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Avian reproduction and population growth are highly dependent on food availability. Consequently, studies on these variables require accurate estimates of food abundance that may vary in space and time. Dippers (Cinclus spp.) are obligate stream predators in freshwater ecosystems. Although it is well known that dippers are affected by aquatic macroinvertebrate density and proportion of riffle habitat, rarely are these two factors combined to estimate their food availability. We developed a new method to estimate food availability and tested the relationship of food availability with reproduction performance of the Brown Dipper (Cinclus pallasii) in Taiwan from 2013 to 2015. We defined three stream types (stony riffles, sandy runs, and pools) with water depth and benthic substrate. Macroinvertebrate biomass was significantly greater in stony riffles than in sandy runs. We then measured the area of the three stream types in a 400-m stream segment centering on each Brown Dipper’s nest. The area of stony riffles was multiplied by average macroinvertebrate density of each stream to represent food availability in stony riffles of each territory. Response variables on reproductive performance (e.g., laying date, clutch size, fledgling number, and territory length) of each nest were recorded. Linear mixed-effects models showed that food availability estimated using the area of stony riffles was significant correlated with all aspects of reproductive performance of Brown Dippers and was a better predictor than food availability estimated in the total water area. This study also demonstrated that summer floods and winter flows (high or low water level) could influence food availability in the dipper’s breeding season by different mechanisms.

Extreme weather events such as tropical cyclones are becoming more frequent, but efforts to understand their impact on wildlife have focused on population-level change rather than the behavioural responses of individuals. In this study, we monitored individually marked Brown Dippers Cinclus pallasii in upland Taiwanese streams in order to investigate the movements of these birds following typhoons in 2004, 2012 and 2013. Individuals moved significantly longer distances immediately after floods compared with before, and in typhoon years compared with other years. Most of these movements involved temporary displacement from a major stream to one of its tributaries, where population size and food abundance are typically lower. These results suggest that movements after flooding were not driven by food abundance but that relatively poor quality streams may provide an important refuge for birds following typhoons.

Due to climate change, extreme weather events are becoming more frequent and severe. These extreme events have been documented to affect avian predators in stream ecosystems. To better understand the mechanisms behind this effect, we used a decade-long dataset from a mountain stream in Taiwan to assess the effects of extreme flooding caused by typhoons on invertebrate abundance in different periods of the year and the resulting effects on reproductive output of an avian predator of these invertebrates, the Brown Dipper (Cinclus pallasii). In this study stream, all extreme floods occurred between June and October, and these floods negatively affected invertebrate density. Consequently, average invertebrate density was lowest in October at the end of the typhoon season, and highest 4 mo later. Because invertebrate density increases over time after a flood, the length of the recovery period between floods that occurred between June and October was more important than each flood's magnitude in determ...

Anticoagulant rodenticides (ARs) are known to cause extensive secondary exposure in top predators in Europe and North America, but there remains a paucity of data in Asia. In this study, we collected 221 liver samples from 21 raptor species in Taiwan between 2010 and 2018. Most birds were recovered from rescue organizations, but some free-ranging individuals were obtained from bird-strike prevention measures at airports. ARs were detected in 10 species and more than half of the total samples. Common rodent-eating Black-winged Kites (Elanus caeruleus) had the highest prevalence (89.2%) and highest average sum concentration (0.211 ± 0.219 mg/kg), which was similar between free-ranging birds at airports and injured birds from rescue organizations. Scavenging Black Kites (Milvus migrans) and snake-eating Crested Serpent-eagles (Spilornis cheela) had the second highest prevalence or sum concentration, respectively. Seven different AR compounds were detected, of which brodifacoum was the most common and had the highest average concentration, followed by flocoumafen and bromadiolone. The frequency of occurrence in the three most numerous species (Black-winged Kite, Crested Goshawk [Accipiter trivirgatus], and Collared Scops-owl [Otus lettia]) was significantly higher in autumn than summer, which is consistent with the timing of the Taiwanese government's supply of free ARs to farmers. Regional differences in the detection of individual compounds also tended to reflect differences in human population density and use patterns (in agriculture or urban-dominated environments). Clinical poisoning was confirmed in Black Kites with sum concentrations as low as 0.026 mg/kg; however, further study of interspecific differences in AR sensitivity and potential population effects are needed. In addition, continued monitoring remains important given the Taiwanese government has modified their farmland rodent control policy to gradually reduce free AR supplies since 2015.

