Modeling marbled murrelet (Brachyramphus marmoratus) habitat using LiDAR-derived canopy data

2014 ◽  
Vol 38 (2) ◽  
pp. 237-249 ◽  
Author(s):  
Joan C. Hagar ◽  
Bianca N. I. Eskelson ◽  
Patricia K. Haggerty ◽  
S. Kim Nelson ◽  
David G. Vesely

Author(s):  
John F. Piatt ◽  
K.J. Kuletz ◽  
A.E. Burger ◽  
Scott A. Hatch ◽  
Vicki L. Friesen ◽  
...  






2011 ◽  
Vol 89 (9) ◽  
pp. 859-868 ◽  
Author(s):  
Michael H. Janssen ◽  
Peter Arcese ◽  
T. Kurt Kyser ◽  
Douglas F. Bertram ◽  
D. Ryan Norris

Identifying factors that influence growth throughout development is important for understanding the consequences of variation in resource quality on recruitment. Marbled Murrelets ( Brachyramphus marmoratus (J.F. Gmelin, 1789)) are threatened seabirds that are extremely cryptic in their nesting behaviour, which makes it challenging to understand how juveniles allocate resources during development. From a single capture at sea, we analyzed stable carbon isotopes in feathers and blood of juvenile murrelets to infer diet composition during both the pre- and the post-fledging periods. Consistent with the challenges juveniles face during their first year of life, we found that wing and bill growth were prioritized in the nest, whereas development of energy stores was delayed until after nest departure. We also found that diet quality after nest departure influenced bill size and body condition, two body components that continue to grow after independence. Our results provide evidence that murrelets strategically allocate resources according to their stage of development and that the availability of high-quality prey is likely to be important to juvenile development. These results identify a potential mechanism through which feeding conditions may influence reproduction of murrelets and demonstrate the utility of stable isotopes to examine the influence of diet quality on growth over multiple stages of development.



2006 ◽  
Vol 6 (1) ◽  
pp. 241-244 ◽  
Author(s):  
MARY BETH REW ◽  
M. ZACHARIAH PEERY ◽  
STEVEN R. BEISSINGER ◽  
MARTINE BERUBE ◽  
JEFFREY D. LOZIER ◽  
...  


The Condor ◽  
2000 ◽  
Vol 102 (4) ◽  
pp. 915-920
Author(s):  
Alan E. Burger ◽  
Volker Bahn ◽  
Angeline R. M. Tillmanns

Abstract Much of the protected habitat available to the threatened Marbled Murrelet Brachyramphus marmoratus and other old-growth associated species in the Pacific Northwest is in narrow strips along the coast (e.g., parks and scenic fringes). Using data over two years from three watersheds on southwest Vancouver Island, we show that such shoreline strip forests represent suboptimal habitat for murrelets. Murrelet detections, including circling and subcanopy behaviors, were significantly lower at 30 coastal stations (20–250 m from the shoreline edge) than at 30 interior stations (1.5–21.0 km inland). Densities of predators were significantly higher at the coastal stations. The coastal trees were of similar mean height and diameter, but they had lower structural diversity and provided fewer and less suitable (thinner epiphyte cover on large boughs) nesting platforms than trees in the interior. When possible, reserves for Marbled Murrelets should be placed in interior and not shoreline forests.



The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 224-240 ◽  
Author(s):  
M. Zachariah Peery ◽  
Benjamin H. Becker ◽  
Steven R. Beissinger

Abstract The ratio of hatch-year (HY) to after-hatch-year (AHY) individuals (HY:AHY ratio) can be a valuable metric for estimating avian productivity because it does not require monitoring individual breeding sites and can often be estimated across large geographic and temporal scales. However, rigorous estimation of age ratios requires that both young and adult age classes are sampled in an unbiased manner, an assumption that is rarely tested. We estimated HY:AHY ratios for Marbled Murrelets (Brachyramphus marmoratus), a threatened seabird, using at-sea surveys and captures to assess whether age-specific differences in behavior and distribution result in biased productivity estimates in central California. AHY and HY Marbled Murrelets were distributed similarly at sea, and HY individuals did not congregate in nursery areas. Moreover, dispersal by radiomarked AHY Marbled Murrelets out of our survey area occurred at a low rate, and AHY densities were constant over the survey period, which suggests that AHY immigration and emigration did not significantly bias productivity estimates. HY density increased linearly over the survey period as expected if little dispersal occurred, which suggests that productivity estimates were not significantly biased by HY dispersal. Finally, simulation analyses indicated that annual variation in the timing of breeding resulted in only small biases in HY:AHY ratios. HY:AHY ratios were corrected for the proportion of AHY Marbled Murrelets that were incubating and the proportion of HY individuals that had not fledged at the time of sampling. Mean corrected HY:AHY ratios were low on the basis of both at-sea surveys conducted from 1996 to 2003 (0.032; SE = 0.011) and captures conducted from 1999 to 2003 (0.037; SE = 0.028), implying that productivity was poor in central California. Estimating age ratios may be an effective way of monitoring changes in reproductive success and identifying environmental factors that affect Marbled Murrelet populations, though tests of assumptions are needed in other regions. Le Rapport des Âges comme Estimateur de la Productivité: Tester les Hypothèses avec un Oiseau de Mer Menacé, Brachyramphus marmoratus







Sign in / Sign up

Export Citation Format

Share Document