Foundations of bird surveys and implications for the collection and analysis of data in large-scale monitoring programs

Großräumige Monitoringprogramme stellen eine zweistufige Stichprobe dar: Zuerst wird eine räumliche Stichprobe ausgewählt und danach eine Stichprobe an beobachteten Individuen, besetzten Flächen oder Arten. Damit die in Monitoringprogrammen gewonnenen Zahlen interpretierbar bleiben, muss die räumliche Stichprobe „definiert zufällig“ erfolgen, ansonsten können Verfälschungen auftreten. Außerdem muss beachtet werden, dass Zählungen und Vorkommensbeobachtungen („Präsenz-Absenz-Daten“) binomiale Zufallsgrößen sind, ganz analog zum Wurf einer Münze. Die Binomialverteiltung stellt sozusagen das „Grundgesetz der Bestandserhebung“ dar und besagt, dass Zählungen (Z) erstens auch unter identischen Bedingungen automatisch streuen, und dass sie zweitens im Durchschnitt einem Anteil p der vorhandenen Bestände N entsprechen, wobei p die Antreffwahrscheinlichkeit darstellt. Drittens beinhaltet ein Vergleich zwischen zwei oder mehr Zählungen immer gleichzeitig einen Vergleich der Bestände N und der Antreffwahrscheinlichkeit p. Das bedeutet, dass ein Zeittrend in Zählungen zustande kommen kann durch einen realen Bestandstrend, durch einen Trend in der Antreffwahrscheinlichkeit oder durch eine Kombination von beidem. Eine direkte Interpretation von Zählungen impliziert immer die Annahme, dass p = 1 oder dass p konstant sei. Es ist nützlich, sich die Entstehung von Vogelzählungen hierarchisch, d. H. mehrstufig vorzustellen: In einem ersten Schritt entstehen die wahren Bestände und im zweiten die Zählungen in Abhängigkeit der Bestände und der Antreffwahrscheinlichkeit p. Extrainformation ist nötig, um die wahren Bestände korrigiert für p zu schätzen. Diese Extrainformation besteht in der Regel aus Distanzinformation oder aus wiederholten Beobachtungen, woraus Distance-Sampling- und Fangwiederfang- Methoden die echten Bestände oder das wahre Vorkommen zu schätzen vermögen. In den vergangenen Jahren haben wir im Schweizer Brutvogelmonitoringprogramm MHB mehrere Analyseverfahren vom Fangwiederfang-Typ getestet und stellen diese und unsere Befunde zusammenfassend kurz vor. Diese Methoden korrigieren für den binomialen „Beobachtungsfehler“, der allen Vogelzählungen und Vorkommensbeobachtungen inhärent ist. Wir glauben, dass man an Methoden wie den hier illustrierten eigentlich nicht vorbei kommt, wenn bei Monitoringprogrammen absolute Bestandsgrößen vonnöten sind oder wenn man für „gefährliche Muster“ in der Antreffwahrscheinlichkeit, z. B. Zeittrends in p, korrigieren möchte.Large-scale monitoring programs represent a two-level, nested sampling scheme: first, a spatial sample of quadrats or other study sites is selected, within which a second sample, of individuals, occupied quadrats or species, is chosen. To produce meaningful numbers, a monitoring program ought to be based on a spatial probability sample, otherwise the inferences obtained may be biased with respect to the desired statistical population about which one wants to learn something. Moreover, all bird counts and detection-nondetection records (misleadingly also called “presence-absence data”) are binomial random variables, much like the flip of a coin. The binomial distribution is the theoretical basis of all animal or plant surveys and explains and predicts all of their most salient features: 1. repeated counts C vary automatically, even under identical conditions; 2. on average, a count amounts to a proportion p of true population size N , where p is the detection probability, and 3. any comparison between two or more counts represents the simultaneous comparison of the associated true population size N and of the detection probability p. For instance, a temporal trend in counts may be due to a genuine trend in the underlying population size or to a trend in detection probability or to a combination of the two. Any direct interpretation of counts always implies one of two assumptions, either that of p = 1 or that of p < 1 constant. It is useful to think about the genesis of bird counts in a hierarchical way. In a first random process, the true population sizes are generated. In a second random process, the actual counts are generated conditional on these true population sizes and on detection probability. For inference about the underlying true population size free from distorting effects of the observation process, extra information is required, which usually comes as distance information or as repeated observation of a system within a period of closure. Then, distance sampling and capturerecapture methods can be used to estimate true population size or true distributions, corrected for imperfect detection. During the past few years, we have used data from the Swiss breeding bird survey MHB to experiment with, adapt and develop several such methods of the capture-recapture type. Here, we review these briefly, describe some of our key findings and provide pointers to more specific work. These methods correct counts and detection-nondetection data for the binomial observation error inherent in all bird observations. We believe that use of these methods is hard to avoid in a monitoring program if absolute population size or the absolute extent of distributional ranges, corrected for imperfect detection, are required, or if one needs to correct for “dangerous patterns” in detection probability, for instance time trends in p

