Breeding success of a brood parasite is associated with social mating status of its host

Reproductive success of brood parasites varies considerably both among and within host species, mainly due to differences in host egg-rejection rates and survival of parasitic chicks. Here, we investigated the breeding success of the cuckoo (Cuculus canorus) in one of its major hosts, the great reed warbler (Acrocephalus arundinaceus), with respect to host social mating status. In this passerine, polygynous males provide less parental care to their young per nest than monogamous males. Consequently, their less-assisted females may fledge lower numbers of nestlings than monogamous females. This may be especially true for secondary females, which often receive limited or no paternal help with young at all. Based on these findings, we expected higher cuckoo reproductive success in nests of socially monogamous than polygynous great reed warbler males. More specifically, we predicted lower fledging success of cuckoo young in nests of secondary than primary or monogamous females. In line with the prediction, we found higher cuckoo fledging success in nests of monogamous than polygynous males, monogamous nests being more than twice as successful as secondary nests. We detected, however, only a tendency to lower cuckoo success in primary compared to monogamous nests and no differences between primary and secondary nests. Moreover, neither parasitism nor host egg-rejection rates differed among the nests of different status. Our results show, for the first time, that the social mating status of a host may influence the overall reproductive success of a brood parasite and thus should be considered in further studies.     

Geographic bias in citation rates of conservation research

We investigated whether the impact of conservation science is greater for research conducted in countries with more pressing conservation problems. We quantified research impact for 231 countries based on 2 citation metrics (mean cites per paper and h index) and fitted models predicting research impact based on number of threatened bird and mammal species (as a measure of conservation importance of a country) and a range of demographic variables. Citation rates of conservation research increased as a country's conservation need increased and as human population, quality of governance, and wealth increased. Even after accounting for these factors, citation rates among regions and countries within regions varied significantly. The conservation research community needs to consider ways to begin addressing the entrenched disadvantages some countries have when it comes to initiating projects and producing high‐quality research.     

Adaptive superparasitism and patch time allocation in solitary parasitoids : the influence of pre-patch experience

Summary Dynamic optimal diet models predict that host selection decisions and patch time allocation are influenced by the resource value of the habitat. We tested these predictions using the solitary' parasitoid Leptopilina heterotoma. Assuming that travel times between patches, the quality of previously visited patches and parasitoid density affect the parasitoids' estimation of the resource value of the habitat, different treatments were given before introducing parasitoids singly to a patch containing 5 unparasitized and 15 parasitized hosts. The decision to superparasitize is only slightly influenced by the rate of patch encounter. The quality of the previously visited patch has a strong influence. When a poor patch has been visited on the previous day, more superparasitism is observed in the partly depleted patch than when a rich patch has been searched. More superparasitism is also observed when the parasitoids are kept with conspecifics before the experiment than when they are kept alone. Increasing patch residence times are observed as the quality of the previously presented patch decreases. Host selection decisions and patch time allocation are thus clearly influenced by the pre-patch experience of the parasitoid, as predicted by dynamic optimal diet models. This can also explain why females that have never oviposited in unparasitized hosts will superparasitize readily. Correspondence to: M.E. Visser     

Catalytic NOx reduction with simultaneous dioxin and furan oxidation

The engineering, construction, performance and running costs of a catalytic flue gas cleaning component in the low dust area of a municipal waste incinerator is discussed. For this purpose, the case study of a Flemish incineration plant is presented, covering the history, the design procedure of the catalyst, relevant process data and the financial aspects. A reliable PCDD/F-destruction by means of oxidation by the catalyst to typical values of 0.001 ng TEQ/Nm3 has been demonstrated. At the same time, NOx- and CO-emissions are reduced by 90% and 20% to about 50 mg/Nm3 and below 10 mg/Nm3, respectively.     

Sorption of cobalt and nickel on anaerobic granular sludges: isotherms and sequential extraction

The objective of this study was to investigate the sorption capacity and the fractionation of sorbed nickel and cobalt onto anaerobic granular sludges. Two different anaerobic granular sludges (non-fed, pH=7) were loaded with nickel and cobalt in adsorption experiments (monometal and competitive conditions). The combination of sequential extraction with the sorption isotherm analysis allowed the assessment of the sorption capacity of individual fractions present in the anaerobic granular sludges. The operational fractionation of the sorbed heavy metals was determined using a modified Tessier sequential extraction procedure. The sorption characteristics of each extracted fraction (exchangeable, carbonates, organic matter/sulfides and residual fractions) fitted well to the Langmuir model. The organic matter/sulfides fraction showed the highest affinity for cobalt and nickel in both sludges investigated compared to the other operationally defined fractions. The presence of iron negatively affected cobalt and nickel accumulation in this organic matter/sulfides fraction. The trace metals-iron sulfide interactions are likely to be the key process in controlling the distribution of cobalt and nickel during sorption onto non-fed methanogenic granules due to the high affinity of iron sulfides towards the metals studied.     

