Have you seen a Bicknell's Thrush?

Consider adding it to eBird to help us track locations.

---

Would you like to help monitor populations?

In the U.S. join Mountain BirdWatch

In Canada join the High Elevation Landbird Program

---

Breaking News

IBTCG Sponsored Symposium at American Ornithologists' Union Meeting in Philadelphia

Bicknell's Thrush in the news

 

 

 

 

 

 

 

Breaking Research News:

IBTCG Sponsors Thrush Symposium at American Ornithologists' Union Meeting in Philadelphia.Watch the presentations!

Past Research

Two pioneering Bicknell’s Thrush studies paved the way for the recent surge of research and monitoring efforts completed or underway in the northeastern U.S., Canada, and the Caribbean Greater Antilles.  George Wallace’s classic natural history study (Wallace 1939), conducted in the mid-1930s on Vermont’s Mt. Mansfield, illuminated basic facets of the (then sub)species’ taxonomy, habitat use and biology.  It remains a solid reference today.   Henri Ouellet’s careful examination of Bicknell’s and Gray-cheeked thrush in the early 1990s (Ouellet 1995) compared characteristics of plumage, morphology, vocalizations, distribution, and biochemistry.  His proposal to the AOU Checklist Committee that Bicknell’s Thrush be classified as a distinct species from Gray-cheeked Thrush was accepted, immediately heightening both awareness and concern for the conservation status of this “new” and rare species.

Research on Bicknell’s Thrush since Ouellet’s pivotal study has spanned efforts to investigate the species’ breeding and winter distribution and habitat preferences, its unique breeding ecology, its use of ski areas and industrial forests, its overwinter ecology and demography, and its ecotoxicology.  Long-term monitoring of breeding populations has been established via Mountain Birdwatch (MBW) in the U.S. and the High Elevation Landbird Program (HELP) in Maritime Canada.

Research highlights, by region, are outlined below.

Canada (Maritimes, Quebec)
Caribbean
United States (Monitoring, Research)

Canada (Maritimes, Quebec)

Maritimes (New Brunswick and Nova Scotia)

1995-2001 Canadian Wildlife Service (CWS; Dan Busby lead) surveyed the Maritimes to document locations where BITH was present and to obtain rough estimates of numbers and habitats.

1997-98 Erin Nixon was contracted to write the status report for the Committee on the Status of Endangered Wildlife in Canada. BITH was listed as “Special Concern”.

1998 Erin Nixon, working for Canadian Forestry Service, conducted point counts and transects on industrial forest land in NB.

1998 Two Honour’s theses were completed with Tony Diamond at the University of New Brunswick (UNB) by Geoff Clarke and Richard Curran (both spatial analyses of NB habitat).

1999-2001 Erin Nixon completed her Master’s degree with Tony Diamond at UNB on habitat associations in NB industrial forest.

2001 Bird Studies Canada conducted field work in Cape Breton to develop a protocol for monitoring BITH and other high elevation bird species.

2002 High Elevation Landbird Program (HELP) began. Protocol was modified in 2003 to mesh with VINS Mountain Birdwatch.

2004-05 Sarah Chisholm conducted her Master’s research with Marty Leonard of Dalhousie University on the impact of pre-commercial thinning on abundance of Bicknell’s Thrush and other high elevation birds.

2005 CWS, with Matt Mahoney, conducted some habitat modeling, based on latitude/elevation model by Lambert et al.

2006 Rob Gardiner completed Honour’s thesis with Matt Evans at Mount Allison University on the long-term effects of pre-commercial thinning on Bicknell’s Thrushes and four other high elevation songbirds in the New Brunswick highlands.

2006-2010 Fieldwork for the second Maritimes Breeding Bird Atlas underway.

2007-08 Emily McKinnon began Master’s thesis with Tony Diamond at UNB on impacts of pre-commercial thinning on breeding biology of BITH.  Kevin Fraser began PhD with Tony Diamond at UNB on how wintering habitat impacts breeding condition of BITH and SWTH.

2007 Five year analysis (2002-2007) of HELP data shows declines on the order of 19% per year in both Nova Scotia and New Brunswick, and within two distinct subregions per province as well (Poisson generalized linear model used).

back to top

Quebec

1990s In Quebec, the first person to investigate the Bicknell’s Thrush was the late Henri Ouellet who worked with Gilles Seutin to have the Bicknell’s Thrush recognized as a distinct species from Gray-cheeked Thrush. 

1999-2000 Veronique Connolly conducted her M.Sc. research with Gilles Seutin and Jean-Pierre L. Savard (CWS), focusing on habitat used during the breeding period.

