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Age classes of the males paired with females from five age classes of northern flickers. Sample sizes of females are above the bars. Data include all breeding pairs from 1997–2014 at Riske Creek, British Columbia
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Age-related improvement in reproductive performance is widespread in vertebrates and constraints at young ages are a common cause. The sex that invests energetically more in reproduction, typically the female, is predicted to show stronger age-related performance but the effect of the male’s age on reproduction has often been ignored. I studied age...
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The breeding ecology of high-altitude birds in the Himalaya and the Hengduan Mountains remains poorly known. The present study describes the breeding biology of the Fire-tailed Sunbird Aethopyga ignicauda in southwestern China. Fieldwork was conducted at a high- altitude mountain pass in the Gaoligong Mountains from March to July 2014. Based on 20...
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... However, since visitation rates increase with brood age , we also ran the models separately using the rates on Day 7 and Day 11 to ensure results were consistent. We also added the ages of the mother and father (Wiebe 2018), and hatch date (days after 1 April) as fixed effects to control for their effects on fitness outcomes. Since breeding success usually correlates with peak food abundance (Lack 1968, Cresswell andMccleery 2003), we added a quadratic fixedeffect term for hatch date, assuming peak food abundance in the middle of the breeding season. ...
Measuring parental care behaviour in the wild is central to the study of animal ecology and evolution, but it is often labour‐ and time‐intensive. Efficient open‐source tools have recently emerged that allow animal behaviour to be quantified from videos using machine learning and computer vision techniques, but there is limited appraisal of how these tools perform compared to traditional methods. To gain insight into how different methods perform in extracting data from videos taken in the field, we compared estimates of the parental provisioning rate of wild house sparrows Passer domesticus from video recordings. We compared four methods: manual annotation by experts, crowd‐sourcing, automatic detection based on the open‐source software DeepMeerkat, and a hybrid annotation method. We found that the data collected by the automatic method correlated with expert annotation (r = 0.62) and further show that these data are biologically meaningful as they predict brood survival. However, the automatic method produced largely biased estimates due to the detection of non‐visitation events, while the crowd‐sourcing and hybrid annotation produced estimates that are equivalent to expert annotation. The hybrid annotation method takes approximately 20% of annotation time compared to manual annotation, making it a more cost‐effective way to collect data from videos. We provide a successful case study of how different approaches can be adopted and evaluated with a pre‐existing dataset, to make informed decisions on the best way to process video datasets. If pre‐existing frameworks produce biased estimates, we encourage researchers to adopt a hybrid approach of first using machine learning frameworks to preprocess videos, and then to do manual annotation to save annotation time. As open‐source machine learning tools are becoming more accessible, we encourage biologists to make use of these tools to cut annotation time but still get equally accurate results without the need to develop novel algorithms from scratch.
... Paternal age in humans was shown to be the predominant factor determining the number of de novo mutations occurring within children (Kong et al. 2012), and increased paternal age in the houbara bustard, Chlamydotis undulata, was found to decrease sperm quality and hatching success and to slow neonatal development (Preston et al. 2015). Conversely, male age in a different bird species, Colaptes auratus, was associated with increased clutch size, earlier laying, and greater fledging success (Wiebe 2018). Results from the present study appear to support the notion that no clear patterns of directional effects exist across animal species. ...
Parental age at reproduction influences offspring size and survival by affecting prenatal and postnatal conditions in a wide variety of species, including humans. However, most investigations into this manifestation of ageing focus upon maternal age effects; the effects of paternal age and interactions between maternal and paternal age are often neglected. Furthermore, even when maternal age effects are studied, pre- and post-natal effects are often confounded. Using a cross-fostered experimental design, we investigated the joint effects of pre-natal paternal and maternal and post-natal maternal ages on five traits related to offspring outcomes in a laboratory population of a species of burying beetle, Nicrophorus vespilloides. We found a significant positive effect of the age of the egg producer on larval survival to dispersal. We found more statistical evidence for interaction effects, which acted on larval survival and egg length. Both interaction effects were negative and involved the age of the egg-producer, indicating that age-related pre-natal maternal improvements were mitigated by increasing age in fathers and foster mothers. These results agree with an early study that found little evidence for maternal senescence, but it emphasizes that parental age interactions may be an important contributor to ageing patterns. We discuss how the peculiar life history of this species may promote selection to resist the evolution of parental age effects, and how this might have influenced our ability to detect senescence.
... Male woodpeckers are unusual because they invest more than females in nest-building, incubation of eggs, and brooding of young (Wiebe 2005(Wiebe , 2008 but both sexes coordinate incubation and provisioning (Wiebe 2010) which may explain the high reproductive success when breeding with a familiar partner. Productivity within a population of Northern Flickers (Colaptes auratus) in central British Columbia improved with age of the parents but there were additional benefits of having a familiar partner when age was controlled for (Wiebe 2018). In particular, initiation of egg-laying in spring was faster for retained pairs than for new partnerships so one would predict that divorce rate should be low. ...
... Whatever the proximate cause, divorce did not provide subsequent benefits for Northern Flickers as only about 1/4 of divorced males and females secured a mate of an older age class in the subsequent year, and the rate of improvement in reproductive output between subsequent breeding attempts was not higher relative to retained or widowed pairs. Annual mortality rates are high so ~39% of breeding Northern Flickers annually are yearlings (Wiebe 2018), which means the pool of previously unpaired individuals in spring is mostly yearlings, and so the chance of improving one's performance by securing an older and more experienced partner may be small. Because the reproductive output of divorced birds did not differ in any measure from that of widowed birds, in flickers, there is a high reproductive cost of finding a new mate per se. ...