Inter-sexual conflicts over copulations in the European starling: evidence for the female mate-guarding hypothesis

Recent studies have suggested that conflicts of interests between the sexes may lead to variation in copulation behavior among pairs. We examined differences in the rate and timing of copulation solicitations and copulations among females of different mating status in the facultatively polygynous starling in an attempt to explain why females copulate repeatedly with their mate. All within-pair copulations were female-solicited indicating that females control copulations in the starling. Before egg laying, females solicited copulations at a high rate (usually more than 2 per hour). In contrast to most other species studied so far, females continued to solicit copulations throughout the egg laying period, and also solicited after egg laying (the latest solicitation occurred when the nestlings were 4 days old). Primary females solicited more copulations than monogamous females both during and after the fertile period. Many copulation solicitations of primary females occurred at the nestbox where their male was singing to obtain an extra female. Both primary and secondary females solicited more copulations after the egg-laying period than monogamous females. A large proportion of female copulation solicitations was refused by the male partner: female solicitation resulted in more male refusals in primary females than in monogamous females. Primary females were more likely to be chased aggressively when they solicited a copulation than monogamous females; most aggressive chases occurred when primary females flew towards their male to solicit copulation when he was singing at another nestbox. Overall, our results demonstrate that there is a conflict over copulation between males and females in polygynous pairs. The conflict presumably relates to the cost of sharing male parental investment: females use copulation solicitation behavior to interrupt their singing males apparently in an attempt to prevent them from becoming polygynous. We present the first empirical evidence that female songbirds use copulation solicitation behavior as a form of mate guarding, often in a non-reproductive context. We did not find a positive relationship between copulation rate during the fertile period and the amount of male parental care as is predicted by the paternity confidence hypothesis.     

Is external contamination with organic pollutants important for concentrations measured in bird feathers?

Although there is increasing evidence that bird feathers can be used as a non-destructive biomonitoring tool for organic pollutants [such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and p,p'-dichlorodiphenyl-trichloroethane and metabolites (DDTs)], the importance of external contamination of these organic pollutants onto the feathers has not been considered. Here we examine to which extent external contamination of organic pollutants occurs onto the feathers of a predatory bird. We have analysed primary wing feathers of 16 common buzzards (Buteo buteo) collected in Belgium. In order to study differences in external contamination within and among wing feathers, the vane and the shaft of each feather were separated and were analysed in parallel, pooled for the three inner and the three outer primary wing feathers. Most organic pollutants could be measured in these pooled samples of both the vane and the shaft. Concentrations of hexachlorobenzene (HCB), DDTs, PCBs and PBDEs were significantly higher in the vane compared to the shaft. The profiles of PCBs and PBDEs in the shaft closely resembled the profiles in liver and muscle tissue, in contrast with the profile of the vane. The PBDE congeners 47, 99 and 153 had a similar contribution in shafts of primary feathers of common buzzards. Although these results suggest that external contamination could be important on the vane, no differences in the profile of PBDEs or PCBs were found between the inner and outer (more exposed) primary feathers. Furthermore, correlation coefficients with internal tissues were not univocally distinct between the shaft and the vane. Therefore our results indicate that the higher concentrations found in the vane in comparison to the shaft do not originate from external contamination via the air, but that other factors such as structure and chemical properties of the feathers may be of importance. The lack of significant external contamination onto the feather surface is an additional asset for the use of feathers as a non-destructive biomonitor for organic pollutants.     

Potential malaria outbreak in Germany due to climate warming: risk modelling based on temperature measurements and regional climate models

Purpose  

Climate warming can change the geographic distribution and intensity of the transmission of vector-borne diseases such as malaria. The transmitted parasites usually benefit from increased temperatures as both their reproduction and development are accelerated. Lower Saxony (northwestern Germany) has been a malaria region until the 1950s, and the vector species are still present throughout Germany. This gave reason to investigate whether a new autochthonous transmission could take place if the malaria pathogen was introduced again in Germany.     

Maternal transfer of organochlorines and brominated flame retardants in blue tits (Cyanistes caeruleus)

Although eggs have frequently been used as a biomonitoring tool for contamination with organohalogenated pollutants (OHPs), few studies have investigated the processes of maternal transfer in birds. Here, maternal transfer of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was investigated through comparison of the concentrations and profiles between whole homogenised female blue tits (Cyanistes caeruleus) and their eggs. In addition, we examined if there was an effect of laying order on the concentrations of PCBs, OCPs and PBDEs. PCBs were the most abundant contaminants in female blue tits and their eggs, followed by OCPs and PBDEs. Among the OCPs, p,p'-DDE was the most dominant compound and accounted for more than 80% of the sum OCPs. Egg concentrations decreased significantly in relation to the laying order from 1623+/-148 ng/g lipid weight (lw) to 1040+/-47 ng/g lw for the sum PCBs, from 342+/-24 ng/g lw to 235+/-17 ng/g lw for the sum OCPs and from 49+/-5 ng/g lw to 27+/-5 ng/g lw for the sum PBDEs. When reviewing all studies investigating laying order effects of OHPs in birds, no clear patterns emerged, which may be due to differences in study species and methodology among studies. Despite the fact that there were laying order effects in blue tit clutches, the variance in concentrations of PCBs and PBDEs was larger among clutches than within clutches. Variance in OCP concentrations among clutches was similar to the variance within clutches. These results suggest that one randomly collected blue tit egg from a clutch is useful as biomonitoring tool for PCBs and PBDEs, while for OCPs it is recommended to consistently use the same egg from the laying sequence as a biomonitoring tool. Lipid-normalized concentrations of sum PCBs, sum OCPs and sum PBDEs in female blue tits after clutch completion were comparable to the concentrations in the first-laid eggs. The egg/female lipid concentration ratios for sum PCBs, sum OCPs and sum PBDEs decreased significantly from 1.0+/-0.09 to 0.7+/-0.003, 1.1+/-0.1 to 0.7+/-0.02 and 1.2+/-0.14 to 0.8+/-0.05, respectively, during the course of egg laying. The profiles of the females and eggs differed significantly for the PCBs, OCPs and PBDEs. There was a higher contribution of lower chlorinated PCB congeners (CB 28, CB 52, CB 95, CB 101 and CB 110), BDE 183, p,p'-DDT and other less persistent OCPs in the females compared to their eggs. Maternal transfer in blue tits seemed to be selective for the more bioaccumulative and persistent congeners/compounds.