Saisonaler Verlauf der Gesangsaktivit?t der Singdrossel(Turdus philomelos), mit Anmerkungen zum nachbrutzeitlichen Gesangsschub

Zusammenfassung Der Zürichbergwald ist eine 350 ha große, bewaldete Kuppe auf 480–680 m ü.M. am Rande der Stadt Zürich. Hier untersuchten wir von 1989 bis 1995 die jahreszeitliche Gesangsaktivität der Singdrossel mit zwei verschiedenen Ansätzen. 1989 und 1991–1995 zählte JH an 123 Tagen auf zwei festgelegten Strecken von 6,1 und 7,1 km die Sänger jeweils in der Stunde der abendlichen Dämmerung. Im gleichen Gebiet zählte RS 1990 an 46 Tagen auf einer 6,7 km langen Strecke am Morgen in der Stunde nach Sonnenaufgang. Ebenfalls 1990 sammelte RS Daten zur Brutbiologie.Die Gesangsaktivität definierten wir mit der Anzahl singender Männchen pro km. Im Jahresverlauf zeigen die Kurven der Morgen- und der Abendaktivität keinen Unterschied. Die Kurve ist deutlich dreiphasig: Ein erster Gesangsschub vom Eintreffen der Vögel bis zum 5. April, danach eine gesangsarme Zwischenzeit bis zum 15. Mai, gefolgt von einem zweiten Gesangsschub, welcher bis zum 5. Juli dauern kann. Allenfalls ist der erste Gesangsschub (stark zeitverschoben) mit dem Beginn der Erstbruten korreliert; die von vielen Singvögel bekannte, markante Gesangsaktivität unmittelbar vor der Eiablage gibt es nicht. Der zweite Gesangsschub ist in der Stärke mit dem ersten vergleichbar. Allerdings liegt er eindeutig am Ende der Brutzeit und kann nicht mit einem Brutparameter (Partnerfindung, Paarbindung, Balz, Brut-Stimulation) in Zusammenhang stehen. Die Funktion dieser nachbrutzeitlichen Gesangsaktivität scheint zukunftsbezogen zu sein. In Frage kommt gehäuftes Singen der Väter vor den Jungen zum Erlernen des Gesangs und des Dialekts, oder/und eine Revier-Voranzeige für die nänchste Brutsaison durch die als philopatrisch bekannten Männchen.

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Annual variation in singing activity of the Song Thrush(Turdus philomelos), with comments on high postbreeding song output

Summary This study was carried out at the Zürichbergwald, a forest east of Zurich (47°20N/08°30E). The study site is a wooded hill of 350 ha between 480 to 680 m asl, characterised by a BeechFagus silvatica forest with patches of SprucePicea abies on 25 % of its surface. The Zürichbergwald is a popular recreational area with moderate forestry exploitation. We did not differentiate acoustic registration from singing activity, and we considered the number of singing males per km to be a measure for singing activity. Two different approaches were applied: in 6 breeding seasons (1989 and 1991 to 1995) JH counted birds at sunset on a 6.1 or 7.1 km circuit (n=123). In 1990, the same was done by RS at dawn each morning on a zigzag track of 6.7 km (n=46). Also in 1990, RS sampled data on the breeding biology of the species.The annual cycle of morning and evening song activity was significantly correlated (Spearman's rank-test; p<0.001 comparing pentads, p=0.025 comparing half of months). Morning and evening revealed the same pattern: there was a first large peak of singing activity early in the year (earliest onset of singing 19 February 1989; latest 8 March 1993) until 5 April (phase I). A period of low song activity followed from 6 April to 15 May (phase II). The period from 16 May to (circa) 5 July was characterized by a second large peak (phase III). Each of the corresponding phases was comparable between morning and evening (Wilcoxon matching pairs; p>0.05). The analysis of evening data reveals that phase II differed from I and from III (p=0.05), but the last two did not differ significantly (Wilcoxon matching pairs; p>0.05).The day with the highest song activity fell in phase I twice (maximum 6.1 singing males/km, 2 April 1995) and 5 times in phase III (maximum 6.9 singing males/km, 23 May 1994).The date females first laid was determined for 53 out of 68 nests. The first brood started 25 March, the last 25 June 1990. Only 3 broods were initiated later than 5 June.The first peak of singing activity could be correlated with the (delayed) onset of breeding, but the second started at the end of the breeding season and persisted too long to be correlated with any breeding activity such as female attraction or stimulation, mate-guarding, etc. We postulate the high post-breeding song output to have several possible functions: Song instruction by father to offspring, or territory announcement for the next season.