Capsule Molecular scatology can characterize predator diets by the identification of mixed and degraded prey fragments in predator faeces.Aims We evaluated whether a non-invasive, molecular technique was useful for identifying prey in the faecal samples of the Plumbeous Water Redstart Phoenicurus fuliginosa, which feeds in the riparian ecotone and, therefore, depends on prey from both terrestrial and aquatic sources.Methods Samples of intact faeces were collected in the riparian zone during 2010 to 2012 in Taiwan. A Bayesian model was used to delimit distinct species based on the phylogenetic species concept. Prey identities were determined using the Barcode of Life Data system.Results We examined 283 faecal samples and detected DNA in 190 using DNA barcodes. We identified 505 prey DNA sequences belonging to 108 distinct species. Beetles were detected in more samples (64 of 190) than any other taxon, and aquatic insects were found in 100 of 190 samples.Conclusion This molecular approach for identifying pr...

The survival of rare animals is an important concern in an environmental impact assessment. However, it is very difficult to quantitatively predict the possible effect that a development project has on rare animals, and there is a heavy reliance on expert knowledge and judgment. In order to improve the credibility of expert judgment, this study uses Bayesian belief networks (BBN) to visually represent expert knowledge and to clearly explain the inference process. For the case study, the primary difficulty is in determining a large amount of conditional probabilities in the BBN, because there is a lack of sufficient data concerning rare animals. Therefore, a new method that uses fuzzy logic to systematically generate these probabilities is proposed. The combination of the BBN and the fuzzy logic system is used to assess the possible future population status of the Pheasant-tailed jacana and the associated probabilities, which have been affected by the construction of the Taiwan High-Speed Rail. The analysis shows that a restoration program would successfully preserve the species, because in the restoration area, the BBN model predicts that there is a 75.49 % probability that the species will flourish in the future.

Dam removal is an approach for restoring rivers. However, there are increasing concerns about the impact of removal on downstream biota. We examined the short-term responses of benthic macroinvertebrates and their avian predator (Brown Dipper, Cinclus pallasii Temminck) in reaches downstream of a check dam after it was removed from a mountain stream in central Taiwan. The density and taxonomic richness of downstream macroinvertebrates decreased immediately after dam removal. The decreases were associated with scouring or burial by sediments from the upstream impoundment. Ten weeks post-removal, downstream macroinvertebrate densities, although marginally recovering, remained lower than both pre-removal and upstream densities. Substantial changes in community structure were not significantly associated with an increase in the proportion of taxa with short life spans. However, this small-scale disturbance had no strong effect on the abundance of their very mobile, avian predator. This study and other studies of dam removal have found that downstream sedimentation following dam removal can reduce macroinvertebrate densities and that they may recover over time. Thus, timescale must be considered when interpreting the consequences of dam removal, especially when the long-term goal is stream restoration.

The predicted effects of global climate change include altered patterns of precipitation and more extreme weather events, leading to an increase in the severity and frequency of episodic disturbances such as floods. These changes may affect lotic prey communities, which could indirectly affect aquatic and riparian predators through trophic linkages. We assessed whether extreme flooding affected the apparent survival of Brown Dippers Cinclus pallasii in Taiwan using mark–resighting data and climate data. The probability of survival was negatively correlated with the degree of flooding, and survival of first-year birds was lower than that of adults. Previous analyses of this system suggest that the main, indirect mechanism driving such patterns is the impact of flood disturbance on the aquatic invertebrate prey of Brown Dippers. Our results show that changes in prey communities induced by flooding have the potential to affect predators in aquatic and adjacent riparian habitats. This highlights the importance of considering cross-ecosystem linkages when identifying conservation and management goals in the face of future climate uncertainty.

