Tomas Redondo | Estación Biológica de Doñana (EBD-CSIC) (original) (raw)

Books by Tomas Redondo

Papers by Tomas Redondo

The Quarterly Review of Biology, Dec 1, 1994

Evolutionary ecology, Apr 23, 2024

Fernandez-Duque et al. (Evol Ecol 37:859-869, 2023) reported instances where fledglings, able to ... more Fernandez-Duque et al. (Evol Ecol 37:859-869, 2023) reported instances where fledglings, able to move freely, were found in the nests of others of the same species containing chicks that were too young to fly. Interestingly, the foster parents fed these intruder fledglings. The researchers identified this as a novel behavior and termed it "Nest Integration." However, this behavior had been documented previously as "nest switching" in both ornithological and behavioral literature. By integrating the findings of Fernandez-Duque et al. with the literature on nest switching, the evolution of nest switching highlighted by them, and the conditions that might promote it, could be better understood.

Journal of Ornithology

Physiological and Biochemical Zoology, 2019

Hematological profiles are routinely used to assess the health status of animals. Several methods... more Hematological profiles are routinely used to assess the health status of animals. Several methods have been developed for blood cell counting, but they are typically expensive and/or time-consuming. Here, we present a free image-processing software, Mizutama, developed for counting cells in photographs of blood smears. Mizutama uses the thresholding method to transform original photographs into grayscale trinary images. Following a number of parameters, Mizutama searches in the image for cells of a given size, with a nucleus size relative to cytoplasm surface area. The software is not only easy, versatile, and intuitive to handle but also fast when counting cells in photographs. Moreover, we show that it is highly accurate, failing to detect only ca. 1.4% of avian red cells in ordinary microscopic photographs. The Mizutama application may greatly facilitate the counting of erythrocytes and other blood cells in physiological studies, saving time and money.

Some theoretical models predict that nestling begging must be a costly activity to transmit relia... more Some theoretical models predict that nestling begging must be a costly activity to transmit reliable information to parents about offspring hunger. One candidate cost is oxidative stress, which could impair growth or immune function. This hypothesis predicts that nestlings in a poor oxidative status should pay higher costs for a given amount of begging, hence beg at lower rates for a similar degree of hunger. To test this prediction, we experimentally induced a transient alteration of the oxidative status of Barn Swallow (Hirundo rustica) nestlings by administering them either a single dose of a pro-oxidant substance (BSO) or an antioxidant (vitamin E), and recorded their begging behaviour. Chicks treated with vitamin E increased their begging rates in the hours following treatment. However, and contrary to prediction, BSO nestlings did not decrease begging compared to controls. These inconsistent results are difficult to explain by the hypothesis that begging performance is mediated by the oxidative status of nestlings because chicks with an impaired oxidative status (the BSO group) begged the same as controls. Alternatively, vitamin E may alleviate the inhibitory effects on begging of stress responses mediated by glucocorticoids. This study suggests that oxidative costs of begging are minor or absent in this species. Future studies should consider alternative explanations for an association between oxidative status, antioxidant supplementation and begging behaviour, particularly those involving glucocorticoids. Keywords Begging • Honest signalling • Oxidative stress • Hirundo rustica • Vitamin E • BSO • Glucocorticoids Zusammenfassung Entstehen den Nestlingen von Rauchschwalben durch Betteln oxidative Kosten? Es gibt theoretische Modelle, die besagen, dass das Betteln von Nestlingen vermutlich eine kostenintensive Art ist, um den Eltern zuverlässige Information über den Hunger der Jungen zu geben. Ein möglicher Kostenfaktor wäre oxidativer Stress, der das Wachstum oder das Immunsystem beeinträchtigen könnte. Diese Hypothese besagt, dass Nestlingen in einem schlechten oxidativen Zustand höhere Kosten für ein bestimmtes Maß an Betteln entstehen und sie deshalb bei gleichem Hunger besser weniger häufig betteln sollten. Um dies zu testen, führten wir experimentell eine vorübergehende Veränderung des Oxidationsstatus von Nestlingen der Rauchschwalbe (Hirundo rustica) herbei, indem wir ihnen entweder eine einmalige Dosis einer pro-oxidativen Substanz (BSO) oder eines Antioxidans (Vitamin E) verabreichten und ihr Bettelverhalten aufzeichneten. Die mit Vitamin E behandelten Küken bettelten in den Stunden nach der Behandlung häufiger. Aber entgegen der Vorhersage bettelten die BSO-Küken im Vergleich zu den Kontrollen nicht weniger. Diese widersprüchlichen Ergebnisse Communicated by I. Moore.

