Phenology and flock size of migrating Great Cormorants (Phalacrocorax carbo) during autumn migration in central North Rhine-Westphalia

Während über Brutbestandsentwicklung und Phänologie rastender Kormorane viel bekannt ist, gibt es kaum Angaben zum aktiven Zug der Art abseits der Küsten. Die wenigen Arbeiten stammen meist aus älteren Untersuchungen, als der Kormoran augrund geringer europäischer Brutbestände noch ein seltener Durchzügler war. Anhand von Zugvogelplanbeobachtungen mit langer jahreszeitlicher und tageszeitlicher Ausdehnung aus den Jahren 2001 und 2003 wird der jahreszeitliche und tageszeitliche Ablauf des Wegzuges über Mittelwestfalen beschrieben. Auch Angaben zu Truppstärken ziehender Kormorane werden gemacht. Dabei zeigt sich, dass Kormorane jahreszeitlich etwas später, weiter über den Tag verteilt und offenbar auch in größeren Trupps durch das Binnenland ziehen als an der Küste. Insgesamt können somit einige Wissenslücken über den aktiven Zugverlauf abseits der Küsten geschlossen werden.The recent increase in the breeding population and the phenology of roosting Great Cormorants (Phalacrocorax carbo) are well described, but little is known about their migration patterns away from coastal areas. The few published data are based on older investigations, when the Cormorant was a rare breeding bird in Europe and thus a very rare migratory bird in inland parts of Central Europe. As a result of daily migration counts carried out in central North Rhine-Westphalia from mid-August to mid-November during 2001 and 2003, I describe migration patterns both throughout the autumn and within a day. Additionally, flock sizes are shown. Inland Cormorants migrate later in the season, seem to migrate in bigger flocks, and do not concentrate their movements to a particular time of the day, compared to birds at the coast. The presented data provide a valuable insight into the migration of these birds within Central Europe

Successful breeding of a Common Buzzard Buteo buteo in a cliff nest inside a quarry in Northwest Germany

Im Jahre 2005 wurde in einem Steinbruch in Geseke in Nordrhein-Westfalen eine Felsbrut eines Mäusebussards Buteo buteo entdeckt. Während Felsnester in Großbritannien und den Alpen zumindest gebietsweise vorkommen und teilweise sogar häufig sind, werden für Mitteleuropa außerhalb der Alpen lediglich einige Bodenbruten beschrieben, jedoch keine Bruten auf Felsen. Obwohl ein Uhupaar Bubo bubo seit einigen Jahren im selben Teil des Steinbruches brütet, wurden drei junge Mäusebussarde flügge.In 2005, an occupied cliff nest of a Common Buzzard was found in a quarry near Geseke in North Rhine-Westphalia, Northwest Germany. Cliff nests are common in Great Britain and parts of the Alps, but in Central Europe tree nests are the rule. The relevant literature describes only a few nests on the ground, but none on cliffs. Despite the breeding of a pair of Eagle Owls Bubo bubo in the same area of the quarry for some years, three young Buzzards fledged

Experimental facilitation of heat loss affects work rate and innate immune function in a breeding passerine bird

The capacity to get rid of excess heat produced during hard work is a possible constraint on parental effort during reproduction [heat dissipation limit (HDL) theory]. We released hard-working blue tits (Cyanistes caeruleus) from this constraint by experimentally removing ventral plumage. We then assessed whether this changed their reproductive effort (feeding rate and nestling size) and levels of self-maintenance (change in body mass and innate immune function). Feather-clipped females reduced the number of feeding visits and increased levels of constitutive innate immunity compared with unclipped females but did not fledge smaller nestlings. Thus, they increased self-maintenance without compromising current reproductive output. In contrast, feather clipping did not affect the number of feeding visits or innate immune function in males, despite increased heat loss rate. Our results show that analyses of physiological parameters, such as constitutive innate immune function, can be important when trying to understand sources of variation in investment in self-maintenance versus reproductive effort and that risk of overheating can influence innate immune function during reproduction

Offspring pay sooner, parents pay later:Experimental manipulation of body mass reveals trade-offs between immune function, reproduction and survival

Introduction: Life-history theory predicts that organisms trade off survival against reproduction. However, the time scales on which various consequences become evident and the physiology mediating the cost of reproduction remain poorly understood. Yet, explaining not only which mechanisms mediate this trade-off, but also how fast or slow the mechanisms act, is crucial for an improved understanding of life-history evolution. We investigated three time scales on which an experimental increase in body mass could affect this trade-off: within broods, within season and between years. We handicapped adult skylarks (Alauda arvensis) by attaching extra weight during first broods to both adults of a pair. We measured body mass, immune function and return rates in these birds. We also measured nest success, feeding rates, diet composition, nestling size, nestling immune function and recruitment rates.Results: When nestlings of first broods fledged, parent body condition had not changed, but experimental birds experienced higher nest failure. Depending on the year, immune parameters of nestlings from experimental parents were either higher or lower than of control nestlings. Later, when parents were feeding their second brood, the balance between self-maintenance and nest success had shifted. Control and experimental adults differed in immune function, while mass and immune function of their nestlings did not differ. Although weights were removed after breeding, immune measurements during the second brood had the capacity to predict return rates to the next breeding season. Among birds that returned the next year, body condition and reproductive performance a year after the experiment did not differ between treatment groups.Conclusions: We conclude that the balance between current reproduction and survival shifts from affecting nestlings to affecting parents as the reproductive season progresses. Furthermore, immune function is apparently one physiological mechanism involved in this trade-off. By unravelling a physiological mechanism underlying the trade-offs between current and future reproduction and by demonstrating the different time scales on which it acts, our study represents an important step in understanding a central theory of life-history evolution.</p

