encounter rates
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2022 ◽  
Author(s):  
Xia Lee ◽  
Colin Wong ◽  
Joel Coats ◽  
Susan M Paskewitz

Three compounds derived from botanicals sources, ethyl perillyl carbonate, geranyl isovalerate, and citronellyl cyclobutane carboxylate, were tested for repellent activity against Ixodes scapularis Say in a semi-field trial. Tick drags were treated with the compounds or with N, N-diethyl-m-toluamide (DEET) at high (0.25mg/cm2) or low (0.15mg/cm2) concentrations. Negative controls included untreated drags and drags treated with acetone, the carrier for all repellents. Freshly treated drags (within 20 minutes) were used to collect I. scapularis ticks at a county park in Wisconsin. To assess effectiveness, we measured tick encounter rates, detachment rate, and time to detachment. None of the repellent treatments resulted in significantly fewer encounters compared to both control treatments. However, the percentage of ticks that detached within 3 min was significantly higher on drags treated with repellents compared to controls. DEET was the most effective, repelling 69.7 - 87% of ticks by 3 min, but the effectiveness of the three test compounds was still high, ranging from 42% to 87% of ticks detaching by 3 min. For time to detachment, there were no significant differences between DEET and the three test compounds. We conclude that these botanically-derived repellents were effective against I. scapularis in a semi-field trial and could be viable alternatives to DEET.


REPORTS ◽  
2021 ◽  
Vol 6 (340) ◽  
pp. 94-105
Author(s):  
M.V. Ishchenko ◽  
M.O. Sobolenko ◽  
M.T. Kalambay ◽  
B.T. Shukirgaliyev ◽  
P.P. Berczik

2021 ◽  
Vol 2 ◽  
Author(s):  
Nicolás Gálvez ◽  
Freya A. V. St. John ◽  
Zoe G. Davies

Predators inhabiting human-dominated landscapes are vulnerable to various anthropogenic actions, including people killing them. We assess potential drivers of predator killing in an agricultural landscape in southern Chile, and discuss the implications for policies and interventions to promote coexistence. We evaluate five different types of motivation: (i) sociodemographics and household economy; (ii) livestock loss; (iii) predator encounter rates; (iv) knowledge of legal protection (all native predators are currently protected); and, (v) tolerance to livestock predation. As the killing of native predators is illegal, the prevalence of this behavior by rural residents was estimated using a symmetrical forced-response randomized response technique (RRT), a method designed to ask sensitive questions. A total of 233 rural residents from randomly assigned sample units (4 km2) across the study region completed our questionnaire. More conspicuous species, such as hawks (Falconiformes sp), foxes (Lycalopex sp) and free-roaming domestic dogs (Canis lupus familiaris), were killed by a higher proportion of farmers than more cryptic species, like the felid güiña (Leopardus guigna), skunk (Conepatus chinga) and pumas (Puma concolor). The proportion of respondents admitting to killing predators was highest for hawks (mean = 0.46, SE = 0.08), foxes (mean = 0.29, SE = 0.08) and dogs (mean = 0.30, SE = 0.08) and lowest for güiña (mean = 0.10, SE = 0.09), which is the only species of conservation concern we examine (considered Vulnerable on the IUCN Red List). From our five motivation categories, past killing of predators was associated with higher reported predator encounter rates (guina, hawks), lower tolerance to livestock predation (hawks, dogs), higher reported livestock loss (dogs) and sociodemographics and household economy (foxes). Our results demonstrate that a one-size-fits-all approach to predator persecution is unlikely to reduce or eliminate illegal killings for the suite of species we examined. We identify and describe two main types of intervention that could foster coexistence, improvement of livestock management and domestic dog management in rural areas, as well as discussing the potential for social marketing.


2021 ◽  
Vol 8 ◽  
Author(s):  
Vanessa J. Mintzer ◽  
Kristi L. Fazioli

Bottlenose dolphins (Tursiops truncatus) that inhabit urban estuaries like Galveston Bay, Texas, are exposed to cumulative stressors including pollution, fisheries, shipping, freshwater inflows, and construction operations. With continuing development, it is imperative to understand the key environmental variables that make the Galveston Bay estuary suitable habitat for this protected species. The Galveston Bay Dolphin Research Program conducted monthly photo identification surveys of bottlenose dolphins in a previously understudied 186 km2 area in upper Galveston Bay (UGB). To understand occurrence patterns in this region, we calculated monthly encounter rates of dolphins (dolphins/km) for four consecutive years (2016–2019). Using multiple linear regression models, we investigated the relationship between encounter rates, and water temperature and salinity. Monthly encounter rates ranged from 0.00 to 1.23 dolphins/km with an average of 0.34 dolphins/km (SE = 0.05). Over 80% of the variance was explained by the predictor variables water temperature and salinity (R2 = 0.820). Water temperature had a positive linear effect on encounter rates at over 23.37°C (SE = 1.42). Accordingly, higher encounter rates occurred during months with warm temperatures (May–September) compared to cooler months (November–April), indicating a predictable yearly movement pattern. Moreover, salinity was a highly significant predictor variable, with encounter rates dropping linearly with decreases in salinity. Higher numbers of dolphins are found in UGB during summer, but an exodus of dolphins occurs with low salinity levels, regardless of the time of year and water temperature. These findings should be considered during infrastructure projects (i.e., flood gate system) that may alter dolphin habitat and prey availability.


