Papers by Mercedes Molina-morales
Ecosistemas, Apr 26, 2024
Animal Behaviour, Sep 1, 2020
The sense of olfaction has been traditionally considered of low relevance in bird biology. In par... more The sense of olfaction has been traditionally considered of low relevance in bird biology. In particular, the location of cached seeds by scatter-hoarder corvids is assumed to depend on spatial memory, whereas no study has demonstrated the use of olfaction to detect these seeds. In this study we tested whether olfaction might play a role in the precise location of cached nuts by magpies, Pica pica, a scatter-hoarder corvid species. We conducted an experiment under natural conditions where nuts belonging to four treatments were buried, simulating natural caches, and we monitored the rate of nut detection by magpies. Three of the treatments included nuts with natural odour or odour of a strong-smelling substance (untreated nuts, nutshells filled with soil and nuts soaked in diesel), whereas the fourth treatment consisted of 3D-printed fake nuts made of polypropylene. The experiment was replicated in two sites and in several breeding territories, using a total of 624 nuts. Motion-activated cameras were installed to identify the animals foraging in the plots. The results show that magpies detected untreated nuts, nutshells or nuts soaked in diesel ca. three times more than 3D-printed fake nuts. Among detected and unburied nuts, the 3D-printed nuts were largely abandoned on site, followed by nutshells without a kernel, natural nuts and nuts soaked in diesel. All this strongly supports the hypothesis that magpies use olfaction to pinpoint cached nuts, either for nut recovery or pilfering, but once a nut is detected they may use other senses such as vision or touch for selection. Given the strong changes in landscape features that may occur under natural conditions between the time of nut caching and nut retrieval, we suggest that the use of olfaction might be crucial to help spatial memory in determining the location of cached nuts in corvids.
Ecosistemas, Apr 30, 2021
Behavioral Ecology, Jan 19, 2019
Great spotted cuckoos disregard information on conspecific breeding success while parasitizing ma... more Great spotted cuckoos disregard information on conspecific breeding success while parasitizing magpie hosts INSTRUCTIONS 1. Author groups: Please check that all names have been spelled correctly and appear in the correct order. Please also check that all initials are present. Please check that the author surnames (family name) have been correctly identified by a pink background. If this is incorrect, please identify the full surname of the relevant authors. Occasionally, the distinction between surnames and forenames can be ambiguous, and this is to ensure that the authors' full surnames and forenames are tagged correctly, for accurate indexing online. Please also check all author affiliations. as close as possible to their first citation. Please check that they are complete and that the correct figure legend is present. Figures in the proof are low resolution versions that will be replaced with high resolution versions when the journal is printed. These figures are currently intended to appear online in colour and black and white in print. Please check the black and white versions (these may be available at the end of the paper) and contact us if you have any concerns. Please re-word the legend/text to avoid using reference to colour. Alternatively, please let us know if you wish to pay for print colour reproduction or to have both versions in black and white. Please note that there is a £350/$600 charge for each figure reproduced in colour in print. Please check that all web addresses cited in the text, footnotes and reference list are up-to-date, and please provide a 'last accessed' date for each URL. Please provide a Funding statement, detailing any funding received. Remember that any funding used while completing this work should be highlighted in a separate Funding section. Please ensure that you use the full official name of the funding body, and if your paper has received funding from any institution, such as NIH, please inform us of the grant number to go into the funding section. We use the institution names to tag NIH-funded articles so they are deposited at PMC. If we already have this information, we will have tagged it and it will appear as coloured text in the funding paragraph. Please check the information is correct. [red text to be used for suppliers who are tagging the funding]
Revista catalana d'ornitologia = Catalan journal of ornithology, 2014
One of the major challenges of the coevolutionary theory is to understand the spatio-temporal dyn... more One of the major challenges of the coevolutionary theory is to understand the spatio-temporal dynamic of the infection processes and the evolution of defenses and counter-defenses between parasites and their hosts. A number of abiotic and biotic factors that can vary spatiotemporally may indirectly or directly affect the dynamic of the interaction. Avian brood parasites and their hosts provide an ideal system for the study of coevolution and in particular, the great spotted cuckoo (Clamator glandarius) and its main host in the Iberian Peninsula, the magpie (Pica pica), constitutes a suitable system for studying these issues. This system has provided strong support for an effect of brood parasitism on (1) the reproductive success of the host and ( ) on the evolution of host defensive mechanisms counteracting the negative effects of parasitism. However long-term studies with marked animals addressing issues related to patterns of host use by parasites, and defense mechanisms, are very scarce in general, and indeed nonexistent for this system. This thesis analyzes in a first block, through cross-sectional and longitudinal studies (based on resampling known individuals in different breeding seasons), the patterns of parasitism in the population. In a second block, through longitudinal studies, questions related to the evolution of defensive mechanisms against parasitism along the life of individual hosts are addressed. The results of this thesis suggest that the pattern of parasitism, at the population level, respond to a probabilistic process based on the spatialtemporal availability of magpie nests and the abundance of cuckoos in the population. In addition, it has been found that the population phenological mismatch between great spotted cuckoos and magpies changes between seasons depending on climatic factors, thus providing an additional explanation to the found annual variation in the probability of parasitism. Also, a longitudinal study reveals a pattern of structured parasitism at the individual level within the population. Indeed, females with a particular combination of traits (nest size, laying date and habitat characteristics) consistently escaped from cuckoo parasitism.
