Orientation of juvenile barn swallows (<Emphasis Type="Italic">Hirundo rustica</Emphasis>) tested in Emlen funnels during autumn migration

Although hirundines have been used extensively in homing experiments, to date no investigation of their migratory orientation has been carried out, despite the well-known migratory habits of many species of this family. This paper reports on a study of the orientation of the barn swallow (Hirundo rustica), a typical diurnal trans-Saharan migrant. Modified Emlen funnels were used to verify the suitability of this species for cage experiments and investigate the role of visual and magnetic cues during the birds first migratory journey. Juvenile swallows were mist-netted at a roost site in central Italy and then tested in a site 19 km apart. Orientation experiments were performed under four experimental conditions: natural clear sky and simulated overcast, in both local and shifted magnetic fields (magnetic North=geographical West). Under clear sky, the swallows tended to orient phototactically toward the best-lit part of the funnel and failed to respond to the magnetic field shift. Under overcast conditions, they oriented northward and modified their directional choices as expected in response to the shifted magnetic North. On the whole, our data indicate that swallows can use magnetic information for compass orientation. Possible explanations for the northward orientation of birds tested under overcast conditions are discussed.Communicated by W. Wiltschko     

Reproductive isolation between intertidal and subtidal<Emphasis Type="Italic"> Scoloplos armiger</Emphasis> (Polychaeta,Orbiniidae) indicates sibling species in the North Sea

Two distinct modes of development in the common polychaete Scoloplos armiger (O. F. Müller, 1776) occur in the North Sea region: holobenthic development in egg cocoons and pelagic larvae hatching from suspended eggs. In the northern Wadden Sea near the island of Sylt, we observed that egg cocoons are produced intertidally while pelagic larvae originate from the adjacent subtidal zone. A previous genetic comparison between these subtidal and intertidal populations revealed distinct gene pools, suggesting that reproductive differences are not phenotypic but heritable. In this study, crossbreeding experiments show that intertidal and subtidal populations are reproductively isolated. Couples with males and females from different habitats had no offspring. Production of egg cocoons is determined by female origin from the intertidal zone. Pelagic larvae occurred only in couples with subtidal females and subtidal males. Intertidal males have spermatozoa with heads twice as long as those from subtidal males and a significantly shorter flagellum. We suspect that deviating sperm morphology may cause the reproductive breakdown at the fertilization stage. Juveniles hatching from cocoons have shorter anal cirri compared to juveniles that metamorphosed from pelagic larvae. We conclude there to be two sympatric sibling species in S. armiger: 'type I' in intertidal areas, which have egg cocoons, no pelagic larvae, elongated sperm heads, shortened sperm flagella and anal cirri; and a subtidal 'type S', lacking egg cocoons but with pelagic larvae, short sperm heads, long sperm flagella and anal cirri.Communicated by O. Kinne, Oldendorf/Luhe     

When to pay the cost of reproduction? A brood size manipulation experiment in great tits (<Emphasis Type="Italic">Parus major</Emphasis>)

Parental investment (PI) theory assumes that optimal parental investment is a function of expected cost/benefit ratio of current versus future reproduction. This study tests the prediction of PI theory that in a species with high adult mortality, paying of reproductive costs can be induced or prevented by manipulation of brood reproductive value (RV). Analysis of recruitment rates in a 10-year study of great tits (Parus major) showed that brood RV was affected by both fledgling number and quality (body mass and tarsus length). A 4-year brood size manipulation experiment (±2 hatchlings) resulted in reduction of fledgling quality in enlarged versus control and reduced broods, while the fledgling number did not differ between manipulation categories due to increase of nestling mortality with brood size manipulation score. Hence, the experiment resulted in reduction of brood RVs in enlarged broods. Females rearing enlarged broods survived better than those with control and reduced broods, while male survival was not affected by the experiment. This indicates that paying the survival costs for reproduction was a part of normal life history for studied female great tits, and that decisions whether to pay this cost were based on the estimation of brood RV. Recruitment rate was lowest (but extremely male-biased) in reduced broods, while control and increased broods did not differ in the number of locally recaptured offspring.     