2021 ◽  
Vol 22 (9) ◽  
Author(s):  
Selsa Artika Ayujawi ◽  
Nurul Laksmi Winarni ◽  
Dimas Haryo Pradana

Abstract. Ayujawi SA, Winarni NL, Pradana DH. 2021. Short Communication: Bird correlations with waste in Muara Gembong, West Java, Indonesia. Biodiversitas 22: 3872-3879. The existence of waste in Muara Gembong can potentially affect bird abundance because organic waste can be a source of bird food, while inorganic waste can cause changes in habitat structure. This study aimed to (i) determine bird species that have a high abundance near the trash, and (ii) determine the correlation between waste concentration and the relative abundance of birds. The study was conducted in June 2020 in Pantai Mekar and Muara Blacan areas, Muara Gembong, West Java. Bird observation was carried out using exploration method and the relative abundance of the bird was determined based on encounter rates. The data collection and calculation of waste concentration were carried out following the NOAA protocol. The Spearman correlation test was carried out between the abundance of each bird species and the concentration of waste. Our results suggested that 26 species of birds in Muara Gembong were found near trash and 24 species have negative correlations to inorganic waste. The Javan munia (Lonchura leucogastroides) and Great egret (Egretta alba) were the most abundant species living near the trash with encounter rates of 39.13 and 38.89, respectively. Moreover, the concentration of inorganic waste has a significant negative correlation to the relative abundance of Cerulean kingfisher (Alcedo coerulescens), Spotted dove (Streptopelia chinensis), and Sunda collared dove (Streptopelia bitorquata). Based on these findings, inorganic waste in Muara Gembong can significantly reduce the abundance of birds in the long term because the pile of inorganic waste may cause damage to the mangrove forest, which is a bird habitat.


2021 ◽  
Author(s):  
Anna I Spiers ◽  
J Andrew Royle ◽  
Christa L Torrens ◽  
Maxwell B Joseph

1. Large-scale, long-term biodiversity monitoring is essential to meeting conservation and land management goals and identifying threats to biodiversity. However, multispecies surveys are prone to various types of observation error, including false positive/negative detection, and misclassification, where a species is encountered but its species identity is not correctly identified. Previous methods assume an imperfect classifier produces species-level classifications, but in practice, particularly with human observers, we may end up with extraspecific classifications including "unknown", morphospecies designations, and taxonomic identifications coarser than species. Disregarding these types of species misclassification in biodiversity monitoring datasets can bias estimates of ecologically important quantities such as demographic rates, occurrence, and species richness. 2. Here we develop an occupancy model that accounts for species non-detection and misclassification. Our framework accommodates extinction and colonization dynamics, allows for additional uncertain 'morphospecies' designations in the imperfect species classifications, and makes use of individual specimen with known species identities in a semi-supervised setting. We compare the performance of our joint classification-occupancy model to a reduced classification model that discards information about occupancy and encounter rate on a withheld test set. We illustrate our model with an empirical case study of the carabid beetle (Carabidae) community at the National Ecological Observatory Network Niwot Ridge Mountain Research Station, west of Boulder, CO, USA, and quantify taxonomist identification error by accounting for classification probabilities. 3. Species occupancy varied through time and across sites and species. The model yielded high probabilities (30 to 92\% medians) of classification where the imperfect classifier matched the true species. The classification model informed by occupancy and encounter rates outperformed the classification that was not, and these differences were most pronounced for abundant species. 4. Our probabilistic framework can be applied to datasets with imperfect species detection and classification. This model can identify commonly misclassified species, helping biodiversity monitoring organizations systematically prioritize which samples need validation by an expert. Our Bayesian approach propagates classification uncertainty to offer an alternative to making conservation decisions based on point estimates


2020 ◽  
pp. 68-74
Author(s):  
O. Savenko ◽  
◽  

Antarctic Peninsula region is experiencing one of the fastest rates of climate change on Earth. Its waters are known as important feeding grounds for the Antarctic minke whales (Balaenoptera bonaerensis). The purpose of the present study was to reveal the summer and early autumn presence of the Antarctic minke whales in the area adjacent to the Kiev Peninsula of West Antarctica and to estimate the encounter rates of the species in the area. The boat-based photo-identification cetacean studies were initiated as part of the long-term monitoring program based at the Akademik Vernadsky station near the Kiev Peninsula of West Antarctica. From 22 January to 7 April 2019, 35 boat and yacht cruises of the 821 nautical miles of total length were conducted. There were encountered 13 Antarctic minke whales in 7 sightings. The encounter rate was 0.015 whales per nautical mile. Minke whales were encountered only in 5% of the total sightings. Three more whales were opportunistically seen from the top of Galindez Island. There were single whales sighted and small groups of up to 3 specimens (Med = 2). At least 2 individuals were identified as juveniles. Primary behavior for whales in 7 sightings was foraging, and 2 groups were observed while travelling. A total 9 individuals of the Antarctic minke whales were photo-identified during the survey, and no matches were found between the different encounters. Our pilot study indicates summer and early autumn presence of the Antarctic minke whales in the area adjacent to the Kiev Peninsula. But encounter rates seem to be low in comparison with results of some previous surveys. Our results show the possibility to monitor minke whales in the area, and further long-term complex monitoring is essential for understanding the ecology and population dynamics of the Antarctic minke whales in rapidly changing marine environment of the Antarctic Peninsula.


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