Carlos De La Cruz

Universidad de Extremadura | UNEX · Department of Anatomy, Cellular Biology and Zoology

Renesting is an important strategy employed by many bird species to compensate for nest failure. However, although replacement clutches may increase an individual's annual reproductive success, they impose substantial energetic and fitness costs. In some cooperatively breeding species, helpers lighten breeders' workloads thereby facilitating a seco...

The breeding period, a key stage in animal life histories, incurs high energy expenditure and there is often the possibility that parasite infections may compromise its success. Since defences against parasites are also costly to produce, individuals should optimise the allocation of limited available resources to reproduction activities or self-ma...

In many species of cooperative breeding birds, breeders and helpers participate in the parental care with different food provision rules. Normally, helpers feed nestlings less frequently and with smaller quantities of food than breeders. But studies analysing the reaction of feeders to nestling demand are scarce and rarely measure the quantity of f...

Carga parental en función del origen de los ayudantes de Rabilargo ibérico

La limpieza del nido es una parte importante en el éxito reproductor de aves, ya que minimiza el riesgo de infección por diferentes patógenos y evita en gran medida la depredación. En el caso del rabilargo ibérico (Cyanopica cooki), una especie de córvido con cría cooperativa, la retirada de los sacos fecales es llevada a cabo por los progenitores...

Estudio de la muda juvenil en el rabilargo ibérico.

La limpieza del nido es una parte importante en el éxito reproductor de aves, ya que minimiza el riesgo de infección por diferentes patógenos y evita en gran medida la depredación. En el caso del rabilargo ibérico (Cyanopica cooki), una especie de córvido con cría cooperativa, la retirada de los sacos fecales es llevada a cabo por los progenitores...

For cooperatively breeding birds, it has been proposed that breeders should reduce their investment in eggs when they count on helpers, because this can be compensated for by helpers provisioning of nestlings. Data from some species have supported this prediction, but this is not the case in others. It has also been proposed that mothers should not...

Individuals within animal groups may differ in personality and degree of familiarity raising the question of how this influences their social interactions. In Iberian magpies Cyanopica cooki, a portion of first-year males engage in cooperative behaviours and dispersal, allowing addressing this question. In this study, we first investigate the relat...

We identified and compared gross and microscopic lesions associated with the cestode, Parorchites zederi, in the digestive tracts of three species of penguins (Spheniscidae): the Chinstrap ( Pygoscelis antarctica ), Gentoo ( Pygoscelis papua ), and Adélie Penguins ( Pygoscelis adeliae ). The gastrointestinal tracts of 79 recently dead individuals (...

Stegophorus macronectes (Johnston & Mawson, 1942) is a gastrointestinal parasite found in Antarctic seabirds. The original description of the species, which was based only on females, is poor and fragmented with some unclear diagnostic characters. This study provides new morphometric and molecular data on this previously poorly described parasite....

Fitness can be profoundly influenced by the age at first reproduction (AFR), but to date the AFR-fitness relationship only has been investigated intraspecifically. Here we investigated the relationship between AFR and average lifetime reproductive success (LRS) across 34 bird species. We assessed differences in the deviation of the Optimal AFR (i.e...

Knowledge about parasites of Antarctic birds is fragmented and scarce. The aim of this work is to contribute to the knowledge of gastrointestinal parasites of the Chinstrap Penguin (Pygoscelis antarctica) from Deception Island (South Shetlands, Antarctica). Gastrointestinal tracts of 64 fresh dead individuals (61 chicks and three adults) were colle...

Knowledge about parasites of Antarctic birds is fragmented and scarce. The aim of this work is to contribute to the knowledge of gastrointestinal parasites of the Chinstrap Penguin (Pygoscelis antarctica) from Deception Island (South Shetlands, Antarctica). Gastrointestinal tracts of 64 fresh dead individuals (61 chicks and three adults) were colle...

Bonelli's eagle Aquila fasciata is in decline across the entire circum-mediterranean region, partly on account of habitat loss. Knowledge of territory characteristics is essential to developing effective conservation plans.We report on the extent and variability of territory size, and on the principal areas used, following radio monitoring of three...

We carried out a study to investigate the presence of some protozoan parasites (Cryptosporidium sp., Giardia sp., Toxoplasma gondii) on three species of Antarctic penguins: Adélie (Pygoscelis adeliae), gentoo (Pygoscelis papua) and chinstrap (Pygoscelis antarctica) from different locations along the Antarctic Peninsula and the South Shetland Island...

El Rabilargo ibérico es un pequeño córvido que se distribuye por el SW de la Península Ibérica, siendo la dehesa uno de sus hábitats típicos. Tradicionalmente se considera una especie perjudicial para la agricultura por los daños que ocasiona en algunos cultivos, sobre todo frutícolas. En este estudio se analizó el contenido de 107 estómagos de est...

