35 research outputs found
First Record of Mink Frog, Rana septentrionalis, from Insular Newfoundland
Two populations of the Mink Frog (Rana septentrionalis) were identified near Corner Brook Newfoundland during wider surveys for anurans on the west coast of the island. This brings to six the number of anuran species which are known to have been introduced to insular Newfoundland, with four known to be currently extant
Fine spatial-scale variation in scavenger activity influences avian mortality assessments on a boreal island
Bird-window collisions are the second leading cause of human-related avian mortality for songbirds in Canada. Our ability to accurately estimate the number of fatalities caused by window collisions is affected by several biases, including the removal of carcasses by scavengers prior to those carcasses being detected during surveys. We investigated the role of scavenger behavior in modifying perceived carcass removal rate while describing habitat-specific differences for the scavengers present in a relatively scavenger-depauperate island ecosystem. We used motion activated cameras to monitor the fate of hatchling chicken carcasses placed at building (under both windows and windowless walls) and forest (open and closed canopy) sites in western Newfoundland, Canada. We recorded the identity of scavengers, timing of events, and frequency of repeat scavenging at sites. Using 2 treatments, we also assessed how scavenging varied with 2 levels of carcass availability (daily versus every third day). Scavenger activities differed substantially between forest and building sites. Only common ravens (Corvus corax) removed carcasses at building sites, with 25 of 26 removals occurring under windows. Burying beetles (Nicrophorus spp.) dominated scavenging at forest sites (14 of 18 removals), completely removing carcasses from sight in under 24 hours. Availability had no effect on removal rate. These findings suggest that ravens look for carcasses near building windows, where bird-window collision fatalities create predictable food sources, but that this learning preceded the study. Such behavior resulted in highly heterogeneous scavenging rates at fine spatial scales indicating the need for careful consideration of carcass and camera placement when monitoring scavenger activity. Our observations of burying beetle activity indicate that future studies investigating bird collision mortality near forested habitats and with infrequent surveys, should consider local invertebrate community composition during survey design. The high incidence of invertebrate scavenging may compensate for the reduced vertebrate scavenger community of insular Newfoundland
First Record of Mink Frog, Rana septentrionalis, from Insular Newfoundland
Two populations of the Mink Frog (Rana septentrionalis) were identified near Corner Brook Newfoundland during wider surveys for anurans on the west coast of the island. This brings to six the number of anuran species which are known to have been introduced to insular Newfoundland, with four known to be currently extant
Comparative phylogeographic analysis suggests a shared history among eastern North American boreal forest birds
Accepted author manuscriptPhylogeographic structure within high-latitude North American birds is likely shaped by a history of isolation in refugia
during Pleistocene glaciations. Previous studies of individual species have come to diverse conclusions regarding
the number and location of likely refugia, but no studies have explicitly tested for biogeographic concordance in a
comparative phylogeographic framework. Here we use a hierarchical approximate Bayesian computation analysis of
mitochondrial DNA sequences from 653 individuals of 6 bird species that are currently co-distributed in the boreal
forest of North America to test for biogeographic congruence. We find support for congruent phylogeographic patterns
across species, with shallow divergence dating to the Holocene within each species. Combining genetic results with
paleodistribution modeling, we propose that these species shared a single Pleistocene refugium south of the ice sheets
in eastern North America. Additionally, we assess modern geographic genetic structure within species, focusing on
Newfoundland and disjunct high-elevation populations at the southern periphery of ranges. We find evidence for a
âperiphery effectâ in some species with significant genetic structure among peripheral populations and between
peripheral and central populations. Our results suggest that reduced gene flow among peripheral populations, rather
than discordant biogeographic histories, can explain the small differences in genetic structure and levels of genetic diversity among co-distributed boreal forest birdsYe
Movement of Juvenile Songbirds in Harvested Boreal Forest: Assessing Residency Time and Landscape Connectivity * DĂ©placements des jeunes passereaux en forĂȘt borĂ©ale amĂ©nagĂ©e : Ă©valuation du temps de passage et de la connectivitĂ© du paysage
