88, Badzinski 2007, Hitch and Leberg 2007, Melles Et Al

Nest site characteristics of Hooded Warblers at the northern edge of their breeding range By Benjamin J. Walters and Erica Nol

Introduction The northern limit of the breeding range of the Hooded Warbler ( Setophaga citri - na ) extends from southeastern Nebraska to the southern Great Lakes Region and includes Wisconsin, Michigan, southern Ontario and New York (Chiver et al. 2011). The southern limit of the Hooded Warbler’s breeding range extends from Florida to eastern Texas, although breeding in California has been documented (Chiver et al. 2011). Hooded Warblers have been undergoing a population and range expansion in the northeastern portion of their range (Gartshore 1988, Badzinski 2007, Hitch and Leberg 2007, Melles et al . 2011). For example, between the first (1981 – 1985) and second (2001 – 2005) Ontario Breeding Bird Atlas, Hooded Warblers were found in 68 new 10 km x 10 km atlas squares, and 12 of the same squares, while the species became absent in eight squares (Cadman et al . 2007). The expansion has generally been attributed to climate change (Hitch and Leberg 2007, Melles et al. 2011), but may Photo by also be a result of increases in suitable Ben Walters forested habitat within portions of its range (Badzinski 2007).

88 Ontario Birds August 2011 Ganaraska Forest

Figure 1. Location of the Ganaraska Forest owned by the Ganaraska Region Conservation Authority.

The Hooded Warbler is listed as a Friesen et al. 2000, Whittam et al. “threatened” species in the federal 2002, Badzinski 2003). Species at Risk Act , and a “special con - Some breeding evidence north of cern” species in Ontario’s Endangered this range, such as a male feeding young Species Act , 2007. Less than 1% of the east of Peterborough, Ontario, in 1963 Hooded Warbler’s breeding range is in (Sadler 1968), has been reported, but a Canada (Environment Canada 2011) breeding population was not discov - and all of that is in southern Ontario ered. Evidence now suggests that (Badzinski 2007). The first document - Hooded Warblers may breed as far ed occurrence of the Hooded Warbler north as the Bruce Peninsula, Lake at the northern extent of its range in Simcoe-Rideau and the southern Can - Ontario was in 1878 and nesting was adian Shield regions (Badzinski 2007). first documented in 1949 (Peck and For example, an unsuccessful breeding James 1987). The northern extent of attempt was documented at Awenda the Canadian Hooded Warbler popula - Provincial Park in 1989 (Weir 1989) tion was considered to inhabit primari - and a pair with fledged young w as ly Carolinian Forests in southwestern observed there in 2010 (Friends of Ontario (Bisson and Stutchbury 2000, Awenda Park 2011).

