Nest predation in riparian buffer strips in a balsam fir forest in Western Newfoundland

Lewis, Keith P. (1999) Nest predation in riparian buffer strips in a balsam fir forest in Western Newfoundland. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (10MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Logging pressures on boreal forests have increased in recent decades and carry with them increased concerns for wildlife and habitat conservation. Buffer strips mitigate some of the negative impacts of logging on riparian habitat and associated wildlife. Given the widespread use of buffer strips, the subsequent increase of clear-cut/forest edge, and the decline of many forest birds. I investigated how buffer strips and habitat edges influence avian nesting success. Nest predation is the most common cause of nest failure among song birds. Therefore, artificial nests are a useful research tool for investigating the influences of habitat alteration on nest predation. Japanese Quail (Coturnix japonica) eggs are often used in artificial nest studies, although these eggs may be too large to detect predation by small mammals. My primary objectives were to determine 1) if nest predation differs between intact riparian forest and a) buffer strips and b) clear-cut forest edges, and 2) if Japanese Quail eggs are appropriate to use in artificial nest studies in western Newfoundland. -- Artificial tree and ground nests (n = 150 in 1996, n = 420 in 1997) with Japanese Quail eggs were used to measure nest predation in study blocks (k = 5 in 1996, k = 7 in 1997) that included buffer strips, intact riparian forest, and clear-cut forest edges. The second experiment used artificial ground nests (n= 180) with Chinese Painted Quail (Xexcalfactoria chinensis) eggs and Japanese Quail eggs to measure the influence of egg-size on ground-nest predation in buffer strips (k = 4) and intact forest sites (k = 5). The influences of buffer strip width, nest visibility, and distance of the nest from the nearest edge on nest predation were measured and nest predators documented. -- Nest predation was significantly different and extremely variable between study sites in both experiments suggesting that local presence of predators may be influenced by site-specific conditions, rather than specific types of habitat alteration. Nest predation did not differ between intact riparian forest (55 %) and a) buffer strips (41 %) and b) clear-cut forest edge (50 %). Nest predation significantly increased with increasing buffer strip width (13-38 m). However, the conservation value of buffer strips is likely to increase with width due to low increases in predation, greater abundance of Neotropical migrants, and lower proportional windfall rates in wider buffer strips. Nest predation was higher on tree nests than on ground nest in both years, and nests with greater visibility were more successful than exposed nests. Gray Jays {Pensoreus canadensis) and red squirrels {Tamiasciurus hudsonicus) were the only identified nest predators. Gray Jays preyed significantly more on tree nests than ground nests while red squirrels preyed equally on both nest types. Egg- size did not influence predation. I conclude that predation is influenced by site- specific factors and that Japanese Quail eggs are appropriate for artificial nest studies in western Newfoundland.

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