The effects of vessel approaches on the New Zealand fur seal (Arctocepahlus forsteri) in the Bay of Plenty, New Zealand
Cowling, M. ; Kirkwood, R.J. ; Boren, L. ; Sutherland, D. ; Scarpaci, C. - \ 2015
Marine Mammal Science 31 (2015)2. - ISSN 0824-0469 - p. 501 - 519.
breeding-season - harbor seals - behavioral-responses - tourist disturbance - wildlife tourism - south-australia - vigilance - experiences - population - predation
Animals that establish new sites near the edge of the species' range may be vulnerable to disturbance as they are low in numbers and are not tied to the sites. Pinniped distributions world-wide are changing as many species are recolonizing areas of their former ranges and establishing new colonies. Little research is available on the impact that vessel presence may pose on pinnipeds at such sites. This study documents responses of New Zealand fur seals to vessels in the Bay of Plenty, New Zealand, at a recently established breeding colony. Fur seal behavior at the breeding location was recorded in the presence of vessels. GLMM and GAM analyses revealed that fur seal responses varied with month, time of day, duration of vessel exposure, and the distance to the vessel. Age and sex of the seals, and the number of seals present also influenced fur seal response. Fur seals at this site became disturbed when vessels approached to the 10–20 m distance category, and a precautionary minimum approach distance of 50 m has been suggested. This research provides direction for monitoring and minimizing impacts of vessels on fur seals, especially where new sites are being colonized.
Do field margins enrich the diet of the Eurasian Skylark Alauda arvensis on intensive farmland?
Ottens, H.J. ; Kuiper, M.W. ; Flinks, H. ; Ruijven, J. van; Siepel, H. ; Koks, B.J. ; Berendse, F. ; Snoo, G.R. de - \ 2014
Ardea 102 (2014)2. - ISSN 0373-2266 - p. 161 - 174.
false discovery rate - sown weed strips - food resources - nestling diet - agricultural intensification - bird populations - breeding-season - adjacent fields - perdix-perdix - prey quality
To help restore food availability for birds, arable field margins (extensively managed strips of land sown with grasses and forbs) have been established on European farmland. In this study we describe the effect of field margins on the diet of Eurasian Skylark nestlings and adults living on intensively managed Dutch farmland. We tested the hypotheses that field margins offer a higher diversity of invertebrate prey than intensively managed crops, and that the diet of nestlings receiving food from field margins will therefore be more diverse than that of other nestlings. Field margins had a greater variety of invertebrate prey groups to offer than the intensively managed crops. Coleoptera were the most frequently and most abundantly eaten prey group by both adults and nestlings. Together, Coleoptera, Diptera, Lepidoptera, Hymenoptera and Araneae accounted for 91% of the nestling diet. Nestlings ate larger prey items and a larger proportion of larvae than adults. Almost 75% of both adults and nestlings consumed plant material, perhaps indicating a scarcity of invertebrate resources. When provided with food from field margins, the mean number of invertebrate orders in the nestling diet increased significantly from 4.7 to 5.5 and the number of families from 4.2 to 5.8 per sample. Thus, birds that used field margins for foraging could indeed provide their young with more invertebrate prey groups than birds only foraging in crops and grassland.