Volume 29 Number 2 89 Hooded Warblers mainly breed in harvest (Gart shore 1988, Heltzel and mid- to late-successional mixed decidu - Leberg 2006) and in hurri cane created ous forests. At the northern extent of gaps after two and three years (Green - their range, such as in Ontario, Penn - berg and Lanham 2001) rather than in sylvania, Ohio, and Missouri, they control stands without gaps. In some breed in beech-maple and oak-hickory regions, Hooded Warblers are observed dominated forests (Horn and Ben - only in sites that have undergone forest ninger-Truax 1997, Friesen et al . 2000, harvesting (Wallendorf et al. 2007, this Howlett and Stutchbury 2003, Wallen - study ). As well, because of their prefer - dorf et al . 2007, Chiver et al . 2011). At ence for dense understory, nesting can the southern edge of their range they occur close to skidder trails, old logging breed in wet lowlands such as cypress- roads and roads (Gartshore 1988, gum swamps (Heltzel and Leberg Howlett and Stutchbury 1996). 2006). Hooded Warblers will also In 2006, a small nesting population inhabit forests with coniferous compo - of Hooded Warbler was observed in the nents such as oak-pine in south-central Ganaraska Forest in south-central Ont - Missouri (Wallendorf et al. 2007), ario, approximately 200 km north of mature pine forests in North (Green - the previously documented northern berg and Lanham 2001) and South range (Friesen et al. 2000) (Fig. 1). Un - Carolina (Sargent et al. 1997) and coni - like the southwestern Ont ario popula - ferous plantations in southwestern tion in the Carolinian Forest Zone, this (Badzinski 2003) and south-central south-central Ontario population Ont ario ( this study ). inhabits the Great Lakes-St. Lawrence Hooded Warblers prefer mature Forest Zone. Similarly, however, the forests with a high canopy (Whittam Ganaraska Forest is mainly underlain and McCracken 1999), dense under - by sandy soils as is much of this species’ story, and canopy gaps for nest sites distribution in Ontario’s Carolinian and territories (Gartshore 1988, Whit - Forest (Gartshore 1988). The Ganaras - tam and McCracken 1999, Bisson and ka Forest is composed of beech-maple Stutchbury 2000, Friesen et al . 2000, and oak-maple forest with some mixed Pasher et al. 2007). Hooded Warbler pine-oak forest and coniferous planta - nest sites would naturally be found in tions. Som e trees and shrub s such as tree-fall gaps (Chiver et al. 2011), but tulip-tree ( Liriodendron tulipifera ), sas - because of a lack of mature forest safras ( Sassafras albidum ) and spicebush throughout their range, they are typi - (Lindera benzoin ), that are present in cally found in sites that are selectively the Hooded Warbler’s south western logged (Tarof and Stutchbury 1996, Ont ario breeding habitat, are absent Whittam and McCracken 1999, from the Gan araska Forest. Therefore, Greenberg and Lanham 2001). Hood - differences in forest structure such as ed Warblers appear to be more abun - tree spacing, canopy height and clo - dant at sites within 12 to 18 years after sure, and shrub laye r density, between

90 Ontario Birds August 2011 Figure 2. Deciduous habitat used by nesting Hooded Warblers in the Ganaraska Forest. Photo by Ben Walters the Carolinian Forest Zone and the they could be the same across this Ganaraska Forest could result in differ - species’ Canadian range. Furthermore, ences in habitat selection. Our objective identifying the similarities or differ - was to determine whether the structure ences in structural characteristics would of nesting habitat in the Ganaraska For - help in future assessments of potential est was similar to that in other areas of breeding habitat availability in the this species’ range, particularly in Great Lakes-St. Lawrence Forest Z one. southwestern Ontario. Determining We expected that Hooded W ar blers the similarity in nest-site habitat would use nest -site s with th e sam e requirements among forest types would structural charac teristics as as individu - be useful for understanding what forest als to the south , despite a difference in management practices are most benefi - forest type. We expected that, because cial to Hooded Warblers and whether Hooded Warblers are a gap-dependent

Volume 29 Number 2 91 species (Bisson and Stutchbury 2000, surroun ding land use is largely agricul - Shifley et al. 2006), nesting habitat tural. Pa sture lands for horse and cattle would be structurally similar to areas production dominate with some hay to the south with dense undergrowth fields and few row crops. Similar to the and an open canopy. St. Williams forest where a large per - centage of Canada’s Hooded Warblers Methods breed (Whittam et al. 2002), tree har - Study area vesting in the Ganaraska Forest is per - The Ganaraska Forest (N44° 5.8’ formed by either single-tree selection W78° 30.5’), owned by the Ganaraska in mixed deciduous forest or row-thin - Region Conservation Authority, is a ning in pine plantations. 4,228 ha forest on the Oak Ridges Moraine (Figure 1). The boundaries of Nest site vegetation the Ganaraska Forest are within characteristics Durham Regional Municipality, an d Hooded Warbler nest sites were located Peterboroug h and Northumberland in 2006 ( n = 4) and 2007 ( n = 8) counties. Forest soils are dominated by through intensive foot searches near Pontypool series gravely sand, Dun - singing males and agitated females. donald sandy loam, Bridgman sand Vegetation characteristics were meas - and Pontypool sandy loam underlain ured at eight of the 12 sites in 200 7. by Black River Trenton group lime - We measured the habitat character - stone. Forest elevations range from 200 istics at nest sites within a 5m x 10m m to 408 m above sea level (Tedford area centered on the nest. The habitat 1978). variables measured included percent In the early 1900s, reforestation of cover of overstory canopy cover, stem the Ganarask a Forest was necessar y density of saplings and trees, ground to stabilize the soils that began to erode cover and vegetation stratification after they were cleared for farmland. (Kilgo et al. 1996). We then compared The forest is approximately equally the vegetation characteristics from the comprised of coniferous plantation nest patch to the vegetation character - and mixed hardwoods. The coniferous istics at randomly chosen unused sites plantations consist of red pine ( Pinus (Kilgo et al. 1996, Bisson and Stutch - resin osa ) with smaller areas of scots bury 2000). To test nest-site selection, pine ( Pinus sylvestris ), jack pine ( Pinus we pooled nests from 2006 and 2007 bank siana ), white spruce ( Picea glau - because of small sample sizes (Whittam ca ), European larch ( Larix deciduas ) et al. 2002). and American larch ( Larix laricina ). All statistical analyses were per - The mixed hardwoods are dominated formed using STATISTICA (Statsoft by red oak ( Quercus rubra ), sugar 2004). Normality was tested using the maple ( Acer sacc harum ) and poplar Kolmorogov-Smirnov test and homo - (Populus spp .) (Tedford 1978). The geneity of variances was tested using