Biological Invasions, Dec 29, 2021
The monk parakeet (Myiopsitta monachus) has been introduced in the last decades to many cities in... more The monk parakeet (Myiopsitta monachus) has been introduced in the last decades to many cities in many parts of the world. For most of this time it has been restricted primarily to urban areas, but it is starting to spread to rural habitats. In its native range, the monk parakeet is considered a pest for agriculture, consuming a wide variety of crops such as grains, fruits, and vegetables. However, there is very little information about its potential role as a pest for agriculture in the areas where it is exotic. Here we conducted an experimental survey of the impact of the monk parakeet on corn in SE Spain using camera traps. The monk parakeet was the animal that produced the highest damage, being responsible for 98.6% of the time employed by all animals consuming corn. The percentage of cobs damaged ranged from 36.8 to 100% depending on the cultivar, whereas the crop loss (measured as the length of the cob consumed with respect to the total length of the cob) ranged from 17.7 to 71.1%. The results suggest that the monk parakeet may be a serious pest for agriculture in the Mediterranean basin if their populations continue growing.
Ecosistemas, Apr 27, 2017
Behavioral Ecology, 2016
Avian brood parasites leave parental care of their offspring to unrelated foster parents; therefo... more Avian brood parasites leave parental care of their offspring to unrelated foster parents; therefore, their fitness will closely relate to their efficiency in selecting the best host. Empirical studies have shown that parasitism is not random, although it is yet unclear if this results from strategic choices of better quality hosts by brood parasites or can be a consequence of hosts and/or nests characteristics that make them more exposed to parasitism. Here, we hypothesize that the optimal strategy of host use for a brood parasite may switch depending on fluctuations in the relative abundance of parasites with respect to hosts and predict that parasites should more likely select phenotypic traits indicating host quality when this is relatively low (i.e., many available host nests for each parasite at a given time). In an 8-year study of magpie Pica pica hosts parasitized by great spotted cuckoos Clamator glandarius, we have found that in years with lower than average parasitism bigger magpie nests were more likely parasitized than smaller ones, whereas in years with higher than average parasitism big and small magpie nests had a similar chance of being parasitized. Because nest size is a postmating sexually selected signal revealing parental abilities in magpies that can be used as a target to choose profitable hosts by cuckoos, our findings support the hypothesis that active selection will become a more prevalent great spotted cuckoo laying strategy when cuckoos have a larger availability of host nests to choose among.
INTED proceedings, Mar 1, 2022
Ecosistemas, Apr 30, 2019
Artículo publicado en Open Access bajo los términos de Creative Commons attribution Non Comercial... more Artículo publicado en Open Access bajo los términos de Creative Commons attribution Non Comercial License 3.0.
Journal of Ecology, Mar 29, 2021
For plants with seeds dispersed by scatter‐hoarders, decision‐making by animals when caching dete... more For plants with seeds dispersed by scatter‐hoarders, decision‐making by animals when caching determines the spatial pattern of seed dispersal and lays the initial template for recruitment, driving the regeneration of many plant species. However, the mechanism by which animal behaviour shapes seed distributions in spatially complex landscapes is not well understood. We investigated caching territoriality and site preferences to determine the spatial pattern of seed caching at different scales and whether scatter‐hoarding behaviour drives the spatial distribution of seedling emergence. We used radio‐tracking and automatic wildlife cameras to monitor holm oak (Quercus ilex) acorn caching by Eurasian magpies (Pica pica), who are effective scatter‐hoarders in agroforestry systems. We assessed the effect of caching territories, distance to seed source, habitat, sub‐habitat, microsites and caching material in the spatial pattern of acorn dispersal by magpies. In addition, we analysed the relationship between the density of cached acorns and of emerged seedlings in different habitats. Breeding magpies cached the acorns inside their caching territories, where they preferred tilled areas over oak plantations and mostly avoided old fields. These differences in habitat preference were maximized at relatively short to medium dispersal distances, where most acorns were cached, and decreased or disappeared at long distances. Within tree plantations, magpies preferred high plant‐productivity sites over low productivity ones. At the finest spatial scale, magpies preferred structures built by animals, such as rabbit grit mounds and latrines and ant litter mounds, to cache the acorns. In many sites, magpies selected uncommon materials such as stones and litter to cover caches. In the subsequent spring, seedling emergence was positively correlated with acorn cache density. Synthesis. Scatter‐hoarding is a hierarchical process in which caching sites are selected using different criteria at different spatial scales driven by territoriality and site preferences. Territoriality constrained dispersal distance and the habitats available for acorn caching. Magpie territoriality therefore indirectly drives oak seedling emergence and can determine oak recruitment and forest regeneration.
