Search results for "Nesting"
showing 10 items of 87 documents
Indirect cues of nest predation risk and avian reproductive decisions
2009
Current life-history theory predicts that increased mortality at early stages of life leads to reduced initial investment (e.g. clutch size) but increased subsequent investment during the reproduction attempt. In a field experiment, migratory pied flycatchers Ficedula hypoleuca perceived differences in mammalian nest predation risk and altered their reproductive strategies in two respects. First, birds avoided nest sites manipulated to reflect the presence of a predator. Second, birds breeding in risky areas nested 4 days earlier and laid 10 per cent larger clutches than those in safe areas, a result that runs counter to the prevailing life-history paradigm. We suggest that the overwhelmin…
Nest Site Selection by Kentish Plover Suggests a Trade-Off between Nest-Crypsis and Predator Detection Strategies
2014
Predation is one of the main causes of adult mortality and breeding failure for ground-nesting birds. Micro-habitat structure around nests plays a critical role in minimizing predation risk. Plovers nest in sites with little vegetation cover to maximize the incubating adult visibility, but many studies suggest a trade-off between nest-crypsis and predator detection strategies. However, this trade-off has not been explored in detail because methods used so far do not allow estimating the visibility with regards to critical factors such as slope or plant permeability to vision. Here, we tested the hypothesis that Kentish plovers select exposed sites according to a predator detection strategy,…
Predation as a landscape effect: the trading off by prey species between predation risks and protection benefits.
2007
1. Predators impose costs on their prey but may also provide benefits such as protection against other (e.g. nest) predators. The optimal breeding location in relation to the distance from a nesting raptor varies so as to minimize the sum of costs of adult and nest predation. We provide a conceptual model to account for variation in the relative predation risks and derive qualitative predictions for how different prey species should respond to the distance from goshawk Accipiter gentilis nests. 2. We test the model predictions using a comprehensive collection of data from northern Finland and central Norway. First, we carried out a series of experiments with artificial bird nests to test if…
Trade-offs between sexual advertisement and immune function in the pied flycatcher (Ficedula hypoleuca).
2004
Good genes models of sexual selection assume that sexual advertisement is costly and thus the level of advertisement honestly reveals heritable viability. Recently it has been suggested that an important cost of sexual advertisement might be impairment of the functioning of the immune system. In this field experiment we investigated the possible trade-offs between immune function and sexual advertisement by manipulating both mating effort and activity of immune defence in male pied flycatchers. Mating effort was increased in a non-arbitrary manner by removing females from mated males during nest building. Widowed males sustained higher haematocrit levels than control males and showed higher…
Rapid change in host use of the common cuckoo Cuculus canorus linked to climate change
2010
Parasites require synchrony with their hosts so if host timing changes with climate change, some parasites may decline and eventually go extinct. Residents and short-distance migrant hosts of the brood parasitic common cuckoo, Cuculus canorus , have advanced their phenology in response to climate change more than long-distance migrants, including the cuckoo itself. Because different parts of Europe show different degrees of climate change, we predicted that use of residents or short-distance migrants as hosts should have declined in areas with greater increase in spring temperature. Comparing relative frequency of parasitism of the two host categories in 23 European countries before and af…
No synergy needed: ecological constraints favor the evolution of eusociality.
2015
In eusocial species, some individuals sacrifice their own reproduction for the benefit of others. It has been argued that the evolution of sterile helpers in eusocial insects requires synergistic efficiency gains through cooperation that are uncommon in cooperatively breeding vertebrates and that this precludes a universal ecological explanation of social systems with alloparental care. In contrast, using a model that incorporates realistic ecological mechanisms of population regulation, we show here that constraints on independent breeding (through nest-site limitation and dispersal mortality) eliminate any need for synergistic efficiency gains: sterile helpers may evolve even if they are …
New behavioural trait adopted or rejected by observing heterospecific tutor fitness
2010
Animals can acquire behaviours from others, including heterospecifics, but should be discriminating in when and whom to copy. Successful individuals should be preferred as tutors, while adopting traits of poorly performing individuals should be actively avoided. Thus far it is unknown if such adaptive strategies are involved when individuals copy other species. Furthermore, rejection of traits based on tutor characteristics (negative bias) has not been shown in any non-human animal. Here we test whether a choice between two new, neutral behavioural alternatives—breeding-sites with alternative geometric symbols—is affected by observing the choice and fitness of a heterospecific tutor. A fiel…
Optimal positioning of irregular shapes in stamping die strip
2010
The nesting of two-dimensional shapes is a common problem, where raw material has to be economically cut. As for the single-pass single-row strip layout, several algorithms, based on established methods, have been proposed. Moreover, it should be noticed that the optimum layout should also consider a few constraints, like grain orientation for subsequent forming operation, correct bridge width, and the commercial roll of metal width in order to make solutions applicable in real industrial environments. Most of the procedures until now shown in literature are quite complex and often ignore these real constraints. They usually make use of sliding techniques and are not able to effectively wor…
Is the Spanish coast within the regular nesting range of the Mediterranean loggerhead sea turtle (Caretta caretta)?
2008
We report the information on loggerhead sea turtle (Caretta caretta) nesting events which occurred on the Spanish Mediterranean coast in 2006. Two clutches of 78 and 82 eggs were discovered in the provinces of Valencia (eastern Spain) and Barcelona (north-eastern Spain). We discuss the increasing number of reports of sea turtle nests in Spain within the context of the nesting range of this species in the Mediterranean Sea.
Weather impacts on interactions between nesting birds, nest-dwelling ectoparasites and ants.
2022
AbstractWeather has a dominant impact on organisms, including their life histories and interspecific interactions. Yet, for nesting birds, and the arthropods inhabiting bird nests, the direct and cascading effects of weather are poorly known. We explored the influence of ambient temperatures and rainfall on the cohabitation of dome-shaped bird nests by Wood Warblers Phylloscopus sibilatrix, their blowfly Protocalliphora azurea ectoparasites, and predatory Myrmica and Lasius ants that may provide nest sanitation. We sampled blowflies and ants in 129 nests, and measured warbler nestlings during 2018–2020 in the primeval Białowieża Forest, eastern Poland. The probability of ectoparasites occur…