92 Ontario Birds August 2011 the Levene’s test. Variables tha t were distance. Litter depth was measured at normally distributed, or normalized the edge of the plot in all cardinal direc - using a transformation, were tested for tions and at the centre point of the plot. their difference between nest sites and Measurements at each site were pooled non-use sites using independent t-tests. to create a mean depth for each site. Data that were not normally distributed Coarse woody debris (CWD) was were transformed using log(k) or counted along a 10 m transect which log(k+1) to meet the assumptions of was defined as 1 m on either side of the parametric testing. If data could not be eastern boundary of the vegetation plot normalized, the difference between nest (20 m 2). CWD was classified as small sites and non-use sites was tested using a CWD (<2.5 cm circumference), medi - Mann-Whitney U test. um CWD (2.6 – 8 cm circumference), To assess percent cover within the and large CWD (>8 cm circumference). nest and random unused sites, vegeta - Lastly, all classes at each site were pooled tion was vertically stratified as follows: to create a total abundance of CWD for Ground cover = <0.5 m; Regeneration = each site. For testing of the pooled >0.5 m and <1.3 m; Saplings = >1.3 m CWD, one site was removed from the <2.5 m; Understory = >2.5 m and <10 non-use sites as it had no CWD and m; Sub-canopy = >10 m and < 20 m; was a severe outlier affecting normality. Canopy = >20 m. Percent cover esti - Basal area, the area of land that is mates were categorized as follows: 0% = covered by the cross-sections of woody 1; 1 – 25% = 2; 26 – 50% = 3; 51 – stems (m 2/ha), was measured using a 75% = 4; 76 – 100% = 5 Kilgo et al. 2X prism centred on the nest or at the 1996, Moorman et al. 2002. Because of centre of the plots in the non-use sites. the high degree of correlation within From the non-use sites, two sites that the percent cover classes, one variable were measured in large openings such as was removed from each correlated pair on roads at logging landings were not (Moorman et al. 2002). Within the per - used as they severely affected normality. cent cover classes, the uncorrelated vari - Once these outliers were removed, para - ables analyzed were regeneration and metric tests could be used without understory. All trees (>25 cm circumfer - transformation. ence), saplings (>1.3 m high and <7.8 Canopy cover was measured using a cm circumference) and shrubs within spherical densiometer. Four measure - the plot were counted and classed as ments were taken by standing at the either dead or alive. The vegetation plot centre point and extending the den - rectangle was quartered into quadrats siometer in each cardinal direction. The by assigning boundaries along each car - measure ments from each direction were dinal direction. The distance to the multiplied by 1.04 as required by the nearest tree and the nearest sapling in instructions for the instrument to each of the quadrats was measured. Dis - approximate 100% coverage, and the tances were then pooled into a mean results were averaged.

