نتایج جستجو برای: visitation
تعداد نتایج: 2007 فیلتر نتایج به سال:
This paper evaluates early impacts of a home visiting program modeled after Healthy Families America on parenting behaviors in the first two years of life. It also proposes a framework for reconciling discrepant findings from randomized trials evaluating home visitation programs. A sample of 1173 families at risk for child abuse and neglect who met the criteria for Healthy Families New York (HF...
Pollination by animals is critical to sexual reproduction of most angiosperms. However, little is known about variation in pollination service to single plant species. We report results of a long-term study of Ipomopsis aggregata, a semelparous montane herb whose flowers are visited by hummingbird and insect pollinators as well as ‘‘floral larcenists.’’ We censused flower visitors over seven su...
Urbanisation typically results in a reduction of hollow-bearing trees and an increase in the density of particularly species, potentially resulting in an increased level of competition as cavity-nesting species compete for a limited resource. To improve understanding of hollow usage between urban cavity-nesting species in Australia, particularly parrots, we investigated how the hollow-using ass...
Bees, hoverflies and butterflies are taxa frequently studied as pollinators in agricultural and conservation contexts. Although there are many records of non-syrphid Diptera visiting flowers, they are generally not regarded as important pollinators. We use data from 30 pollen-transport networks and 71 pollinator-visitation networks to compare the importance of various flower-visiting taxa as po...
Free-ranging cervids acquire most of their essential minerals through forage consumption, though occasionally seek other sources to account for seasonal mineral deficiencies. Mineral sources occur as natural geological deposits (i.e., licks) or as anthropogenic mineral supplements. In both scenarios, these sources commonly serve as focal sites for visitation. We monitored 11 licks in Rocky Moun...
BACKGROUND AND AIMS This study examined the effect of plant traits and environmental factors on pollinator visitation in the winter-flowering Helleborus foetidus (Ranunculaceae) in three distant regions in the Iberian Peninsula. METHODS Geographical variation in floral visitor assemblage, plant traits and environmental factors were analysed during the flowering season. KEY RESULTS Differenc...
BACKGROUND AND AIMS Floral rewards may be associated with certain morphological floral traits and thus act as underlying factors promoting selection on these traits. This study investigates whether some traits that are under pollinator-mediated selection (flower number, stalk height, corolla diameter, corolla tube length and corolla tube width) in the Mediterranean herb E. mediohispanicum (Bras...
BACKGROUND Young children with sickle cell disease (SCD) are at risk for cognitive delay. In addition to biologic risk factors associated with SCD, environmental factors contribute to cognitive dysfunction within this cohort. METHODS We completed a single-arm, prospective cohort study. Children with SCD between the ages of 3 and 36 months and their caregivers were followed between October 201...
The component Allee effect has been defined as 'a positive relationship between any measure of individual fitness and the number or density of conspecifics'. Larger plant populations or large patches have shown a higher pollinator visitation rate, which may give rise to an Allee effect in reproduction of the plants. We experimentally tested the effect of number of conspecifics on reproduction a...
1. While many plant species offer rewards (e.g. nectar) to pollinators, some species, particularly in orchids, do not provide rewards. Ecological factors, such as interactions with rewarding co-flowering species may affect pollinator visitation rates to such deceptive species by influencing pollinator ability to learn to avoid deceptive plants (avoidance learning). 2. We tested the effect of fl...
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