Divorce is widespread among species of birds and may either be an adaptive strategy to secure a better mate or territory or be a nonadaptive result of a failure to maintain the pairbond. I examined the causes and consequences for divorce in the Northern Flicker (Colaptes auratus), a migratory woodpecker with a high annual mortality rate. In a long-term population study of 1,793 breeding pairs over 17 years, the within-season divorce rate was 4.6% and the between-season divorce rate was 15.5%. Retained pairs within a season initiated their renest 5 days faster than divorced birds that had no greater fledgling production, suggesting that within-season divorce was making the best of a bad job with severe time constraints. Poor performance in the year prior to divorce was not strongly associated with divorce, and analysis of multiple breeding stages revealed that divorcing individuals in the subsequent year had later laying dates, smaller clutches, and fewer fledglings than retained pairs but no better performance than widowed individuals. Analyzing the data separately by sex showed that neither males nor females benefitted from divorce. Thus, there is a reproductive cost linked to finding a new partner per se, but no reproductive advantage associated with divorce. New mates after divorce were usually not older (not higher quality) than previous mates, so intrasexual competition was probably not driving partnership splits. The most plausible explanation seems to be a “bet-hedging” hypothesis in which birds re-pair rapidly in spring if their previous mate does not quickly arrive during spring migration. Divorce in Northern Flickers does not appear to be adaptive and future studies on arrival and interactions of individuals in spring will elucidate proximate constraints on relocating the previous partner.
... Paternal age in humans was shown to be the predominant 393 factor behind the exponential increase in the number of de novo mutations occurring within 394 children(Kong et al. 2012), and increased paternal age in the houbara bustard, Chlamydotis undulata, was found to decrease sperm quality and hatching success and to slow neonatal 396 development(Preston et al. 2015). Conversely, male age in a different bird species, Colaptes 397 auratus, was associated with increased clutch size, earlier laying and greater fledging success 398(Wiebe 2018). Results from the present study appear to support the notion that no clear 399 patterns of directional effects exist. ...
Parental age at reproduction influences offspring size and survival by affecting prenatal and postnatal conditions in a wide variety of species, including humans. However, most investigations into this manifestation of ageing focus upon maternal age effects; the effects of paternal age and interactions between maternal and paternal age are often neglected. Furthermore, even when maternal age effects are studied, pre-and postnatal effects are confounded. Using a cross-fostered experimental design, we investigated the joint effects of paternal and pre-and postnatal maternal ages on numerous offspring outcomes in a laboratory population of a species of burying beetle, Nicrophorus vespilloides. When we correct our tests for significance for multiple comparisons, we found no clear evidence for any parental effect senescence acting on egg size, larval weight, or larval survival. Nor did we find a statistical effect of paternal or egg producer age on the outcomes of foster mothers as measured by weight change experienced during caregiving. These findings are consistent with recent negative results reported in a similar study of N. vespilloides maternal age effects while also expanding these to other offspring traits and to paternal age effects. We discuss how the peculiar life history of this species may promote selection to resist the evolution of parental age effects, and how this might have influenced our ability to detect senescence.
Avian hatching failure is a widespread phenomenon, affecting around 10% of all eggs that are laid and not lost to predation, damage, or desertion. Our understanding of hatching failure is limited in terms of both its underpinning mechanisms and its occurrence across different populations. It is widely acknowledged that rates of hatching failure are higher in threatened species and in populations maintained in captivity compared to wild, non‐threatened species, but these differences have rarely been quantified and any broader patterns remain unexplored. To examine the associations between threat status, management interventions, and hatching failure across populations we conducted a phylogenetically controlled multilevel meta‐analysis across 231 studies and 241 species of birds. Our data set included both threatened (Critically Endangered, Endangered, and Vulnerable) and non‐threatened (Near Threatened and Least Concern) species across wild and captive populations, as well as ‘wild managed’ (‘free‐living’) populations. We found the mean overall rate of hatching failure across all populations to be 16.79%, with the hatching failure rate of wild, non‐threatened species being 12.40%. We found that populations of threatened species experienced significantly higher mean hatching failure than populations of non‐threatened species. Different levels of management were also associated with different rates of hatching failure, with wild populations experiencing the lowest rate of hatching failure, followed by wild managed populations, and populations in captivity experiencing the highest rate. Similarly, populations that were subject to the specific management interventions of artificial incubation, supplementary feeding, and artificial nest provision displayed significantly higher rates of hatching failure than populations without these interventions. The driver of this correlation between hatching failure and management remains unclear, but could be an indirect result of threatened species being more likely to have lower hatching success and also being more likely to be subject to management, indicating that conservation efforts are fittingly being focused towards the species potentially most at risk from extinction. This is the most comprehensive comparative analysis of avian hatching failure that has been conducted to date, and the first to quantify explicitly how threat status and management are associated with the rate of hatching failure in a population. We discuss the implications of our results, focusing on their potential applications to conservation. Although we identified several factors clearly associated with variation in hatching failure, a significant amount of heterogeneity was not explained by our meta‐analytical model, indicating that other factors influencing hatching failure were not included here. We discuss what these factors might be and suggest avenues for further research. Finally, we discuss the inconsistency in how hatching failure is defined and reported within the literature, and propose a standardised definition to be used in future studies which will enable better comparison across populations and ensure that the most accurate information is used to support management decisions.