Volume 29 Number 2 93 have increased between 2006 and Table 1. Comparisons of the percent cover in the regeneration layer between Hooded Warbler nest 2007. By colour-banding males sites and randomly chosen non-use sites in the with individually identifiable pat - Ganaraska Forest, Ontario, 2006 – 2007. terns in 2007, we were able to determine that two nests with Class Nest sites Non-use sites nestlings were being attended by (n = 4) (n = 62) the same male. 1 (0%) 0 (0%) 3 (5%) All but one Hooded Warbler nest found in the Ganaraska For - 2 (1 – 25%) 0 (0%) 44 (71%) est were placed in gaps created by 3 (26 – 50%) 3 (75%) 12 (19%) silvicultural wood removal. Hood - ed Warblers chose four different 4 (51 – 75%) 1 (25%) 3 (5%) nest substrates: elderberry ( Sam - 5 (76 – 100%) 0 (0%) 0 (0%) bucus sp. ), 3 (25%); sugar maple (Acer saccharum ), 6 (50%); rasp - berry ( Rubus sp .), 2 (17%), and Table 2. Comparisons of the percent cover in the beaked hazel ( Corylus cornuta ), 1 understory layer between Hooded Warbler nest (8% ). The average nest height was sites and randomly-chosen non-use sites in the 0.56 m ± 0.10 (mean ± standard Ganaraska Forest, Ontario, 2006 – 2007. error). Most nests were placed in Class Nest sites Non-use sites the crot ch of nest substrates or on (n = 4) (n = 62) a platform created by branches. One nest how ever, was placed 1 (0%) 0 (0%) 7 (11%) where a dead branch touched the 2 (1 – 25%) 1 (25%) 29 (47%) stem of a sapling and the edges o f the nes tontw o sides wer e 3 (26 – 50%) 2 (50%) 16 (15%) attache dtothe substrate at the 4 (51 – 75%) 1 (25%) 9 (15%) top of the nest cup. The nest was very flimsy and had begun to dis - 5 (76 – 100%) 0 (0%) 1 (2%) integrate by the time of fledging. This nest was also different because it was found in a medi - um-aged patch of forest approxi - Results mately 10 m from the ne arest typical We observed four nests (probably of gap nesting habitat. three nesting pairs) and five males (two Because we had percent cover esti - unpaired) in 2006, and eight nests in mates for a few sites only ( n = 4), we did 2007 (probably of seven nesting pairs) not analyze them statistically. Hooded and 14 males (seven unpaired). Search Warbler nest sites were found in areas effort was similar in the two years so the with a high percent cover (between 26 – local breeding population appears to 75 % cover) i n th e regeneration layer

94 Ontario Birds August 2011 Table 3. Comparison of vegetation characteristics between Hooded Warbler nest sites and randomly chosen non-use sites in the Ganaraska Forest, Ontario, 2006 – 2007.

