models. We demonstrate the importance of complementing these popular models with spatially explicit, dynamic mechanistic models that link potential and realized distributions. We develop general grid-based, pattern-oriented spread models incorporating three mechanisms--plant population growth, local dispersal, and long-distance dispersal--to predict broadscale spread patterns in heterogeneous landscapes. We use the model to examine the spread of the invasive Celastrus orbiculatus (Oriental bittersweet) by Sturnus vulgaris (European starling) across northeastern North America. We find excellent quantitative agreement with historical spread records over the last century that are critically linked to the geometry of heterogeneous landscapes and each of the explanatory mechanisms considered. Spread of bittersweet before 1960 was primarily driven by high growth rates in developed and agricultural landscapes, while subsequent spread was mediated by expansion into deciduous and coniferous forests. Large, continuous patches of coniferous forests may substantially impede invasion. The success of C. orbiculatus and its potential mutualism with S. vulgaris suggest troubling predictions for the spread of other invasive, fleshy-fruited plant species across northeastern North America.

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Does frugivory by European starlings (Sturnus vulgaris) facilitate germination in invasive plants?¹

Cited by 23 publications

References 40 publications

The potential for birds to disperse the seeds of Acacia cyclops, an invasive alien plant in South Africa

The potential for birds to disperse the seeds of Acacia cyclops, an invasive alien plant in South Africa

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

Developing Dynamic Mechanistic Species Distribution Models: Predicting Bird-Mediated Spread of Invasive Plants across Northeastern North America

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Does frugivory by European starlings (Sturnus vulgaris) facilitate germination in invasive plants?1

Cited by 23 publications

References 40 publications

The potential for birds to disperse the seeds of Acacia cyclops, an invasive alien plant in South Africa

The potential for birds to disperse the seeds of Acacia cyclops, an invasive alien plant in South Africa

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

Developing Dynamic Mechanistic Species Distribution Models: Predicting Bird-Mediated Spread of Invasive Plants across Northeastern North America

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Does frugivory by European starlings (Sturnus vulgaris) facilitate germination in invasive plants?¹