Using the Ecopath approach and a network analysis, a mass-balance trophic model was constructed to analyze the structure and energy flows of a high-altitude subtropical headwa- ter stream, Chichiawan Stream, the only habitat of the Critically Endangered Formosan land- locked salmon Oncorhynchus formosanus. Natural abundances of carbon and nitrogen isotopes (δ 13 C and δ 15 N) were used as a complementary method to stomach content analysis to trace food sources of consumers in the stream. Riparian C3 plants were the major food source of dominant gatherer and filterer aquatic insects, while diatoms were the major food source of scraper aquatic insects. Lindeman trophic analysis indicated that the flows of detritivory and herbivory were quantitatively equally important as food sources for consumers in the stream, suggesting a close terrestrialaquatic linkage. The trophic model of Chichiawan Stream comprised 13 compartments and 4 integer trophic levels with the highest trophic level of 3.12 for birds. The pedigree index for the trophic model was 0.71, indicating a high-quality model. The mixed trophic impacts indicated that the biomass of Formosan salmon was unlikely constrained by food sources or predation pres- sure by birds. In a comparative analysis with other trophic models of temperate mountain streams, the total consumer biomass and mean trophic transfer efficiency were relatively low in this sub- tropical mountain stream, which is characterized by high precipitation, steep channels, rapid cur- rent velocity, and changing flow regime. To conserve the Formosan salmon, the first priorities are agricultural runoff control and maintaining a well-vegetated riparian zone.

Sound management of the Mandarin Duck (Aix galericulata) requires an understanding of its survival and cause-specific mortality, yet these parameters have not been studied in Taiwan. From January 1999 to December 2002, a study was conducted along the Tachia River, in central Taiwan, where the largest population of Mandarin ducks resides. The sex ratio was male-biased for adults (average 2.10:1) but not for juveniles (average 0.92:1). Ducks (34 males and 42 females) were radio-tagged and monitored two to three times per month for 1–47 months. Annual survivorship was 0.80 and 0.44 for male and female ducks, respectively; lower female survival may lead to a male-biased sex ratio. Forty-three ducks died, the greatest proportion from unknown causes, followed by avian predators, mammalian predators and anthropogenic activity. Mortality occurred year-round, but female mortality was greatest from spring to fall, 9–10 carcasses, while male mortality (seven) was greatest in the winter.

The Black Kite (Milvus migrans) has a limited distribution within Taiwan due to a dramatic population decrease during the late 20th century. Prompted by some poisoning incidents of Black Kites and other farmland birds, we hypothesized that poisoning may be an underreported yet important threat. Thus, we created a citizen-science Facebook group in October 2014 in order to receive more information about possible poisoning incidents. By September 2016, we had received reports of 4753 dead birds in 213 separate poisoning incidents in agricultural areas. The types of fields most often associated with poisoning incidents were direct-seeded rice (Oryza sativa), rice that was soon to be harvested, and red beans (Vigna angularis). We tested tissues from 29 dead small birds for pesticide residues. Twenty-eight birds contained carbofuran, and one bird contained terbufos, both highly toxic pesticides. Furthermore, of seven dead Black Kites tested from 2010 to 2016, four contained carbofuran, and three contained second-generation anticoagulant rodenticides. After interviewing farmers and reviewing older agricultural literature, we concluded that most of these incidents represented intentional poisonings by farmers attempting to control avian pests and rats (mostly Bandicota indica and Rattus spp.). We suggest that the Black Kites were likely the victims of inadvertent secondary poisoning incidents. The dramatic decrease of the Black Kite in the 1980s coincided with the rapid increase in the area planted with direct-seeded rice and the widespread use of carbofuran and rodenticides. The recent decreased use of these pesticides due to restrictions has coincided with the recent slow recovery of the Black Kite population. Therefore we initiated public awareness campaigns, and the Taiwanese government has adjusted some pesticide-use policies.