Parameter Nest Site h Non-use Site h Pi

Live tree density (# of trees/50 m 2)b 2.6 ± 0.7 3.1 ± 0.3 0.74

Dead tree density (# of trees/50 m 2)a,b 0 (range 0 – 3) 0 (range 0 – 5) 0.66

Live sapling density (# of saplings/50 m 2)b 27.9 ± 7.8 9.3 ± 1.0 <0.0001

Dead sapling density (# of saplings/50 m 2)b 0.8 ± 0.5 1.3 ± 0.3 0.005

Shrub density (# of shrubs/50 m 2)a,d 43 (range 7 – 66) 3 (range 0 – 125) 0.02

Mean distance to trees (cm) c 510.0 ± 42.2 438.1 ± 39.1 0.25

Mean distance to saplings (cm) c 184.3 ± 48.7 414.4 ± 41.9 0.007

Distance to nearest tree (cm) c 249.9 ± 22.0 272.6 ± 38.3 0.45

Distance to nearest sapling (cm) c 64.4 ± 14.9 191.8 ± 30.9 0.058

Litter depth (cm) e 3.6 ± 1.2 3.3 ± 0.2 0.7

CWD small (# of pieces/20 m 2)d 43.5 ± 9.8 42.1 ± 4.0 0.93

CWD medium (# of pieces/20 m 2)d 9.3 ± 1.7 5.2 ± 0.6 0.06

CWD large (# of pieces/20 m 2)d 1.5 ± 0.5 2.3 ± 0.5 0.86

CWD total (# of pieces/20 m 2)d 54.3 ± 10.0 49.6 ± 4.4 0.51

Basal Area (m 2/ha) f 18.8 ± 1.3 23.5 ± 1.1 0.12

Canopy cover (#/100 units) g 27.6 ± 3.8 31.8 ± 4.7 0.98

a Mann-Whitney U test e Nest site ( n = 3); Non-use site ( n = 61) b Nest site ( n = 8); Non-use site ( n = 62) f Nest site ( n = 8); Non-use site ( n = 60) c Nest site ( n = 7); Non-use site (n = 62) g Nest site ( n = 4); Non-use site ( n = 22) d Nest site ( n = 4); Non-use site i Mean ± standard error (n = 62) CWD: Coarse woody debris h Significant results ( P<0.05) are bolded.

(between 0.5 m and 1.3 m from the Similarly, although not analysed ground) of the Ganaraska Forest (Table statistically, nest sites were found at 1). Although the sample size was small, locations with proportionally more this observation was disproportionate cover in the understory layer (between to the non-use sites which had a higher 2.5 m and 10 m from the ground) than distribution in the lower regeneration non-use sites (Table 2). While non-use class of 1 – 25% cover. sites were found to occur within each

Volume 29 Number 2 95 Figure 3. Hooded Warbler nest containing four eggs in a sugar maple sapling, the most often used nesting substrate in the Ganaraska Forest. Photo by Ben Walters

perc ent cover class, they were distrib - There were significantly more living uted around class 2 (1 – 25%). Nest and fewer dead saplings at nest sites sites were distributed around class 3 (2 6 that at non-use sites (Table 3). As well, – 50%), suggesting that Hooded War - there were significantly more shrubs at blers in the Ganaraska Forest choose a nest sites than at non-use sites (Table denser understory. The variables that 3). In addition, the mean distance to were significantly different between saplings, measured from the nearest nest sites and non-use sites were: (1) sapling to the northwest, northeast, live sapling abundance; (2) dead southwest, and southeast was signifi - sapling abundance; (3) shrub density, cantly lower at nest sites than non-use and (4) mean distance to saplings. sites.

96 Ontario Birds August 2011 Figure 4. Female Hooded Warbler incubating eggs that included the first observed case of Brown-headed Cowbird parasitism in the Ganaraska Forest. Photo by Ben Walters

Discussion Gartshore 1988, Whittam and Hooded Warbler nest sites in the McCrac ken 1999, Bisson and Stutch - Ganar aska Forest were mostly in decid - bury 2000, Pasher et al. 2007). P ropor - uous dominated forest (Figure 2), tionally more often, Hood ed Warblers although two of the 12 nests were in in the Ganaraska Forest used sugar managed conifer plantations that were maple as the nesting substrate com - regenerating to mixed forest. The pref - pared to other substrates (Figure 3), erence of Hooded Warblers nests to be although the sample size of nests was in forest gaps with dense vegetation in small. Higher proportional use of sugar the lower regeneration layer in the maple as nest substrate had not been Ganaraska Forest was similar to the reported in other studies, however two preferences reported elsewhere ( e.g., of our nests were in raspberry brambles,

Volume 29 Number 2 97 Due to the success of the populations to the south, Hooded Warbler individuals appear to have emigrated north to suitable habitat

