1,721,081 research outputs found
Monitoring food provisioning and diel activity of breeding glaucous gulls (Larus hyperboreus) with nest cameras on Bjørnøya
Full text linkArctic seabirds are drawn to nutrient rich areas in the breeding season, their diet reflects the availability of prey and can function as an indicator of ecosystem status. In this study, I observed food provisioning, diel activity, environmental effects and prey delivery methods of the Glaucous gull (Larus hyperboreus) on Bjørnøya. Camera traps and time-lapse cameras were placed at the Glaucous gull’s nests at two different locations, three were placed outside large seabird colonies in 2016 (location 1) and five were placed in seabird colonies in 2020 (location 2). Prey composition for the two locations varied. Location 1 was dominated by oceanic prey, standing for 41% of prey delivered. While location 2 was dominated by avian prey, accounting for 55% of delivered prey. No diel activity pattern was observed on overall prey and avian prey, there was a 30% chance throughout the day with insignificant oscillations at 06:00 till 08:00 a.m. and 06:00 till 08:00 p.m. Diel activity pattern was observed for fish, with a slight peak in deliveries at 08:00 till 10:00 a.m. Wind and temperature had no significant effect on overall prey and fish, but did affect avian prey delivery, with a higher amount of avian prey observed in lower winds and warmer temperatures. Prey delivery method was significant, there was an 80% chance of bird prey and a 10% chance of fish prey being delivered from the crop. Little is known about food provisioning and diel activity for the Glaucous gull at Bjørnøya. The method presented shows the potential of camera traps and time-lapse cameras to monitor nesting sites, but results should be interpreted cautiously as they are based on a relatively small dataset
Contrasting body burdens of organohalogenated contaminants in two Arctic glaucous gull Larus hyperboreus populations in relation to their dietary ecology
Full text linkThis study compared body burdens of organohalogenated contaminants (OHCs) between glaucous gull populations from Bjørnøya and Kongsfjorden, Svalbard and if OHC levels was influenced by their dietary ecology and biological variables (body condition index and sex). To do so, blood from 112 adult glaucous gulls were sampled during the breeding seasons of 2015 until 2019 in Bjørnøya and Kongsfjorden. We measured plasma concentrations of OHCs including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and perfluorinated alkylated substances (PFASs). Feather stable isotopes of nitrogen (δ15N) and carbon (δ13C) were analyzed to indicate trophic level and feeding habitat, respectively. Body burdens of OHCs differed significantly between the two populations for all 5 sampling years. Overall, the population at Bjørnøya had plasma concentrations of OHCs 5.3 times higher than the Kongsfjorden population. The most quantitatively abundant contaminants found in the glaucous gulls were ΣPCBs and ΣPFASs in Bjørnøya and ∑PCBs in Kongsfjorden. No differences in relative trophic position between both breeding populations were reported although Kongsfjorden individuals varied significantly in δ15N across sampling years, while Bjørnøya individuals remained stable over time. In addition, we highlighted no relationship between plasma OHCs and feather δ15N (trophic position) although the lack of association might be due to both tissues (i.e blood and feathers) reflecting different time scales. Only ΣPFSAs and ΣPFCAs showed a positive relationship with δ13C, suggesting that feeding habitat, more than trophic position, might explain variance in contaminant exposure
Overvåkning av aktivitetsmønster og byttedyrleveringer hos lunde (Fratercula arctica) ved bruk av viltkamera
Full text linkSeabirds are top predators in the marine environment, and because seabird diet may reflect fish availability, diet may function as an indicator of fish stocks and ecosystem status. Seabird diet is traditionally studied in colonies during the breeding season, often carried out by observing adult birds returning with food loads for the chick(s), or by catching fish-carrying adults using mist-nets or noose-poles and collecting the prey. In this study, remote photography was introduced as a less invasive method of monitoring chick diet in the Atlantic puffin (Fratercula arctica) at Bjørnøya, Svalbard. Camera traps were deployed at puffin burrow entrances to record activity in the 2015 and 2016 breeding seasons. Six of the eleven breeding attempts were successful, and 160 prey load deliveries were recorded. In addition, food samples collected by the Norwegian Polar Institute (NP) at Bjørnøya were analyzed and compared with data retrieved from camera trap images. Capelin (Mallotus villosus), daubed shanny (Leptoclinus maculatus), sandeel (Ammodytes spp.) and gadids (Gadinae) were identified in the prey load deliveries recorded by camera traps. Gadids were not found in the collected samples, but Atlantic herring (Clupea harengus) was identified. Mean length of prey fish recorded by camera traps was 58.3 mm, and mean number of fish per load was 3.2. Number of fish per load decreased with increasing fish length. Fish length and number of fish per load were used to calculate prey mass and load mass. Mean load mass was 5.6 g, while mean load mass for collected samples was 6.6 g. Mean number of daily deliveries was 1.4. Compared to reported rates of delivery ranging from 5.5 to 10.3 deliveries per day at Hornøya, Finnmark, camera traps in my study recorded one out of four prey load deliveries at best. Inter-annual