The American Naturalist, May 1, 2020
When the strength or nature of a host-parasite interaction changes over the host life cycle, the ... more When the strength or nature of a host-parasite interaction changes over the host life cycle, the consequences of parasitism can depend on host population age structure. Avian brood parasites reduce hosts’ breeding success, and host age may play a role in this interaction if younger hosts are more likely parasitized and/or less able to defend themselves. We analyzed whether the age of female magpie (Pica pica) hosts is associated with parasite attack or their ability to reject foreign eggs. We recorded parasitism and model egg rejection of known-age individuals over their lifetime and established whether the likelihood of parasitism or egg rejection changed with age or longevity. Parasitism probability did not change with female age, and there was a trend toward longer-lived females being less likely to be parasitized. However, model egg rejection probability increased with age for each individual female, and longer-lived females were more prone to reject model eggs. Most females in the population were young, and the majority of them accepted model eggs, suggesting that brood parasites exploiting younger host individuals are benefitting from a lower defense level of their hosts. Our results stress that the intensity of selection by brood parasites may be mediated by the age structure of host populations, a to-date neglected aspect in brood parasite–host research.
Evolutionary Ecology, Aug 15, 2022
Telomeres, DNA structures located at the end of eukaryotic chromosomes, shorten with each cellula... more Telomeres, DNA structures located at the end of eukaryotic chromosomes, shorten with each cellular cycle. The shortening rate is affected by factors associated with stress, and, thus telomere length has been used as a biomarker of ageing, disease, and different life history trade-offs. Telomere research has received much attention in the last decades, however there is still a wide variety of factors that may affect telomere measurements and to date no study has thoroughly evaluated the possible long-term effect of a storage medium on telomere measurements. In this study we evaluated the long-term effects of ethanol on relative telomere length (RTL) measured by qPCR, using blood samples of magpies collected over twelve years and stored in absolute ethanol at room temperature. We firstly tested whether storage time had an effect on RTL and secondly we modelled the effect of time of storage (from 1 to 12 years) in differences in RTL from DNA extracted twice in consecutive years from the same blood sample. We also tested whether individual amplification efficiencies were influenced by storage time, and whether this could affect our results. Our study provides evidence of an effect of storage time on telomere length measurements. Importantly, this effect shows a pattern of decreasing loss of telomere sequence with storage time that stops after approximate 4 years of storage, which suggests that telomeres may degrade in blood samples stored in ethanol. Our method to quantify the effect of storage time could be used to evaluate other storage buffers and methods. Our results highlight the need to evaluate the long-term effects of storage on telomere measurements, particularly in long-term studies.
Ecosistemas, Apr 30, 2021
Autores. Editado por la AEET. [Ecosistemas no se hace responsable del uso indebido de material su... more Autores. Editado por la AEET. [Ecosistemas no se hace responsable del uso indebido de material sujeto a derecho de autor]
Journal of Avian Biology, Oct 1, 2020
This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as
Behavioral Ecology, Aug 30, 2017
Avian brood parasites impose large fitness costs on their hosts and, thus, brood parasitism has s... more Avian brood parasites impose large fitness costs on their hosts and, thus, brood parasitism has selected for an array of host defensive mechanisms to avoid them. So far most studies have focused on antiparasite defenses operating at the egg and chick stages and neglected defenses that may work prior to parasite egg deposition. Here, we experimentally explore the possibility that hosts, as part of a front-line defense, might minimize parasitism costs through informed nest site choice based on perceived risk of cuckoo parasitism. We conducted a large-scale manipulation of visual and auditory cues potentially informing on the risk of great spotted cuckoo Clamator glandarius parasitism during the nest site choice period of the magpie Pica pica host to investigate its effect on host's nest settlement and individual year to year site fidelity. Early breeding magpies preferentially placed their nests in safe areas (i.e., in sites of low perceived risk of parasitism), and, this effect diluted with time elapsed since risk of parasitism was manipulated. Site fidelity of individual magpies decreased with risk of cuckoo parasitism, for those that were not parasitized in the previous year. Our results constitute the first strong evidence showing that hosts can minimize the costs of cuckoo parasitism through informed nest-site choice, calling for future consideration of defenses potentially operating prior to parasite egg deposition to achieve a better understanding of cuckoo-host coevolution.
Ecosistemas, Apr 29, 2023
Ecosistemas, Dec 16, 2017
Artículo publicado en Open Access bajo los términos de Creative Commons attribution Non Comercial... more Artículo publicado en Open Access bajo los términos de Creative Commons attribution Non Comercial License 3.0. MONOGRÁFICO: Papel de los estudios comportamentales en Ecología ecosistemas REVISTA CIENTÍFICA DE ECOLOGÍA Y MEDIO AMBIENTE
Journal of Ecology, Oct 26, 2022
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial ... more This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
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Papers by Mercedes Molina-morales