Nutritional phagostimulants function as male courtship pheromone in the German cockroach, <Emphasis Type="Italic">Blattella germanica</Emphasis>

Summary. Males of the German cockroach, Blattella germanica, secrete a pheromonal substance from the abdominal tergal glands, which elicits a feeding response in females during the sequential courtship behavior. The nuptial secretion consists predominantly of a synergistic mixture of sugars and phospholipids. Cholesterol and a series of amino acids, which are also components of the males glandular secretion, significantly enhanced the phagostimulant activity of the sugar components. The nuptial feeding behavior of the female cockroach is therefore elicited by a complex assortment of nutritive components in the male tergal secretion, including sugars, phospholipids, cholesterol, and amino acids. These results indicate that a mixture of primary metabolites, and not of specific secondary metabolites, serves as a pheromonal cue that appeals to the females gustatory sense and effectively brings her to the precopulatory position. Although the male secretion consists of nutrients, we suggest that these compounds probably do not represent a significant nutrient investment in females and their progeny but rather function as a signal in the mating sequence of B. germanica.     

Habitat selection in a coastal dolphin species (<Emphasis Type="Italic">Cephalorhynchus hectori</Emphasis>)

Hector's dolphin ( Cephalorhynchus hectori) is a small New Zealand delphinid with a coastal distribution. Within a strip of 1 km from shore, the present study quantified the habitat used by the dolphins ( n=461 groups) over a 19-month period (216 field days with 966 survey hours) by recording the abiotic factors sea surface temperature (SST), water depth and water clarity. Resource selection functions were used to distinguish the properties of 461 "used" sites (dolphins present) from 425 "unused" sites (no dolphins present) in six different study areas. Most dolphins were encountered in waters <39 m depth, with <4 m Secchi disk visibility and >14°C temperature. The preference of Hector's dolphins for warm and turbid waters was tested using eight models. Water depth, water clarity, SST and the study area explained dolphin presence to a very significant degree ( p<0.001), and the model allowed the creation of probability plots for a variety of combinations of the variables. Habitat selection by dolphins differed between study areas, particularly between east and west coasts, in summer (December–February) and winter (June–August). Dolphin abundance appeared to change seasonally in some study areas, possibly due to a more offshore distribution of their prey in the winter, with its lower SSTs. This was so especially in summer (the main reproductive season), when dolphins (frequently with calves) occupied shallow and turbid waters, whereas in winter less use was made of this habitat.     

Fungi and wind strongly influence the temporal availability of logs in an old-growth spruce forest.

Coarse woody debris (CWD) is a key habitat for many species in forest ecosystems. To ensure the long-term survival of such species, forest management regimes must include measures that promote dead wood dynamics similar to those of natural forests. Thus, information on CWD dynamics under natural conditions is required, including data pertaining to the underlying agents of disturbance. This study examines modes of mortality, decay rates, and temporal patterns in the availability of Picea abies logs in a Swedish old-growth forest affected by internal, small-scale disturbance. All 684 logs in a 6.6-ha plot were mapped and classified into one of six decay classes. Logs in the early stages of decay were examined for the presence of heart-rot fungi. Six years later all logs were re-inventoried, including newly formed logs. Matrix models based on the transition rates between decay classes showed that it took about 60 years for 90% of the logs to decay beyond class 6 (a deformed trunk with soft wood). Large logs (> 26 cm) decayed 40% more slowly than small logs (< 25 cm). The initial volume of logs was 37.6 m3/ha but increased to 44.8 m3/ha after six years. In addition, there was a large shift in the decay-class distribution. The volume of logs in early and late decay classes increased by 71% and 45%, respectively, while the volume of logs in the intermediate decay classes decreased by 32%. The fluctuations appear to result from pulses in mortality, driven by a combination of strong winds and the heart-rot fungus, Phellinus chrysoloma, which was present in more than 30% of all logs at an early stage of decay. These results show that large temporal fluctuations in dead wood also occur in the absence of large-scale disturbance, and that heart-rot fungi are important factors driving the overall dynamics of dead wood. Since many wood-inhabiting species are naturally rare and have very specific substrate demands, such temporal variability in dead wood availability may have effects on biodiversity and should be taken into account when designing small, protected forest areas.     