Parental morph combination does not influence innate immune function in nestlings of a colour-polymorphic African raptor

Conditions experienced during early life can have long-term individual consequences by influencing dispersal, survival, recruitment and productivity. Resource allocation during development can have strong carry-over effects onto these key parameters and is directly determined by the quality of parental care. In the black sparrowhawk (Accipiter melanoleucus), a colour-polymorphic raptor, parental morphs influence nestling somatic growth and survival, with pairs consisting of different colour morphs ('mixed-morph pairs') producing offspring with lower body mass indices, but higher local apparent survival rates. Resource allocation theory could explain this relationship, with nestlings of mixed-morph pairs trading off a more effective innate immune system against somatic growth. We quantified several innate immune parameters of nestlings (hemagglutination, hemolysis, bacteria-killing capacity and haptoglobin concentration) and triggered an immune response by injecting lipopolysaccharides. Although we found that nestlings with lower body mass index had higher local survival rates, we found no support for the proposed hypothesis: neither baseline immune function nor the induced immune response of nestlings was associated with parental morph combination. Our results suggest that these immune parameters are unlikely to be involved in providing a selective advantage for the different colour morphs' offspring, and thus innate immunity does not appear to be traded off against a greater allocation of resources to somatic growth. Alternative hypotheses explaining the mechanism of a low nestling body mass index leading to subsequent higher local survival could be related to the post-fledgling dependency period or differences in dispersal patterns for the offspring from different morph combinations

Environmental proxies of antigen exposure explain variation in immune investment better than indices of pace of life.

Investment in immune defences is predicted to covary with a variety of ecologically and evolutionarily relevant axes, with pace of life and environmental antigen exposure being two examples. These axes may themselves covary directly or inversely, and such relationships can lead to conflicting predictions regarding immune investment. If pace of life shapes immune investment then, following life history theory, slow-living, arid zone and tropical species should invest more in immunity than fast-living temperate species. Alternatively, if antigen exposure drives immune investment, then species in antigen-rich tropical and temperate environments are predicted to exhibit higher immune indices than species from antigen-poor arid locations. To test these contrasting predictions we investigated how variation in pace of life and antigen exposure influence immune investment in related lark species (Alaudidae) with differing life histories and predicted risks of exposure to environmental microbes and parasites. We used clutch size and total number of eggs laid per year as indicators of pace of life, and aridity, and the climatic variables that influence aridity, as correlates of antigen abundance. We quantified immune investment by measuring four indices of innate immunity. Pace of life explained little of the variation in immune investment, and only one immune measure correlated significantly with pace of life, but not in the predicted direction. Conversely, aridity, our proxy for environmental antigen exposure, was predictive of immune investment, and larks in more mesic environments had higher immune indices than those living in arid, low-risk locations. Our study suggests that abiotic environmental variables with strong ties to environmental antigen exposure can be important correlates of immunological variation.Financial support came from the Schure-Beijerinck-Poppings Fonds (to NPCH and AH), BirdLife Netherlands (to BIT), NSF grant IBN 0212587 (to JBW), and VENI and VIDI grants from the Netherlands Organisation for Scientific Research (to KDM and BIT).This is the accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007%2Fs00442-014-3136-y

Innate immune function and antioxidant capacity of nestlings of an African raptor covary with the level of urbanisation around breeding territories

Urban areas provide breeding habitats for many species. However, animals raised in urban environments face challenges such as altered food availability and quality, pollution and pathogen assemblages. These challenges can affect physiological processes such as immune function and antioxidant defences which are important for fitness. Here, we explore how levels of urbanisation influence innate immune function, immune response to a mimicked bacterial infection and antioxidant capacity of nestling Black Sparrowhawks Accipiter melanoleucus in South Africa. We also explore the effect of timing of breeding and rainfall on physiology since both can influence the environmental condition under which nestlings are raised. Finally, because urbanisation can influence immune function indirectly, we use path analyses to explore direct and indirect associations between urbanisation, immune function and oxidative stress. We obtained measures of innate immunity (haptoglobin, lysis, agglutination, bactericidal capacity), indices of antioxidant capacity (total non-enzymatic antioxidant capacity (tAOX) and total glutathione from nestlings from 2015 to 2019. In addition, in 2018 and 2019, we mimicked a bacterial infection by injecting nestlings with lipopolysaccharide and quantified their immune response. Increased urban cover was associated with an increase in lysis and a decrease in tAOX, but not with any of the other physiological parameters. Furthermore, except for agglutination, no physiological parameters were associated with the timing of breeding. Lysis and bactericidal capacity, however, varied consistently with the annual rainfall pattern. Immune response to a mimicked a bacterial infection decreased with urban cover but not with the timing of breeding nor rainfall. Our path analyses suggested indirect associations between urban cover and some immune indices via tAOX but not via the timing of breeding. Our results show that early-life development in an urban environment is associated with variation in immune and antioxidant functions. The direct association between urbanisation and antioxidant capacity and their impact on immune function is likely an important factor mediating the impact of urbanisation on urban-dwelling animals. Future studies should explore how these results are linked to fitness and whether the responses are adaptive for urban-dwelling species