1997-98 Surveys were conducted at specific sites in southern Quebec by Y. Aubry (CWS) and team. Sites visited were located in the Laurentians, in the Estrie region, and on the Gaspé Peninsula. At the same time, Charlevoix was surveyed and some birds banded.

1999 A banding and radio-telemetry project began at Mine Madeleine (Gaspésie National Park). Intensive work ended in August 2003. Researchers video-monitored activities at nests from 1999 to 2003 and recorded movements of radio-tagged birds.

1999 Melanie Ball conducted field work at Mine Madeleine for a Master’s thesis on Bicknell’s Thrush vocalizations under the supervision of Cindy Staicer, Dalhousie University.

2000 Yves Aubry started Ph.D. research at Laval University (André Desrochers, Director and Gilles Seutin, co-directors). Research topics are summarized here: 

Chapter 1: BITH habitat selection and preferences on Mont Gosford in relation to thinned (in 1996 and in 1986) and unthinned forest stands. Estimated home ranges from radio-tracking data and used compositional analysis for this chapter.

Chapter 2. What are the environmental parameters influencing BITH occurrence at the local scale: altitude, height of dominant tree stratum, Swainson’s Thrush abundance, slope, slope orientation, habitat composition, and habitat type (thinned and unthinned). Analysis from 2 regions: Gosford (129 point counts per year, 2001-2004 ) and Gaspé Peninsula. (n>400 point counts, mostly in 2005).

Chapter 3. Is there any genetic/social structure at the nest level (between feeding males and genetic fathers and between them and the mother), at sub local level (multi-nests or sub-sectors of Mount Gosford) and at regional level (Mount Gosford and Mine Madeleine).

2000-2004 Point-count surveys (129 stations; 2000-2004), banding, radio-telemetry, as well as nest video-monitoring were conducted at Mount Gosford.

2005 Extensive surveys were conducted at 389 sites throughout the Gaspé Peninsula. Sites were selected according to altitude (>600 m or <600 if within 15 km of coast) and habitat suitability (Balsam Fir as dominant or co-dominant species of forest stands). BITH was detected at 18 of the 389 sites.

2006 BITH surveys were done in an area north of Baie-Comeau, on the North shore of the St. Lawrence River. The study area was located on the edge of the Laurentian Shield, just south of the Manicougan reservoir. Of the 400 point-counts done, Bicknell’s Thrush was recorded from only 2. There are a handful of previous records originating from the North Shore of the St. Lawrence River, where Black Spruce dominates the landscape with Balsam Fir restricted to small dispersed stands.

2007 At Massif du Sud (60 km east of Quebec City), surveys were conducted at 183 sites between May 31 and June 15; 41 were occupied by BITH. This site is targeted by a wind-power development project. The goal is to identify local Bicknell’s Thrush concentrations/distribution, habitat used and potential impacts of the windmill project on its habitat and the species itself. At Mont Gosford, the 131 point-counts done in 2000-2004 were repeated to determine whether Bicknell’s Thrush abundance and occurrence has changed. Results are pending.

Marc Mazerolle is currently analysing data from Quebec and Maritimes to determine the detectability of BITH.

back to top

Caribbean

1994-97 BITH distribution and habitat use study in Dominican Republic

1997-2007 Intensive mid-winter demographic monitoring of BITH and other montane forest birds in Sierra de Bahoruco; includes training of local biologists

• Constant-effort mist-netting, point counts, spot mapping
• 429 individual BITH captured in D.R. (490 total captures) and 22 individuals in Haiti (25 total captures)
• 2 VT-DR recoveries (Rimmer and McFarland 2001, Townsend and Rimmer 2006)

1998-99 BITH surveys conducted in Blue and John Crow Mts of Jamaica.

• Low BITH numbers in Blue Mts, none found in John Crow Mts

1999 Yves Aubry initiated surveys in Cuba in 1999 with local collaborators Alejandro Llanes from the Instituto de Ecologia y Sistematica and Arturo Kirkconnell from the Museo Nacional de Historia Natural both in La Havana.

• Many areas were visited throughout the island of Cuba. Bicknell’s Thrush was located only in the high altitude cloud forests of the Sierra Maestra. So far, no bird has been found at low altitude.

2001-07 BITH sexual habitat selection and overwinter ecology research (Jason Townsend PhD work)

• Data show 4:1 male:female ratio in undisturbed primary montane forests of DR, 1:1 ratio in more disturbed secondary montane forests.
• Males and females occupy discrete territories in primary forest of ~0.35 ha based on radio telemetry.

