Topic
Hirundo
About: Hirundo is a research topic. Over the lifetime, 604 publications have been published within this topic receiving 15613 citations.
Papers published on a yearly basis
1 / 2
Papers
TL;DR: As a result of increased frequency of second broods determined by earlier arrival, the number of fledged offspring per season was larger after African winters with good in comparison to poor ecological conditions for barn swallows.
Abstract: We studied variation in arrival date to the breeding colonies in Italy of a trans-Saharan migratory bird, the barn swallow Hirundo rustica, in relation to variation in ecological conditions, as reflected by the normalized difference vegetation index (NDVI), in the winter quarters. Arrival date of old but not young individuals captured during consecutive breeding seasons was earlier after winters with favourable conditions. Change in arrival date in relation to change in NDVI was similar in the two sexes. Change in arrival date significantly and positively predicted change in breeding date. As a result of increased frequency of second broods determined by earlier arrival, the number of fledged offspring per season was larger after African winters with good in comparison to poor ecological conditions for barn swallows. This is the first study demonstrating phenotypic plasticity in migration phenology of a long-distance migratory bird in relation to ecological conditions during wintering.
297 citations
TL;DR: The asynchronous arrival pattern may leave some early-arriving swallows in a deteriorating breeding condition because the local food resource has to be divided between more individuals.
219 citations
TL;DR: In this article, a multiple target indicator and discriminator is provided for use on a tracking radar of the sequential lobe type, where the radar return signal has a phase modulated component at the scan rate frequency and also an additional second harmonic, amplitude modulation component at twice the rate frequency.
Abstract: A multiple target indicator and discriminator is provided for use on a tracking radar of the sequential lobe type. Multiple targets occurring within one radar beam-width cause the radar return signal to have a phase modulated component at the scan rate frequency and also an additional second harmonic, amplitude modulated component at twice the scan rate frequency. These modulated components are detected and removed from the radar return signal and used to provide a multiple target indicating signal. These modulated components are also used to produce an angle bias signal which, when added to an angle error signal in the radar angle track loop, causes the radar to track only one target in a formation of targets. Since the angle bias signal is developed directly from either the phase modulated component or the amplitude modulated component of the return signal produced by the multiple targets, such bias signal is responsive to any change in target reflectivity and thereby provides an adaptive angle bias signal.
208 citations
TL;DR: Colonies of cliff swallows appear to be information centers in which colony residents acquire information on the location of food sources and individuals often follow, and are followed by, their neighbors within the colony.
Abstract: Colonies of cliff swallows (Aves: Hirundo pyrrhonota) appear to be information centers in which colony residents acquire information on the location of food sources. Individuals that have been unsuccessful on a foraging trip return to the colony, locate a successful forager, and follow that individual to a food source. Individuals often follow, and are followed by, their neighbors within the colony, possibly because neighbors can observe foraging success through food brought back to nestlings. All individuals are equally likely to follow others or be followed, and thus all individuals benefit from opportunities to receive information.
170 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 24 |
| 2024 | 55 |
| 2023 | 37 |
| 2022 | 63 |
| 2021 | 20 |
| 2020 | 28 |