Little is known about juvenile songbird movement in response to timber harvest, particularly in the boreal forest. If clearcut land cover facilitates movement, the availability of resources may increase. However, if clearcut land cover impedes movement, important post-fledging resources may be rendered inaccessible. Using radio telemetry, we tested the hypothesis that regenerating clearcut land cover would affect the movement of recently independent Yellow-rumped Myrtle Warblers (Dendroica coronata coronata) and Blackpoll Warblers (Dendroica striata) differently than forested land cover owing to intrinsic differences in each land-cover type or in how they are perceived. We found that both species moved extensively before migration. We also found that Blackpoll Warblers were quick to exit local areas composed of clearcut land cover and that both species were quick to exit neighborhoods composed of large proportions of clearcut land cover. However, if individuals encountered clearcut land cover when exiting the neighborhood, movement rate was slowed. Effectively, residency time decreased in clearcut neighborhoods and landscape connectivity was impeded by clearcut land cover. Our results suggest that clearcut land cover may represent low-quality habitat for both species during the post-fledging period. Further research is needed to determine if changes in movement behavior associated with landscape structure affect individual condition and higher-level ecological processes. *
Résumé
On connait peu de choses en ce qui concerne le dĂ©placement des jeunes passereaux suite Ă la rĂ©colte forestiĂšre, particuliĂšrement en forĂȘt borĂ©ale. Dans le cas oĂč un parterre de coupe Ă blanc favorise les dĂ©placements, lâaccessibilitĂ© aux ressources peut augmenter. Toutefois, si le parterre de coupe Ă blanc nuit aux dĂ©placements, des ressources importantes aprĂšs lâenvol pourraient devenir inaccessibles. Ă lâaide de la radio-tĂ©lĂ©mĂ©trie, nous avons testĂ© lâhypothĂšse selon laquelle lâeffet dâun parterre de coupe Ă blanc en rĂ©gĂ©nĂ©ration est diffĂ©rent de celui dâun couvert forestier sur le dĂ©placement de Parulines Ă croupion jaune (Dendroica coronata coronata) et de Parulines rayĂ©es (Dendroica striata) ayant tout juste acquis leur indĂ©pendance, Ă cause des diffĂ©rences intrinsĂšques relatives Ă chaque type de couvert ou de la perception quâen ont les oiseaux. Nous avons trouvĂ© que les deux espĂšces de paruline se dĂ©placent considĂ©rablement avant la migration. Nous avons Ă©galement constatĂ© que la Paruline rayĂ©e quittait rapidement les secteurs locaux constituĂ©s de parterres de coupe Ă blanc et que les deux espĂšces quittaient rapidement les secteurs voisins qui comportaient une grande proportion de parterre de coupe Ă blanc. Cependant, si un individu atteignait un parterre de coupe Ă blanc au moment de quitter le voisinage, son taux de dĂ©placement Ă©tait ralenti. Dans les faits, le temps de passage diminuait dans le voisinage des parterres de coupe Ă blanc et ces derniers rĂ©duisaient la connectivitĂ© du paysage. Nos rĂ©sultats donnent Ă penser que les parterres de coupe Ă blanc reprĂ©sentent des milieux de faible qualitĂ© pour les deux espĂšces de paruline durant la pĂ©riode qui suit lâenvol. De plus amples recherches sont nĂ©cessaires afin de dĂ©terminer si les changements au plan du comportement en dĂ©placement selon la structure du paysage ont un effet sur la condition de lâindividu et sur les processus Ă©cologiques gĂ©nĂ©raux
A tropical perspective on conserving the boreal âlung of the planet
a b s t r a c t Navjot Sodhi is best known for his advancement of tropical ecology and conservation science; however, his research origins were in fact based in the boreal forest ecosystem of Canada. Ironically, the lessstudied ecosystems of the tropics have recently received much more conservation attention than northern biomes, despite the boreal forest (i) representing about one third of all remaining forest on the planet (and about 50% of the world's remaining tracts of large, intact forest), (ii) sequestering about 30% of the Earth's stored terrestrial carbon, and (iii) becoming increasingly fragmented with ecologically contiguous patches constituting only 44% of its entire area. These heightened threats of fragmentation and increasing fire frequency associated with expanding human industry in the boreal zone, along with climate change, mean that more international focus on the plight of the boreal ecosystem is warranted. Prior to his death, Navjot Sodhi had accepted a position at the University of Toronto where he planned to apply his keen, transdisciplinary approaches to boreal conservation science in an attempt to prevent the future destruction of planet Earth's second 'lung'. Although he never realised this dream, here we provide an overview and examples of how appropriate boreal forest management can be achieved