In cooperatively breeding systems, breeders may reduce their provisioning to the brood when aided by helpers. However, this is found in only some species, and the reasons for the different reactions of breeders are far from clear. Recently, a paradoxical case of breeders in the azure-winged magpie, Cyanopica cyanus, increasing their contribution wh...

Animals may assess the quality of other individuals by using information that is contained in elaborate traits. We investigated the degree of sexual dimorphism in structural blue plumage coloration and the potential signal value of these traits in the azure-winged magpie Cyanopica cyanus. We predicted that in this species blue coloration should sig...

The function of colored ornaments is usually related to the signaling of individual quality in intra- and intersexual interactions. In cooperative breeding species, where only a fraction of the male population access the breeding status and the other fraction has the option to help breeding pairs, colored traits might provide the females with a rel...

Like all corvids, the Azure‐winged Magpie Cyanopica cyanus is sexually monomorphic in plumage, making it difficult to distinguish between males and females in the field. We examined sexual size dimorphism in a population of Iberian Azure‐winged Magpies C.c. cooki and used a discriminant function analysis based on five morphological characters to de...

In cooperatively breeding species, parents may be assisted by other individuals to feed the young. How breeding parents react when they receive help is poorly understood. Evidence suggests that parents usually maintain their feeding effort when starvation of chicks is common, and reduce it when other risks such as predation are more important for c...

In cooperatively breeding species, helpers may contribute to the success of the brood by increasing the number of independent offspring, but also, they may affect offspring condition and, hence, their survival and recruitment into the breeding population. This second type of benefits is rarely included in theoretical models or assessed in field stu...

Capsule: No case of parasitic interaction was found after 12 years of intensive monitoring of a marked population in Spain where both species are sympatric. Aims: To evaluate whether the Azure-winged Magpie is parasitized, and suggest possible causes that affect its relationship with the Great Spotted Cuckoo. Methods: Data from a long-term field st...

In this study, we investigated patterns of natural covariation between testosterone and reproductive status in a cooperatively breeding bird species, the azure-winged magpie (Cyanopica cyanus). To assess the relationship between testosterone and breeding behavior, we also manipulated testosterone (T) levels early in the season (before breeding star...

Abstract Helping to rear the offspring of others may be a way for younger birds to gain access to future reproduction especially when turnover of breeding opportunities is low. However, this explanation is not applicable to cases where adults also help, or when roles shift between helpers and breeders. Over a period of 6-yr, we studied a marked pop...

Timing plays a central role in the success of breeding activities, particularly in variable and unpredictable climates. In this paper we investigate the proximate factors influencing the timing of breeding behaviour in the azure-winged magpie (Cyanopica cyanus) in a Mediterranean environment. The azure-winged magpie is a social corvid, colonial bre...

Previous studies have suggested that the haematocrit could be related to a number of factors within the birds’ biological cycle. In this study, the variation found in the haematocrit of Azure-winged Magpies Cyanopica cyanus during the reproductive period is analysed and related to factors such as age, sex, reproductive status, moult, month and stud...

Successful multiple reproductive attempts in the same breeding season are extremely rare among the Corvidae, but are common in cooperatively-breeding species of similar size. The Azure-winged Magpie (Cyanopica cyanus) is a cooperatively-breeding corvid species for which there is so far no information from a marked population, to evaluate the presen...

Parasites often exert strong selection pressures on their hosts that have evolved anti-parasite defences to counter the negative effects of parasites. We studied the relationship between intensity of parasitism, one aspect of host immune response, and host reproductive success, using the house martin bug Oeciacushirundinis and its house martin Deli...

Postjuvenile moult in Azure‐winged Magpies Cyanopica cyanea cooki was studied in free‐living and captive birds. Most natal primary (99.7%) and secondary (81.2%) feathers were retained, but only 50% of rectrices. Estimates of individual moult duration in free living birds in the following feather tracts gave: 65 days for tertials, 13 days for greate...

A sexual dimorphism in the postjuvenile moult of the Azure‐winged Magpie Cyanopica cyanea cooki is described. Males retain significantly fewer primaries, secondaries, upper greater primary coverts and rectrices than females. This difference is interpreted as an adaption for mate selection and to improve reproductive success.

En la Laguna de Fuente Piedra (Málaga, España) se estudian las preferencias de las diferentes especies acuáticas para ubicar sus nidos, detectándose una competencia interespecífica por la ocupación del espigón central y espigones del NE, en especial referente al Flamenco común y Pagaza piconegra, que son además las especies más numerosas. Igualment...

RESUMEN.—Variación del hematocrito durante el periodo reproductor en el Rabilargo Cyanopica cyanus. Algunos estudios previos han sugerido que el hematocrito podría estar relacionado con diversos factores del ciclo biológico de las aves. En este trabajo se analizan las variaciones del hematocrito encontradas en el Ra- bilargo Cyanopica cyanusdurante...