Little is known about the abundance and distribution of Chinese Goshawks (Accipiter soloensis) during spring migration along the Western Pacific flyway around Taiwan. This species is the most numerous migratory raptor in East Asia. In April 2004, we employed weather radar at Kenting and Chiku to study the spatial and temporal distribution and flying behavior of migrants in the Taiwan area. Goshawk flocks migrating across Luzon Strait toward Taiwan (n = 193) averaged 3.1 km in length (SD = 3.41, range 1.0–27.5 km) and 0.7 km in width (SD = 0.30, range 0.3–2.5 km). Using a regression model relating bird numbers to the reflectivity of radar images, we estimated that at least 225 935 Chinese Goshawks passed through the study area during 5 d in the month of April. Flocks crossing the Luzon Strait approached the Hengchun Peninsula, at the southern tip of Taiwan, along several inland and offshore routes, making it difficult to obtain accurate and complete observations from the ground. Farther nort...

Resumen En Taiwan, se conoce poco acerca del comportamiento reproductivo de Spizaetus nipalensis, un ave de bosques que se encuentra amenazada. Descubrimos cinco nidos entre 2005 y 2007. Entre marzo y junio de 2007, hicimos observaciones en los tres nidos activos, que estaban ubicados en montanas de elevaciones bajas en el sur de Taiwan. Los machos trajeron el 76.4% (DE: ±21.5%) de los items alimenticios a los nidos. Con base en el color del iris, inferimos que los machos de las tres parejas eran mas jovenes que sus consortes. En terminos de frecuencia, las presas llevadas a los nidos fueron mamiferos (76.1 ± 10.8%), aves (15.9 ± 8.2%) y reptiles (7.6 ± 6.1%). De forma inesperada, las ardillas voladoras nocturnas (Petaurista philippensis y P. alborufus) fueron las presas mas importantes en los tres nidos. Cuatro macacos Macaca cyclopis jovenes tambien fueron llevados a los nidos.

Summary 1. The effects of flooding on top predators are poorly understood globally, but particularly in monsoonal streams. We therefore attempted to assess how inter-annual and intra-annual variations in flood magnitude affected an obligate riverine predator, the brown dipper (Cinclus pallasii), and its invertebrate prey, in the mountain Tachia River, Taiwan. Major flooding in one of the study years (2005) allowed an insight into the effects of abnormally large flows. 2. The abundance and biomass of insects, and the abundance of dippers, decreased steadily from 2003 to 2005 as flood magnitude grew, but then increased in 2006 when more typical discharge returned. Dipper abundance, insect abundance and insect biomass were all strongly positively inter-related, but negatively related to discharge. Insect biomass, rather than abundance, was more useful in predicting brown dipper abundance. 3. Aquatic insect composition fluctuated among sampling years, revealed by non-metric multidimensional scaling, and these fluctuations were also related to discharge. In turn, dipper abundance and the mean body size of aquatic insects declined with the shift in insect composition as flow increased. 4. These data illustrate how discharge fluctuations can have pronounced effects on top predators in streams, mediated in this case by fluctuating prey abundance. While contributions from bird movement, breeding performance and mortality were not clearly differentiated, our data reveal how dippers have strategies to accommodate varying discharge in river systems. We suggest that the effects of floods on dippers should be taken into account when using this group as indicators of river quality.

We examined the diet of Tawny Fish-Owls (Ketupa flavipes) living along Sakatang Stream, Taiwan, from January 1994–July 1995 and from February 1998–January 1999. In both number and biomass, aquatic prey constituted the majority of the owls' diet. The most frequently caught prey were small freshwater crabs (Candidiopotamon spp.). Nevertheless, the Taiwan mitten crab (Eriocheir formosa) and the Taiwan common toad (Bufo bufo gargarizans) made up the largest proportion of prey biomass in different years. The breeding activity of prey species appeared to influence their representation in the owls' diet. Large and sluggish prey species such as Taiwan mitten crab and Taiwan common toad were preyed upon more frequently than expected relative to their availability.