Habitat structure versus food abundance: the importance of sparse vegetation for the common redstart Phoenicurus phoenicurus

As many other birds breeding in agricultural areas, the common redstart declined strongly in many Central European countries over the last 60years. The destruction of traditionally managed orchards, an important breeding habitat in Central Europe, is a relevant cause. An additional factor for the decline of this species could be the intensified management of the ground vegetation in orchards through reducing food availability and lowering prey detectability and accessibility. In this study we examined the importance of surfaces with sparse vegetation for the location of redstart territories and for foraging. To validate the results of these field studies we made habitat-choice experiments in aviaries with captive birds. Territories occupied by redstarts in orchards of northwestern Switzerland contained a significantly higher proportion of surfaces with sparse vegetation than unoccupied control sites. Redstarts made almost five times more hunting flights into experimentally established ruderal vegetation strips than into adjacent unmown meadows. No difference was observed when the meadow was freshly mown. Vegetation height and the proportion of open ground surface correctly predicted the vegetation type for hunting in 77% of the cases. Experiments in aviaries offering two types of sparse vegetation and a dense meadow supported the results of the field experiments. Even a four-fold increase of the food abundance in the meadow did not lead to a noticeable change in preference for the sparse vegetation types. For the conservation of the common redstart, not only traditionally managed orchards with tall trees with cavities should be preserved but also areas with sparse vegetation should be favore

The Multifaceted Functions of Autophagy in Breast Cancer Development and Treatment.

Macroautophagy (herein referred to as autophagy) is a complex catabolic process characterized by the formation of double-membrane vesicles called autophagosomes. During this process, autophagosomes engulf and deliver their intracellular content to lysosomes, where they are degraded by hydrolytic enzymes. Thereby, autophagy provides energy and building blocks to maintain cellular homeostasis and represents a dynamic recycling mechanism. Importantly, the clearance of damaged organelles and aggregated molecules by autophagy in normal cells contributes to cancer prevention. Therefore, the dysfunction of autophagy has a major impact on the cell fate and can contribute to tumorigenesis. Breast cancer is the most common cancer in women and has the highest mortality rate among all cancers in women worldwide. Breast cancer patients often have a good short-term prognosis, but long-term survivors often experience aggressive recurrence. This phenomenon might be explained by the high heterogeneity of breast cancer tumors rendering mammary tumors difficult to target. This review focuses on the mechanisms of autophagy during breast carcinogenesis and sheds light on the role of autophagy in the traits of aggressive breast cancer cells such as migration, invasion, and therapeutic resistance

Patches of Bare Ground as a Staple Commodity for Declining Ground-Foraging Insectivorous Farmland Birds

Conceived to combat widescale biodiversity erosion in farmland, agri-environment schemes have largely failed to deliver their promises despite massive financial support. While several common species have shown to react positively to existing measures, rare species have continued to decline in most European countries. Of particular concern is the status of insectivorous farmland birds that forage on the ground. We modelled the foraging habitat preferences of four declining insectivorous bird species (hoopoe, wryneck, woodlark, common redstart) inhabiting fruit tree plantations, orchards and vineyards. All species preferred foraging in habitat mosaics consisting of patches of grass and bare ground, with an optimal, species-specific bare ground coverage of 30–70% at the foraging patch scale. In the study areas, birds thrived in intensively cultivated farmland where such ground vegetation mosaics existed. Not promoted by conventional agri-environment schemes until now, patches of bare ground should be implemented throughout grassland in order to prevent further decline of insectivorous farmland birds

