Age-dependent relationships between multiple sexual pigments and condition in males and females

The reliability of sexual signaling may change across age classes due to shifts in resource allocation patterns. Two contrasting hypotheses exist regarding how the condition dependence of ornaments may shift with age, and both have received empirical support. On one hand, ornaments may more reliably reflect condition and quality in older individuals, because younger individuals of high quality invest in survival over signaling effort. On the other hand, the condition dependence of ornaments may decline with age, if older individuals in poor condition terminally invest in ornaments, or if resource constraints decline with age. Further, the expression and condition dependence of different ornaments may shift with age in unique ways, such that multifaceted sexual displays maintain reliable signaling across age classes. In yellow warblers (Setophaga petechia) of both sexes, we assessed how relationships between carotenoid-and phaeomelanin-based sexual pigmentation, prenesting body reserves, and condition at molt (reflected by growth bars and feather quality) vary across age classes. Melanin coverage correlated with condition at molt across age classes in males and showed high repeatability in both sexes. In contrast, carotenoid saturation increased longitudinally with age in males and correlated with condition at molt in different age classes in the 2 sexes. Specifically, carotenoid saturation correlated positively with condition at molt in younger, but not older males, whereas in females, the situation was reversed, with a positive correlation present only in older females. Results suggest that age-dependent signaling may promote maintenance of multifaceted sexual displays and that agedependent signaling dynamics depend on sex. © The Author 2013. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved

Evaluating Conservation Flagships and Flagship Fleets

Flagship species are widely used in conservation but this single species approach has attracted criticism. One response is the “flagship fleet,” which uses several flagship species in one conservation marketing campaign. However, marketing theory suggests multibrand campaigns can be counter-productive. Here, we develop an evaluation strategy for conservation flagships, and use it to: measure the effectiveness of an existing bird flagship species; detect whether additional species are needed; and, if appropriate, identify which species should be added to create a flagship fleet. We show the bird species has high levels of visibility and recognition, but has traits that appeal to only half the target audience. We also show that this shortcoming could be overcome by forming a flagship fleet based on adding an endemic mammal or fish species but there are additional strategic considerations that must be taken into account, namely in terms of costs and potential future conflicts

An Assessment of the Impact of Hafting on Paleoindian Point Variability

It has long been argued that the form of North American Paleoindian points was affected by hafting. According to this hypothesis, hafting constrained point bases such that they are less variable than point blades. The results of several studies have been claimed to be consistent with this hypothesis. However, there are reasons to be skeptical of these results. None of the studies employed statistical tests, and all of them focused on points recovered from kill and camp sites, which makes it difficult to be certain that the differences in variability are the result of hafting rather than a consequence of resharpening. Here, we report a study in which we tested the predictions of the hafting hypothesis by statistically comparing the variability of different parts of Clovis points. We controlled for the potentially confounding effects of resharpening by analyzing largely unused points from caches as well as points from kill and camp sites. The results of our analyses were not consistent with the predictions of the hypothesis. We found that several blade characters and point thickness were no more variable than the base characters. Our results indicate that the hafting hypothesis does not hold for Clovis points and indicate that there is a need to test its applicability in relation to post-Clovis Paleoindian points

A Morphometric Assessment of the Intended Function of Cached Clovis Points

A number of functions have been proposed for cached Clovis points. The least complicated hypothesis is that they were intended to arm hunting weapons. It has also been argued that they were produced for use in rituals or in connection with costly signaling displays. Lastly, it has been suggested that some cached Clovis points may have been used as saws. Here we report a study in which we morphometrically compared Clovis points from caches with Clovis points recovered from kill and camp sites to test two predictions of the hypothesis that cached Clovis points were intended to arm hunting weapons: 1) cached points should be the same shape as, but generally larger than, points from kill/camp sites, and 2) cached points and points from kill/camp sites should follow the same allometric trajectory. The results of the analyses are consistent with both predictions and therefore support the hypothesis. A follow-up review of the fit between the results of the analyses and the predictions of the other hypotheses indicates that the analyses support only the hunting equipment hypothesis. We conclude from this that cached Clovis points were likely produced with the intention of using them to arm hunting weapons

Unexpected diversity in socially synchronized rhythms of shorebirds

The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators. Individuals can temporally segregate their daily activities (for example, prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (for example, group foraging, communal defence, pairs reproducing or caring for offspring). The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood. Here we investigate these rhythms in the context of biparental care, a particularly sensitive phase of social synchronization where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within-and between-species diversity in incubation rhythms. Between species, the median length of one parent's incubation bout varied from 1-19 h, whereas period length-the time in which a parent's probability to incubate cycles once between its highest and lowest value-varied from 6-43 h. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or who actively protect their nest against predators. Rhythms entrainable to the 24-h light-dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms.</p