Behavioral Ecology

Parent–offspring conflict over food allocation can be modeled using two theoretical frameworks: p... more Parent–offspring conflict over food allocation can be modeled using two theoretical frameworks: passive (scramble competition) and active choice (signaling) resolution models. However, differentiating between these models empirically can be challenging. One possibility involves investigating details of decision-making by feeding parents. Different nestling traits, related to competitive prowess or signaling cryptic condition, may interact additively or non-additively as predictors of parental feeding responses. To explore this, we experimentally created even-sized, small broods of pied flycatchers and manipulated nestling cryptic quality, independently of size, by vitamin E supplementation. We explored how interactions between nestling cryptic condition, size, signals, and spatial location predicted food allocation and prey-testing by parents. Parents created the potential for spatial scramble competition between nestlings by feeding from and to a narrow range of nest locations. Hea...

Altricial nestlings in structured families show a diverse array of behavioural mechanisms to comp... more Altricial nestlings in structured families show a diverse array of behavioural mechanisms to compete for food, ranging from signalling scrambles to aggressive interference. Rates of filial infanticide are moderately high in white storks. It has been hypothesized that this unusual behaviour is an adaptive parental response to the absence of efficient mechanisms of brood reduction (aggression or direct physical interference) by nestlings. To test this latter assumption, we analyzed video recordings of 41 complete feeding episodes at 32 broods during the first half of the nestling period, when nestlings complete 90% of growth and chick mortality and size asymmetries are highest. Parents delivered food to all nestlings simultaneously by regurgitating on the nest floor. No direct (bill to bill) feeding was recorded. Senior nestlings were never observed to limit their junior nestlings from eating food, either by aggression or physical interference. Experimental feeding tests revealed that heavier nestlings handled prey items more efficiently and ate food at a higher speed. The high degree of tolerance shown by senior nestlings is unusual among birds with similar ecological and phylogenetic affinities, such as herons. Tolerance by seniors cannot be easily explained by absence of parental favouritism or proximate factors known to affect the occurrence of sibling aggression in other species (rate of food transfer, brood size, hatching asynchrony or length of nestling period)

Este es un libro (primero publicado por autores de lengua española) que trata sobre las estrategi... more Este es un libro (primero publicado por autores de lengua española) que trata sobre las estrategias que los seres vivos emplean para maximizar su eficacia biológica, abordadas desde los cuatro enfoques clásicos que constituyen la esencia de la Etología: las causas inmediatas o mecanismos, la ontogenia, la filogenia y la función adaptativa

Trends in Ecology & Evolution, 1999

Journal of Ornithology, 1991

Ethology, 2010

Like most corvids, adult magpies (Pica pica) have harsh vocal repertoires characterized by a wide... more Like most corvids, adult magpies (Pica pica) have harsh vocal repertoires characterized by a wide distribution of energy over the frequency scale. Shortly after hatching, begging calls of magpie nestlings have a tonal quality hut become increasingly noisier as they develop. T h e appearance of harsh structures in the calls is closely related to a process of frequency modulation which ends at about 16-18 days. At this age, nestlings suddenly develop genuine harsh calls. typical of fledglings and adult birds. During development, similarities can he ohserved between frequency modulation and noise production, suggesting that nestlings acquire the ability to produce adult harsh vocalizationc by modulating their begging calls. This hypothesis does not explain, however, why genuine harsh calls develop without transitional forms being evident in the preceding begging calls. Also, intra-and intcrspecitic differences in modulation rates d o not cause differences in noise production in the way that this hypothesis would at first suggest. Frequency modulation and noise production d o not seem to be involved in the ontogeny of the adult voice. It is suggested that both features contribute to call degradation in the environment, in order to compensate for the increasing risks of nests being detected by predators due to the more detectable calls of older nestlings.