Effects of fertilization and elevated CO<Subscript>2</Subscript> on larval food and butterfly nectar amino acid preference in<Emphasis Type="Italic"> Coenonympha pamphilus</Emphasis> L.

The effects of larval diet on the nutritional preferences of butterflies has rarely been examined. This study investigates whether alterations in the larval diet result in changes in adult preferences for nectar amino acids. Larvae of Coenonympha pamphilus were raised on fertilized or unfertilized Festuca rubra, grown under ambient (350 ppm) or elevated (750 ppm) atmospheric CO ₂environments. Fertilization led to marked increases in leaf nitrogen concentration. In plants grown under elevated CO ₂conditions, leaf water and nitrogen concentrations were significantly lower, and the C/N-ratio increased significantly. Fertilization of the host plant shortened the development time of C. pamphilus larvae, and pupal weight increased. In contrast, larvae of C. pamphilus developed significantly slower on F. rubra grown under elevated CO ₂, but adult emergence weight was not affected by CO ₂treatment of the plant. C. pamphilus females showed a clear preference for nectar mimics containing amino acids, whereas males, regardless of treatment, either preferred the nectar mimic void of amino acids or showed no preference for the different solutions. Female butterflies raised on fertilized plants showed a significant decline in their preference for nectar mimics containing amino acids. A slight, but not significant, trend towards increased nectar amino acid preference was found in females raised on plants grown under elevated CO ₂. We clearly demonstrate that alterations in larval host quality led to changes in butterfly nectar preferences. The ability of the butterfly to either rely less on nectar uptake or compensate for poor larval conditions represents a trade-off between larval and adult butterfly feeding.     

Enzymatische Umsetzung von Arsenkampfstoffen durch das Pilzenzym Mangan-Peroxidase

Degradation of organo-arsenical chemical warfare agents by fungal enzyme manganese peroxidase. The fungal enzyme manganese peroxidase was used to degrade different organo-arsenical chemical warfare agents in cell-free reaction mixtures (in vitro). The decrease in the concentration of arsenical chemical warfare agents was determined by gas chromatography after derivatization with thiols. All organo-arsenical compounds tested were converted by room temperature for more than 90%. Aliphatic arsenical compounds were attacked more rapidly than aromatic derivatives.     

Factors affecting vigilance within wild mixed-species troops of saddleback (<Emphasis Type="Italic">Saguinus fuscicollis</Emphasis>) and moustached tamarins (<Emphasis Type="Italic">S. mystax</Emphasis>)

We examine vigilance within a mixed-species troop of saddleback (Saguinus fuscicollis) and moustached (S. mystax) tamarins over a complete year. Saddleback tamarins were consistently more vigilant than moustached tamarins. This may be linked to their preference for lower strata. In accordance with previous studies of other primates, vigilant tamarins of both species were significantly further away from their nearest neighbours, and were also at lower heights in the forest than non-vigilant individuals. There was no observed sex difference in the amount of time spent vigilant. In terms of modes of scanning, the saddleback tamarins looked up significantly more frequently than the moustached tamarins, whereas there was no difference between the species in the frequency of side sweeps. There were no differences between the sexes in the frequencies of either type of vigilant behaviour. The proportion of time spent vigilant was higher than average immediately prior to entering a sleeping site for saddleback tamarins, but not for moustached tamarins. Both species were more vigilant immediately after exiting a sleeping site than at other times of the day. There was significant variation in the amount of time devoted to vigilance over the course of the year. These findings are discussed with respect to the social structure, ecology and main predator threats facing these species.Communicated by D. Watts     

湖南木兰科植物资源的调查研究

本文分析了湖南木兰科分布的自然条件,结合其形态性状讨论了它们的分类学问题、地理分布特点、资源状况以及自然生长状况。文末提出了湖南省木兰科的保护植物名单。