Blood Parasites in Owls with Conservation Implications for the Spotted Owl (Strix occidentalis)

The three subspecies of Spotted Owl (Northern, Strix occidentalis caurina; California, S. o. occidentalis; and Mexican, S. o. lucida) are all threatened by habitat loss and range expansion of the Barred Owl (S. varia). An unaddressed threat is whether Barred Owls could be a source of novel strains of disease such as avian malaria (Plasmodium spp.) or other blood parasites potentially harmful for Spotted Owls. Although Barred Owls commonly harbor Plasmodium infections, these parasites have not been documented in the Spotted Owl. We screened 111 Spotted Owls, 44 Barred Owls, and 387 owls of nine other species for haemosporidian parasites (Leucocytozoon, Plasmodium, and Haemoproteus spp.). California Spotted Owls had the greatest number of simultaneous multi-species infections (44%). Additionally, sequencing results revealed that the Northern and California Spotted Owl subspecies together had the highest number of Leucocytozoon parasite lineages (n = 17) and unique lineages (n = 12). This high level of sequence diversity is significant because only one Leucocytozoon species (L. danilewskyi) has been accepted as valid among all owls, suggesting that L. danilewskyi is a cryptic species. Furthermore, a Plasmodium parasite was documented in a Northern Spotted Owl for the first time. West Coast Barred Owls had a lower prevalence of infection (15%) when compared to sympatric Spotted Owls (S. o. caurina 52%, S. o. occidentalis 79%) and Barred Owls from the historic range (61%). Consequently, Barred Owls on the West Coast may have a competitive advantage over the potentially immune compromised Spotted Owls

Unexpected diversity in socially synchronized rhythms of shorebirds

The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment1, 2, 3, 4. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions1, 5, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators6, 7, 8, 9, 10. Individuals can temporally segregate their daily activities (for example, prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (for example, group foraging, communal defence, pairs reproducing or caring for offspring)6, 7, 8, 9, 11. The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood5, 6, 7, 9. Here we investigate these rhythms in the context of biparental care, a particularly sensitive phase of social synchronization12 where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within- and between-species diversity in incubation rhythms. Between species, the median length of one parent’s incubation bout varied from 1–19 h, whereas period length—the time in which a parent’s probability to incubate cycles once between its highest and lowest value—varied from 6–43 h. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or who actively protect their nest against predators. Rhythms entrainable to the 24-h light–dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity5, 6, 7, 9. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms

Do female zebra finches (Taeniopygia guttata) copy each other\u27s mate preferences?

We investigated whether female zebra finches (Taeniopygia guttata) would alter their mate preferences after observing the choices of other females. Experimental trials consisted of four 30-min stages: (A) acclimation, (B) observer female chooses between two males, (C) observer female watches a model female interact with her nonpreferred male from stage B, and (D) observer female again chooses between the two males. Control trials were identical except that there was no model female in stage C. Females in both experimental and control trials spent significantly more time with the nonpreferred male in stage D than they had in stage B; thus, our experiment appeared to reveal no evidence of mate choice copying. There was, however, a significant positive relationship between the increase in the time that an observer female in experimental trials spent with her nonpreferred male in stage D and the number of interactions that she had previously observed between the model female and that male in stage C. A second..., Le but de notre recherche est d\u27examiner si les femelles du diamant mandarin (Taeniopygia guttata) modifient leur choix de parternaire en fonction de celui d\u27autres femelles. La procédure expérimentale consiste en quatre étapes de 30 min : (A) période d\u27acclimatation, (B) une femelle observatrice choisit entre deux mâles, (C) cette même femelle observe une femelle modèle en interaction avec le mâle non choisi de l\u27étape B et (D) la femelle observatrice choisit à nouveau entre les deux mâles. Les procédures témoins sont semblables, sauf qu\u27il n\u27y a pas de femelle modèle présente à l\u27étape C. Les femelles expérimentales et témoins ont toutes deux passé significativement plus de temps avec le mâle non retenu à l\u27étape D qu\u27à l\u27étape B. Notre expérience ne semble donc pas démontrer clairement que le choix de partenaire chez le diamant mandarin se fait en imitant le choix d\u27autres femelles. Cependant, il y a une relation positive significative entre l\u27augmentation du temps que les femelles observatrices passen..