Search

The species complex comprising the rufous-naped lark Corypha africana , Sharpe's lark Corypha sharpii , the red-winged lark Corypha hypermetra , the Somali long-billed lark Corypha somalica and Ash's lark Corypha ashi encompasses 31 recognised taxa across sub-Saharan Africa, many of which are extremely poorly known and some not observed for decades. Only 17 taxa have been studied molecularly and none comprehensively for morphology, vocalisations or other behaviours. Here, we undertake comprehensive integrative taxonomic analyses based on plumage and morphometrics (for 97% of the taxa), mitochondrial and nuclear loci (77%), ≤ 1.3 million genome-wide single nucleotide polymorphisms (68%), song (many described for the first time; 52%) and additional behavioural data (45%). All polytypic species as presently circumscribed are paraphyletic, with eight primary clades separated by ≤ 6.3–6.8 Myr, broadly supported by plumage, morphometrics, song and other behaviours. The most recent divergences concern sympatric taxon pairs usually treated as separate species, whereas the divergence of all clades including C. africana subspecies is as old as sister species pairs in other lark genera. We propose the recognition of nine instead of five species, while C. ashi is synonymised with C. somalica rochei as C. s. ashi. The geographical distributions are incompletely known, and although the nine species are generally para-/allopatric, some might be sympatric. [ABSTRACT FROM AUTHOR]

The innate immune system is essential for survival, yet many immune traits are highly variable between and within individuals. In recent years, attention has shifted to the role of environmental factors in modulating this variation. A key environmental factor is food availability, which plays a major role in shaping life histories, and may affect resource allocation to immune function through its effect on nutritional state.We developed a technique to permanently increase foraging costs in seed‐eating birds, and leveraged this technique to study the effects of food availability on the innate immune system over a 3‐year period in 230 zebra finches housed in outdoor aviaries. The immune components we studied were haptoglobin, ovotransferrin, nitric oxide, natural antibodies through agglutination, complement‐mediated lysis, and killing capacity of Escherichia coli and Candida albicans, covering a broad spectrum of the innate immune system. We explored the effects of food availability in conjunction with other potentially important variables: season, age, sex and manipulated natal brood size.Increased foraging costs affected multiple components of the immune system, albeit in a variable way. Nitric oxide and agglutination levels were lower under harsh foraging conditions, while Escherichia coli killing capacity was increased. Agglutination levels also varied seasonally, but only at low foraging costs. C. albicans killing capacity was lower in winter, and even more so for animals in harsh foraging conditions that were raised in large broods. Effects of food availability on ovotransferrin were also seasonal, and only apparent in males. Haptoglobin levels were independent of foraging costs and season.Males had higher levels of immune function than females for three of the measured immune traits. Innate immune function was independent of age and manipulated natal brood size.Our finding that food availability affects innate immune function suggests that fitness effects of food availability may at least partially be mediated by effects on the immune system. However, food availability effects on innate immunity varied in direction between traits, illustrating the complexity of the immune system and precluding conclusions on the level of disease resistance. [ABSTRACT FROM AUTHOR]

Predation is one of the most relevant selective forces in nature. However, the physiological mechanisms behind anti‐predator strategies have been overlooked, despite their importance to understand predator–prey interactions. In this context, the immune system could be especially revealing due to its relationship with other critical functions and its ability to enhance prey's probabilities of survival to a predator's attack. Developing organisms (e.g. nestlings) are excellent models to study this topic because they suffer a high predation pressure while undergoing the majority of their development, which maximizes potential trade‐offs between immunity and other biological functions. Using common blackbirds Turdus merula as model species, we experimentally investigated whether an elevated nest predation risk during the nestling period affects nestlings' immunity and its possible interactions with developmental conditions (i.e. body condition and growth). Experimental nestlings modified some components of their immunity, but only when considering body condition and growth rate, indicating a multifaceted immunological response to predation risk and an important mediator role of nestlings' developmental conditions. Predation risk induced a suppression of IgY but an increase in lymphocytes in nestlings with poor body condition. In addition, experimental but not control nestlings showed a negative correlation between growth and heterophils, demonstrating that nest predation risk can affect the interaction between growth and immunity. This study highlights the importance of immunity in anti‐predator response in nestlings and shows the relevance of including physiological components to the study of predation risk. [ABSTRACT FROM AUTHOR]

Home‐range studies have received considerable attention from ecologists but are greatly skewed towards the north temperate areas. Tropical areas offer an ideal setting to tease apart hypotheses about weather, food availability and social interactions as important factors influencing home‐range. In this study, we investigated home‐range and movement patterns of the tropical Red‐capped Lark Callandrella cineria, a year‐round breeding bird with a dynamic social structure. We tracked 56 individuals using radiotransmitters and colour‐ring readings over a 23‐month period. Our objective was to understand year‐round variation in home‐range size in the context of the highly aseasonal and unpredictable variation in weather and resources typical of many equatorial habitats, in addition to the birds' changing social structure and year‐round breeding. The mean composite monthly home‐range of Red‐capped Larks was 58.0 ha, and the mean individual home‐range size was 19.9 ha, but this varied considerably between individuals. The total number of nests found per month (breeding intensity) best predicted home‐range size of non‐breeding birds, and of breeding and non‐breeding birds combined. We show for the first time that breeding intensity decreases the home‐range size of non‐breeding individuals. Our study also underlines the relevance of conducting more studies in aseasonal tropical areas in order to disentangle effects of weather, food availability and breeding that vary in parallel, peaking simultaneously in most seasonal areas. [ABSTRACT FROM AUTHOR]