Behavioral Ecology, 2001

We investigated whether an increase in begging levels delays growth of chicks. In experiment 1, w... more We investigated whether an increase in begging levels delays growth of chicks. In experiment 1, we hand-reared nine pairs of ring dove squabs, divided into a control and a begging group. All squabs received similar amounts of food, but those in the begging group had to beg for a prolonged period in order to be fed, while squabs in the control group received food without begging. Squabs stopped responding to the treatment after 10 days and, at that time, there was no effect of induced begging on their body mass. In experiment 2, we hand-reared 27 pairs of magpie chicks for 3 days. The design of experiment 2 was similar to that of experiment 1. Daily food intake and begging affected growth rates. On average, chicks in the begging group grew 0.8 g/day less than control chicks, which represents a decrease of 8.15% in growth rate. Because growth is usually positively associated with expected fitness, this demonstrates that begging is a costly behavior, an assumption routinely made in models of begging behavior.

Animal Behaviour, 1990

The mating behaviour of red deer stags, Cervus elaphus, has been extensively described as harem d... more The mating behaviour of red deer stags, Cervus elaphus, has been extensively described as harem defence. However, it appears that territoriality may be chosen as a mating strategy when certain conditions are met. In a study area in southwestern Spain, early on in the rut, about 58% of adult males established territories in preferred areas, defended the territory against other males even in the absence of females, and courted females only within territorial boundaries. The mean territory size was about 2.3 ha. The later a male settled on his territory during the rut the fewer the females he was able to keep. The preferred areas where males established territories were also extensively used by females even before the start of the rut. The number of females per ha before the onset of the rut was positively correlated with the cumulative number of hinds that each male kept later on. Hence the reproductive success of males was largely influenced by the location of their territory. Such intensive use by females of a highly productive area for feeding and daily passage in an otherwise low-resource environment appears to promote the defence of territories located in the richest area. This paper provides the first evidence for territorial defence of mates in red deer and may contribute to the understanding of the dynamic nature of mating behaviour in ungulates.

Behavioral Ecology, 2002

The offspring of birds and mammals use a combination of movements and vocalizations, known as beg... more The offspring of birds and mammals use a combination of movements and vocalizations, known as begging, to solicit food from their parents. A widespread interpretation of begging is that it constitutes an honest signal of offspring need. But we know that in the house sparrow (Passer domesticus) the intensity of begging calls reflects the past experience of offspring in addition to their need. Here we show that this result generalizes to other species. An experiment with hand-reared magpies (Pica pica) and great spotted cuckoos (Clamator glandarius) indicates that the begging strategies depend on the past experience of chicks and the composition of their brood. In asynchronous two-magpie broods, both chicks begged at the same intensity when the large chick obtained food more easily than its sibling, but the large chick begged at higher intensity when it was easier for the smaller chick to obtain food. Cuckoo chicks begged at higher intensity than magpies.

Abstract. White stork, Ciconia ciconia, chicks were observed to abandon their natal nests prior t... more Abstract. White stork, Ciconia ciconia, chicks were observed to abandon their natal nests prior to independence and to be adopted by neighbouring foster parents in approximately 40 % of broods at three breeding colonies. Nest switching coincided with a decrease in feeding rates by parents and an increase in aggression by siblings triggered by the flight exercises of nestmates, and mainly aVected the eldest chicks in larger broods. Chicks that abandoned their natal nests moved into broods containing both fewer and younger chicks, and thus experienced a decrease in aggression rate compared with their natal broods. Adopted chicks may also have increased their food intake as a consequence of nest switching. Resident chicks suVered from lower feeding rates during adoption and had lower mass increments than chicks in non-fostering broods of comparable age and size. Both adults and chicks were highly aggressive against trespassing chicks. The probability of aggression was a good predictor ...

Datasets as supporting information to article "Vitamin E supplementation –but not induced ox... more Datasets as supporting information to article "Vitamin E supplementation –but not induced oxidative stress- influences telomere dynamics during early development" to be published in Frontiers in Ecology and Evolution. The Readme files describe variables in the corresponding dataset.