     

Oviposition behavior of Anagrus nigriventris,an egg parasitoid of beet leafhopper, Circulifer tenellus

Oviposition behavior of Anagrus nigriventris,a parasitoid of the eggs of the beetleafhopper,Circulifer tenellus, wasdescribed on sugar beet. Ovipositor probes ofrelatively long duration were accompanied by a periodof abdominal vibrations toward the end of the probe. These periods began as high frequency, low amplitudevibrations in the abdomen, and climaxed as a tremblingof the whole body in an up and down direction.Oviposition by the parasitoid was associated with theoccurrence of abdominal vibrations during a probe andwith probe durations 50 s; however thepresence/absence of abdominal vibrations during aprobe was considered a more reliable indicator ofoviposition than was a threshold probe duration of 50s. The majority of probes (63% of all probes) were inempty plant tissue, lasted 15 s, and were notassociated with abdominal vibrations. While probeswithout abdominal vibrations at host egg sites (14%of all probes) lasted an average of 48 s, probes withabdominal vibrations at host egg sites (23% of allprobes) lasted an average of 102 s, and all were 50s. It is hypothesized that the relative frequency ofthe 3 types of probes could be affected by the degreeof wasp experience, by the level of host cues on thesubstrate, and by the relative importance of ovipositor probing (vs. antennation) in the hostdetection process. Data from the study suggest thatA. nigriventris is able to discriminate againstpreviously attacked host eggs.     

Optimal Foraging Theory and the Racecar Driver: The Impact of Student-Centered Learning on Anthropological Pedagogy

This article contributes to the field of anthropological pedagogy, adding to recent articles regarding needed change in anthropology teaching methods. All have in common the practice of anthropology in the classroom. The author used the theory of optimal foraging to encourage students to operationalize human behavior. The economic benefit that students reaped warrants discussion. Students rapidly and measurably improved several areas of their lifestyle including health, finance, and home. Pursuing an anthropology degree thus becomes a personal journey.     

"What if We Are Doing This All Wrong?": Sequestering and a Community of Practice

This article explores how sequestered novices within a community of practice struggled with their reliance on individual learning resources and identity development. In a year-long study at a child-care center that included methods of participant-observation, interviewing, videotaping, and apprenticeship, five inexperienced child-care teachers, including me, relied heavily on our creativity, recollections, learning by doing, and embodied experiences. I suggest that future studies of communities of practice examine instances of sequestering and include the perceptions of novices.     

Quantifying the Community: Using Bayesian Learning Networks to find Structure and Conduct Inference in Invasions Biology

One of the key obstacles to better understanding, anticipating, and managing biological invasions is the difficulty researchers face when trying to quantify the many important aspects of the communities that affect and are affected by non-indigenous species (NIS). Bayesian Learning Networks (BLNs) combine graphical models with multivariate Bayesian statistics to provide an analytical tool for the quantification of communities. BLNs can determine which components of a natural system influence which others, quantify this influence, and provide inferential analysis of parameter changes when changes in network variables are hypothesized or observed. After a brief explanation of these three functions of BLNs, a simulated network is analyzed for structure, parameter estimation, and inference. Discussion of this approach to invasions biology is explored and expanded applications for BLNs are then offered.     

A neural-network technique to learn concepts from electroencephalograms

A new technique is presented developed to learn multi-class concepts from clinical electroencephalograms (EEGs). A desired concept is represented as a neuronal computational model consisting of the input, hidden, and output neurons. In this model the hidden neurons learn independently to classify the EEG segments presented by spectral and statistical features. This technique has been applied to the EEG data recorded from 65 sleeping healthy newborns in order to learn a brain maturation concept of newborns aged between 35 and 51 weeks. The 39,399 and 19,670 segments from these data have been used for learning and testing the concept, respectively. As a result, the concept has correctly classified 80.1% of the testing segments or 87.7% of the 65 records.     

What Do Mexican Fruit Flies Learn When They Experience Fruit?