the preferred substrate of nests in south - cover further outside the nest western Ontario (Badzinski 2003). Nest patch than other studies. heights in the Ganaraska Forest (mean = The increased coverage out - 0.56 m) were similar to the heights side the nest patch would observed in the southwestern Ontario have decreased the overall (e.g. , mean = 0.48 m: Badzinski 2003), coverage by the opening. Penns ylvania (mean = 0.54 m: Howlett Because there were no appar - and Stutchbury 1996, mean = 0.51 m: ent differences among the Howlett and Stutchbury 1997) and nest sites at our study site in slightly lower than in South Carolina the Great Lakes-St. Law - (mean = 0.98 m: Kilgo et al. 1996; mean rence Forest Zone and the = 0.9 m <100 m from edge, and mean = nest sites to the south such as 0.8 m >100 m from edge: Moor man et al . in the Carolinian Forest 2002). Zone, we suggest that this Although Hooded Warblers in the new nesting population of Ganaraska chose nest sites in openings Hooded Warblers is part of a created by forest harvesting, we did not range expansion rather than observe a significant difference between attraction to a novel habitat the canopy cover at nest sites and non- feature. use sites. On average, canopy cover at Due to the success of the populations nest sites was lower, but the difference to the south, Hooded Warbler individu - was not statistically significant. Nest als appear to have emigrated north to sites in South Carolina also did not have suitable habitat, possibly as a result of a significantly different canopy cover at warming climate (Melles et al. 2011). nest sites (Kilgo et al. 1996); however, Forest harvesting practices in the other studies have found significantly Ganaraska Forest are similar to those in reduced canopy cover at nest sites southwestern Ontario ( e.g. , South Wals - (Whittam et al . 2002, Pasher et al . ingham and St. Williams Forest) and 2007). A potential reason for our results their populations have continued to differing from other studies is that we grow in those forests when suitable habi - used a spherical densiometer to measure tat is created by logging practices (Whit - canopy cover. Due to its concave mirror, tam and McCracken 1999). We expect we may have sampled forest canopy that unless a stochastic even t occurs to

98 Ontario Birds August 2011 Figure 5. An after second year male Hooded Warbler banded as part of research in the Ganaraska Forest. Photo by Ben Walters adversely affect nest productivity or the re-observed (BJW, pers. obs.). A major interannual survival of individuals of problem for more southern populations this new pop ulation, continued popula - is a high incidence of nest parasitism by tion growth and expansion will occur in Brown-headed Cowbirds ( Molothrus this Great Lakes-St. Lawrence Forest ater ). Zone population. However, until a nest containing a Interestingly, following the intensive Brown-headed Cowbird egg was found surveys for Hooded Warblers in 2007, in 2010 in the Ganaraska Forest (Figure the population has appeared to remain 4), no previous incidences of parasitism (as of July 2011) at approximately five had been detected. Therefore it is pairs and nesting as far north as Peter - unlikely that nest parasitism is a cause borough County in 2008 has not been of slow population growth. In fact, we

Volume 29 Number 2 99 could speculate that the novelty of Hooded Warbler nest sites in the Hooded Warbler nesting allowed them Ganaraska Forest to determine if the to go undetected until the local Brown- habitat structure was similar to the more headed Cowbirds became accustomed southern breeding population. We to Hooded Warbler nesting behavior. found that Hooded Warblers were The stability, rather than growth of this choosing to nest in forest gaps. The nest population may be an effect of the small sites in the gaps had higher vegetation number of annual recruits being offset density in the regeneration (>0.5 m and by interannual mortality and territorial <2.3 m) and understory (>2.5 m and abandonment by unpaired adults. In <10 m) layers than random locations. 2009, two years after banding many For example, most nest sites had fledglings and adults (Figure 5), we only 26–50% cover in the regeneration layer re-encountered a single banded male while most random locations had despite nesting occurring at similar ter - 1–25% cover. Similarly the greatest ritories. The difficulty of finding mates number of nest sites had 26–50% cover in a small population was exemplified in in the understory layer while most ran - 2008 when a male was observed mating dom locations had 1–25% cover. Nest with a female offspring from the previ - sites had significantly higher sapling and ous year. While geographic expansion of shrub densities than random locations. the Hooded Warbler populations pro - As we expected, Hooded Warblers vides a promising outlook for a stable appear to be choosing structural charac - Ontario population, population growth teristics in the Ganar aska Forest that are at the north ern limit appears slow. similar to those in more southern forest types. We detected only one case of Summary Brown-headed Cowbird parasitism in The population and range of the Hood - Hooded Warbler nests since 2006. ed Warbler has been expanding in Ontario. Once considered a species of Acknowledgments the Carolinian Forest Zone, Hooded We are grateful to the Ganaraska Warblers have continued to expand Region Conservation Authority for northward. In 2006, we found a previ - their support of the project and access ously unreported, small breeding popu - to the Ganaraska Forest. Funding for lation of Hooded Warblers in the this project was provided by the Ganaraska Forest, south of Peterbor - Ontario Ministry of Natural Resources ough, Ontario. This population repre - Species At Risk Stewardship Fund and sented a shift from being restricted to the Oak Ridges Moraine Foundation. the Carolinian Forest Zone in Canada We also thank Myles Falconer, Paul to inhabiting the Great Lakes-St. Law - Woodard, Andrea Geboers, Sara Pie per, rence Forest Zone. In 2007, we sought Alison Elliott and Erin Wiancko for to assess the habitat characteristics of field assistance.