Creative Use of Mountain Biodiversity Databases: The Kazbegi Research Agenda of GMBA-DIVERSITAS

Geo-referenced archive databases on mountain organisms are very promising tools for achieving a better understanding of mountain biodiversity and predicting its changes. The Global Mountain Biodiversity Assessment (GMBA) of DIVERSITAS, in cooperation with the Global Biodiversity Information Facility, encourages a global effort to mine biodiversity databases on mountain organisms. The wide range of climatic conditions and topographies across the world's mountains offers an unparalleled opportunity for developing and testing biodiversity theory. The power of openly accessible, interconnected electronic databases for scientific biodiversity research, which by far exceeds the original intent of archiving for mainly taxonomic purposes, has been illustrated. There is an urgent need to increase the amount and quality of geo-referenced data on mountain biodiversity provided online, in order to meet the challenges of global change in mountains

Aufzuchtshabitate für Auerhühner : ein Experiment mit Haushuhnküken

Capercaillie (Tetrao urogallus) populations in Switzerland declined seriously in the past decades. The national capercaillie action plan defines actions to improve forest structure and composition in order to further the populations of the largest grouse species. These habitat measures should focus on improving summer habitat for hens with chicks, because winter habitats are available in good quality and quantity. However, our knowledge on reproduction habitats in alpine conditions is limited. In this study, we investigated microclimatic conditions, i.e. plant wetness, and movement ability of barn fowl chicks in seven characteristic field layer types in the northern Swiss Lower Alps. In the experiment on movement ability, we worked with barn fowl instead of capercaillie chicks for methodological reasons. In the bilberry-dominated vegetation, we measured a significantly lower quantity of water than in the vegetation types without bilberry. In the movement experiment, we found no significant differences between the vegetation types. As a qualitative result, we observed that the chicks moved easily even in high (> 30 cm) and close bilberry vegetation. Our results suggest that bilberry-dominated vegetation provides better conditions for grouse chicks than wet meadows and pastures, because less water adheres to the bilberry plants. Thus, the chicks get less wet in bilberry vegetation, which probably has a positive influence on the survival of the chicks. Even tall and dense vegetation seems not to impede the movement of the chicks. The results of our experiment may not be directly transferable to the demands of capercaillie chicks. Nevertheless, our study provides further evidence for the importance of bilberry as capercaillie chick habitat, especially in regions with high precipitations

Habitat structure versus food abundance : the importance of sparse vegetation for the common redstart Phoenicurus phoenicurus

As many other birds breeding in agricultural areas, the common redstart declined strongly in many Central European countries over the last 60 years. The destruction of traditionally managed orchards, an important breeding habitat in Central Europe, is a relevant cause. An additional factor for the decline of this species could be the intensified management of the ground vegetation in orchards through reducing food availability and lowering prey detectability and accessibility. In this study we examined the importance of surfaces with sparse vegetation for the location of redstart territories and for foraging. To validate the results of these field studies we made habitat-choice experiments in aviaries with captive birds. Territories occupied by redstarts in orchards of northwestern Switzerland contained a significantly higher proportion of surfaces with sparse vegetation than unoccupied control sites. Redstarts made almost five times more hunting flights into experimentally established ruderal vegetation strips than into adjacent unmown meadows. No difference was observed when the meadow was freshly mown. Vegetation height and the proportion of open ground surface correctly predicted the vegetation type for hunting in 77% of the cases. Experiments in aviaries offering two types of sparse vegetation and a dense meadow supported the results of the field experiments. Even a four-fold increase of the food abundance in the meadow did not lead to a noticeable change in preference for the sparse vegetation types. For the conservation of the common redstart, not only traditionally managed orchards with tall trees with cavities should be preserved but also areas with sparse vegetation should be favore