2001-07 Collection of mercury samples on Hispaniola and Cuba

• Data show blood Hg up to 3X higher than in North America (Rimmer et al. 2005)
• Data collection expanded in 2007 to include OVEN and several endemics across Hispaniola.

2004-07 BITH surveys conducted in two protected areas of Haiti (Macaya and La Visite)

• BITH found in broadleaf forest fragments at mid- and high elevations

2005 Hispaniola eBird implemented

2006 Birds of the Dominican Republic and Haiti published (Latta et al. 2006)

back to top

United States (Monitoring, Research)

Monitoring

1992-94 VINS (now VCE) and Manomet Center for Conservation Sciences conduct a distributional survey for BITH in U.S. Northeast (Atwood et al. 1995, Rimmer et al. 1995)

2000 Mountain Birdwatch (MBW) piloted in Vermont, building on a small network of high-elevation forest bird monitoring routes already active in Vermont and Maine

2001 MBW expanded to include 160 sites in five states, 120 of which are monitored annually. Preliminary BITH distribution model completed for U.S.

2002 Conservation status of BITH habitat assessed throughout U.S. range

2003 MBW first projects effects of climate change on future distribution of BITH.  MBW and HELP align protocols.

2004 MBW measures 9% annual decline in BITH on 47 routes surveyed every year (2001-2004)

2005 A practical model of BITH distribution published in Wilson Bulletin 117:1-11.  Numbers of BITH and other target species appear to rebound.

2006 MBW collaborates with US Forest Service on White Mountain National Forest (WMNF) 1993-2003 trend analysis for BITH and other species; BITH show significant 7% annual decline

2007 Mountain Bird Working Group of the Northeast Coordinated Bird Monitoring Partnership is formed.

2007 WMNF trend analysis published (King et al. 2007)

2007 Projected effects of climate change (Rodenhouse et al. 2008)

2007 Mountain Birdwatch joins Avian Knowledge Network

back to top

Research

1993-2007 Intensive demographic and ecological BITH studies on Mt. Mansfield (1993-2007), Stratton Mountain (1997-2007), and East Mountain (2004-2007) in Vermont.  Highlights through 2007 include:

• 1,208 individual BITH captured (2,351 total captures)
• 182 nests monitored
• Sex ratio 2.2 males:1 female, consistent across range (including Quebec)
• Documentation of biennial cycle of cone crops-red squirrel populations-avian breeding success and recruitment; peer-reviewed paper to be submitted Dec 2007

1995-97 Fall stopover ecology study on Mt. Mansfield, published in (Rimmer and McFarland 2000)

• Results suggest few transient BITH, most adults remaining on or close to breeding territories through Sept; montane forests important BTBW post-fledging habitat

1997-2003 Studies of ski area impacts on BITH on Mt. Mansfield and Stratton Mountain, VT

• Primary findings that existing ski areas have few detectable effects on BITH reproductive success, nest predation rates, behavior, or adult survivorship; 2004 report “Evaluating the use of Vermont ski areas by Bicknell’s Thrush: applications for Whiteface Mountain, New York”

1998-2001 Research on BITH mating system and breeding ecology

• Documented polygynandry in BITH, with multiple paternity and multiple male feeders, male-biased sex ratio (Goetz et al. 2003)
• Fledging success positively correlated with prey biomass on female home range, # male feeders negatively correlated Strong et al. 2004).

2000 Collection of BITH blood and feather samples for mercury begins (also Canada); ongoing

• Mercury pervasive in BITH across range, feather Hg levels increase with age; (Rimmer et al. 2005)

2001 Walter Ellison PhD dissertation on population structure and gene flow in BITH and VEER

• mDNA analyses showed no significant population structure in BITH, indicating considerable gene flow

2001 BITH Birds of North America account published (Rimmer et al 2001)

2001 “Bicknell’s Thrush Conservation Assessment” report to U.S. Forest Service

2001 Tail feather stable isotopes from U.S. and Canadian sites suggest mixing of breeding populations on Hispaniola (Hobson et al. 2001)

2004-07 Baseline data collection for study of wind power impacts to BITH on East Mountain, VT; Turbine construction denied in 2006; future of research undetermined.

2005 “Bicknell’s Thrush Conservation Strategy for the Green Mountain National Forest” report to U.S. Forest Service

2005-07 Collection of data on mercury in the montane food web (leaf litter, foliage, arthropods, BITH), under contract to US Environmental Protection Agency

2007 Historic mercury levels examined via analysis of feathers from 75 museum specimens across breeding range

back to top