Mexican fruit flies learn fruit characteristics that enable them to distinguish familiar fruits from novel fruits. We investigated whether mature Mexican fruit flies learn fruit color, size or odor. We found no evidence that female flies learn fruit color or size after experience with host fruit, including oviposition. However, green fruit and fruit models were more attractive than yellow and red fruit and fruit models regardless of previous experience. Females with grapefruit experience were more attracted to fruit models with extract of either grapefruit peel or pulp, than to models without extract. Females with no experience with grapefruit were not attracted to models treated with grapefruit extract. These results indicate that females learned fruit odor during exposure to grapefruit.     

Docosahexaenoic acid provides protection from impairment of learning ability in Alzheimer's disease model rats

Docosahexaenoic acid (C22:6, n-3), a major n-3 fatty acid of the brain, has been implicated in restoration and enhancement of memory-related functions. Because Alzheimer's disease impairs memory, and infusion of amyloid-beta (Abeta) peptide (1-40) into the rat cerebral ventricle reduces learning ability, we investigated the effect of dietary pre-administration of docosahexaenoic acid on avoidance learning ability in Abeta peptide-produced Alzheimer's disease model rats. After a mini-osmotic pump filled with Abeta peptide or vehicle was implanted in docosahexaenoic acid-fed and control rats, they were subjected to an active avoidance task in a shuttle avoidance system apparatus. Pre-administration of docosahexaenoic acid had a profoundly beneficial effect on the decline in avoidance learning ability in the Alzheimer's disease model rats, associated with an increase in the cortico-hippocampal docosahexaenoic acid/arachidonic acid molar ratio, and a decrease in neuronal apoptotic products. Docosahexaenoic acid pre-administration furthermore increased cortico-hippocampal reduced glutathione levels and glutathione reductase activity, and suppressed the increase in lipid peroxide and reactive oxygen species levels in the cerebral cortex and hippocampus of the Alzheimer's disease model rats, suggesting an increase in antioxidative defence. Docosahexaenoic acid is thus a possible prophylactic means for preventing the learning deficiencies of Alzheimer's disease.     

Sexual experience interacts with steroid exposure to shape the partner preferences of rats

A three-phase experiment manipulated sexual experience and hormone exposure (perinatally and in adulthood) in female rats housed individually from weaning so as to limit peripubertal social and sexual experience. Noncontact partner preference for a male or estrous female rat was measured both before and after sexual experience, first while rats were under the influence of circulating testosterone propionate (TP) and later after priming them with ovarian hormones (estradiol benzoate and progesterone; EB & P). When implanted with TP capsules and tested while sexually naive, all groups of female rats preferred females to males without differing statistically. However, following three sexual experience sessions with estrous females, differences emerged between the masculinized and control groups in the magnitude of their female-directed preference, with masculinized females demonstrating a significantly greater preference for estrous females. Sexual experience with male rats under EB & P did not result in a significant shift in preference in any group. Histological assessment indicated that the volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) was increased by exposure to TP postnatally, and SDN-POA volume correlated positively with partner preference scores but only when rats were both sexually experienced and exposed to circulating TP in adulthood. These results suggest that sexual experience interacts with steroid exposure to shape partner preference.     

Does my mouse have Alzheimer's disease?

Small animal models that manifest many of the characteristic neuropathological and behavioral features of Alzheimer's disease (AD) have been developed and have proven of great value for studying the pathogenesis of this disorder at the molecular, cellular and behavioral levels. The great progress made in our understanding of the genetic factors that either cause or contribute to the risk of developing AD has prompted many laboratories to create transgenic (tg) mice that overexpress specific genes which cause familial forms of the disease. Several of these tg mice display neuropathological and behavioral features of AD including amyloid β-peptide (Aβ) and amyloid deposits, neuritic plaques, gliosis, synaptic alterations and signs of neurodegeneration as well as memory impairment. Despite these similarities, important differences in neuropathology and behavior between these tg mouse models and AD have also been observed, and to date no perfect animal model has emerged. Moreover, ascertaining which elements of the neuropathological and behavioral phenotype of these various strains of tg mice are relevant to that observed in AD continues to be a challenge. Here we provide a critical review of the AD-like neuropathology and behavioral phenotypes of several well-known and utilized tg mice that express human APP transgenes.