The term 'field propagation and release' refers to the breeding of captive adults in large field enclosures, allowing them to raise their young, and then releasing those young from that location. This technique is currently being implemented in Canada as one of several recovery tools for the endangered eastern loggerhead shrike Lanius ludovicianus migrans. During 2001-2007 a total of 360 shrike fledglings were produced in field propagation enclosures and 301 were released from these enclosures. Annual return rates of birds released since 2004 are 2-6.6%. Seventeen released birds have been re-sighted, including 10 birds that have returned to the breeding grounds the following season to produce young with wild mates. The high annual return rate of release birds and the successful integration of these birds into the wild breeding population represent important milestones for the recovery of this population. The management technique we describe here has the potential to be applicable to other species that require natural habitat for breeding and/or are reliant on a suite of parent-learned behaviours that cannot be accommodated for or adequately replicated within intensive close captive-breeding or hand-rearing conditions.
. 2015. Using an integrated recording and sound analysis system to search for Kirtland's Warbler (Setophaga kirtlandii) in Ontario. Canadian Field-Naturalist 129(2): 115-120.We used automated sound recording devices and analysis software to search for Kirtland's Warbler (Setophaga kirtlandii) in northeastern Ontario. In 2012, we conducted surveys at 38 locations in three Ontario Ministry of Natural Resources administrative districts: Chapleau, Sault Ste. Marie, and Sudbury. We detected a Kirtland's Warbler at one location in Sault Ste. Marie District on a single date: June 6. We believe that the recording and analysis approach we used is an effective method for detecting Kirtland's Warbler, or other rare bird species, across extensive areas of their potential range.
BackgroundThe Loggerhead Shrike, Eastern subspecies (Lanius ludovicianus ssp.) (LOSH) is a predatory songbird native to Eastern North America. It is estimated that there are fewer than 55 breeding pairs of this subspecies in North America. Captive breeding plays a critical role in preventing the extirpation of this subspecies from its Canadian range. Unfortunately, high numbers of unexplained deaths among young birds in the captive breeding population threatened the success of this program. This paper describes fledgling mortality in the captive breeding population, and seeks to identify factors associated with fledgling survival and, ultimately, to identify steps to mitigate fledgling mortality.ResultsOver the study period (2006–2011) at two breeding sites, 696 LOSH were fledged. Among these, 68 % (n = 474) were released, 10 % (n = 69) were retained in the captive breeding population, and 22 % (n = 155) died. Fledgling survival declined from 99 % in 2006 to 44 % in 2011. The odds of survival were significantly lower for fledglings that were part of a second clutch. As the number of fledglings in a clutch increased, the odds of surviving increased significantly. As the breeding female aged from one to four years of age, there was a marked increase in the odds of a fledgling surviving, which then subsequently declined as females aged further.ConclusionsBased on our analyses, clutch number (first or second), number of fledglings in the brood, and age of breeding females were significant predictors of fledgling survival. Long-term breeding management decisions will have to balance the need to increase the number of individuals and breeding pairs in the wild by releasing large numbers of young, against the need to maintain a genetically viable captive population, until the wild population is large enough to be self-sustaining.
Worldwide, insect populations are declining, and the eastern migratory group of the monarch butterfly Danaus plexippus in North America has not escaped this fate. The conservation of this iconic species is an international priority but requires knowledge of how monarchs interact with the landscape during different stages of the annual cycle. To better understand habitat needs of monarchs departing their core breeding range in southern Ontario, Canada, we examined how various landscape features influenced roost site selection during fall migration—an instrumental resource link between the breeding and wintering grounds. Using dedicated fall migration surveys along the Great Lakes coastlines and a citizen science dataset collected across all of Ontario, we evaluated the relationship between roost site occupancy and 18 landscape variables using a boosted regression tree (BRT) modelling approach. Results suggest that a closer distance to the Great Lakes, increased goldenrod Solidago spp. cover, moderate forest cover, rural road cover, and urban land cover are all important to roosting site selection. Our research provides important insights into the habitat characteristics of stopover sites, which will help guide future investigations and conservation actions to preserve monarch butterflies and their migratory phenomenon.
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