variance in prey load composition suggests that feeding conditions were better in 2016 than in 2015. For puffins breeding at Bjørnøya, hatching date ranged from 27 June to 10 July. No daily activity pattern in parental food provisioning was found. Prior to this study, little was known about puffin diet at Svalbard. Results should be interpreted cautiously since they are based on relatively few prey load deliveries, but the method presented demonstrates the potential of using camera traps to monitor parental food provisioning in a colonial seabird species.Sjøfugler er toppredatorer i marine økosystemer. Dietten til sjøfugl gjenspeiler tilbudet av byttedyrfisk, slik at sjøfugldiett kan fungere som en indikator på fiskebestander og tilstanden til økosystemet. Vanligvis blir sjøfuglenes diett studert i hekketida, blant annet ved å observere voksne fugler som returnerer med mat til ungen(e) eller ved å fange voksne fugler i nett eller med en såkalt fleygustong (en stang med et utspilt nett i enden) og samle inn fisken de har med seg. I dette studiet introduseres viltkamera som en ny metode for overvåkning av dietten til lunde (Fratercula arctica). Viltkameraer ble montert i inngangen til lundereir på Bjørnøya, Svalbard i hekkesesongene 2015 og 2016. Seks av elleve hekkinger var vellykkede, og totalt 160 matleveringer ble avbildet. I tillegg ble næringsprøver innsamlet av Norsk Polarinstitutt analysert for å sammenlikne med data fra viltkameraene. Byttedyrartene som ble avbildet på viltkameraene var lodde (Mallotus villosus), tverrhalet langebarn (Leptoclinus maculatus), sil (Ammodytes sp.) og torskefisk (Gadinae). Torskefisk ble ikke funnet i næringsprøvene, derimot ble det funnet sild (Clupea harengus). Gjennomsnittlig lengde på avbildet fisk var 58.3 mm, mens antall fisk per levering var 3.2. Antall fisk per levering avtok med økende lengde på byttefisk. Lengde på fisken og antall fisk per levering ble brukt til å beregne byttedyrmasse og masse per levering. For leveringer fanget på bilde var gjennomsnittlig vekt per levering 5.6 g, mens innsamlede prøver hadde gjennomsnittsvekt på 6.6 g. Gjennomsnittlig antall leveringer per dag var 1.4. Til sammenlikning varierte antall leveringer på Hornøya i Finnmark fra 5.5 til 10.3 leveringer daglig. Med Hornøya som referanse betyr dette at viltkameraene i beste fall fanget opp en av fire leveringer. Sesongvariasjon i diett tydet på en forbedring i næringstilgang fra 2015 til 2016. Klekkedato for lunden på Bjørnøya varierte fra 27. juni til 10. juli. Det ble ikke funnet noe døgnmønster i foreldrenes matleveringer. Forut for dette studiet visste man lite som lundens diett på Svalbard. På grunn av begrenset datagrunnlag bør resultatene som presenteres her tolkes med varsomhet, men metoden som er brukt demonstrerer potensialet som ligger i å bruke viltkamera ved overvåking av kolonihekkende sjøfugl.The Norwegian Environment Agency, The Research Council of Norway and Nansenfondet og de dermed forbundne fondsubmittedVersionM-N
Monitoring Daily Activity and Parental Food Provisioning in the Atlantic Puffin (Fratercula arctica) by the Use of Camera Traps
No full textSeabirds are top predators in the marine environment, and because seabird diet may reflect fish availability, diet may function as an indicator of fish stocks and ecosystem status. Seabird diet is traditionally studied in colonies during the breeding season, often carried out by observing adult birds returning with food loads for the chick(s), or by catching fish-carrying adults using mist-nets or noose-poles and collecting the prey. In this study, remote photography was introduced as a less invasive method of monitoring chick diet in the Atlantic puffin (Fratercula arctica) at Bjørnøya, Svalbard. Camera traps were deployed at puffin burrow entrances to record activity in the 2015 and 2016 breeding seasons. Six of the eleven breeding attempts were successful, and 160 prey load deliveries were recorded. In addition, food samples collected by the Norwegian Polar Institute (NP) at Bjørnøya were analyzed and compared with data retrieved from camera trap images. Capelin (Mallotus villosus), daubed shanny (Leptoclinus maculatus), sandeel (Ammodytes spp.) and gadids (Gadinae) were identified in the prey load deliveries recorded by camera traps. Gadids were not found in the collected samples, but Atlantic herring (Clupea harengus) was identified. Mean length of prey fish recorded by camera traps was 58.3 mm, and mean number of fish per load was 3.2. Number of fish per load decreased with increasing fish length. Fish length and number of fish per load were used to calculate prey mass and load mass. Mean load mass was 5.6 g, while mean load mass for collected samples was 6.6 g. Mean number of daily deliveries was 1.4. Compared to reported rates of delivery ranging from 5.5 to 10.3 deliveries per day at Hornøya, Finnmark, camera traps in my study recorded one out of four prey load deliveries at best. Inter-annual variance in prey load composition suggests that feeding conditions were better in 2016 than in 2015. For puffins breeding at Bjørnøya, hatching date ranged from 27 June to 10 July. No daily activity pattern in parental food provisioning was found. Prior to this study, little was known about puffin diet at Svalbard. Results should be interpreted cautiously since they are based on relatively few prey load deliveries, but the method presented demonstrates the potential of using camera traps to monitor parental food provisioning in a colonial seabird species
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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