100 Ontario Birds August 2011 Literature Cited Friends of Awenda Park . 2011. Bird Badzinski, D.S. 2003. Hooded Warbler Research (2010). A Friends of Awenda Park research in St. Williams Forest, Ontario; Online Publication. http://www. awenda - An investigation of nest productivity, nest park.ca/?page_id=550 concealment, territory size and species Friesen, L., M. Cadman, P. Carson, associations. Bird Studies Canada, K. Elliott, M. Gartshore, D. Martin, Port Rowan, Ontario. J. McCracken, J. Oliver, P. Prevett, Badzinski, D.S. 2007. Hooded Warbler, B. Stutchbury, D. Sutherland and pp. 524 – 525 in Cadman, M.D., D.A. A. Woodliffe. 2000. National recovery plan Sutherland, G.G. Beck, D. Lepage and for the Acadian Flycatcher ( Empidonax A.R. Couturier, eds. Atlas of the Breeding virescens ) and Hooded Warblers ( Wilsonia Birds of Ontario, 2001-2005. Bird Studies citrina ): national recovery plan no. 20; Canada, Environment Canada, Ontario recovery of nationally endangered wildlife Field Ornithologists, Ontario Ministry of (RENEW). Ottawa, Ontario. 33pp. Natural Resources and Ontario Nature, Gartshore, M.E. 1988. A summary of the Toronto, xxii + 706 pp. breeding status of Hooded Warblers in Bisson, I.A . and B.J. Stutchbury . 2000. Ontario. Ontario Birds 6: 85 – 99. Nesting success and nest-site selection by Greenberg, C.H. and J.D. Lanham . 2001. a neotropical migrant in a fragmented land - Breeding bird assemblages of hurricane-cre - scape. Canadian Journal of Zoology 78: ated gaps and adjacent closed canopy forest 858 – 863. in the southern Appalachians. Forest Ecolo - Cadman M.D., D.A. Sutherland, G.G. gy and Management 154: 251 – 260. Beck, D. Lepage and A.R. Couturier , eds. Heltzel, J.M . and P.L. Leberg . 2006. 2007. Atlas of the Breeding Birds of Effects of selective logging on breeding bird Ontario, 2001 – 2005. Bird Studies Cana - communities in bottomland hardwood da, Environment Canada, Ontario Field forests in Louisiana. Journal of Wildlife Ornithologists, Ontario Ministry of Natu - Management 70: 1416 – 1424. ral Resources and Ontario Nature, Toronto, Hitch, A.T. and P.L. Leberg . 2007. Breed - xxii + 706 pp. ing distributions of North American bird Chiver, I., L.J. Ogden and B.J. Stutch - species moving north as a result of climate bury . 2011. Hooded Warbler ( Wilsonia change. Conservation Biology 21: 534 – citrina ). In : The Birds of North America 539. Online. A. Poole, editor. Cornell Lab of Horn, D.J. and M. Benninger-Truax . Ornithology, Ithaca, New York. http://bna. 1997. The summer bird community in birds.cornell. edu.cat1.lib.trentu.ca:8080/ a late-successional beech-maple forest in bna/species/ 110doi:10.2173/bna.110 Ohio. Ohio Journal of Science 97: 14 – 16. Environment Canada . 2011. Recovery Howlett, J.S. and B.J.M. Stutchbury . strategy for the Acadian Flycatcher ( Empi - 1996. Nest concealment and predation in donax virescens ) and the Hooded Warbler Hooded Warblers: experimental removal of (Wilsonia citrina ) in Canada [Proposed]. nest cover. Auk 113: 1 – 9. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa, Ontario. ix + 32 pp.

Volume 29 Number 1 101 Howlett, J.S. and B.J.M. Stutchbury . Moorman, C.E., D.C. Guynn Jr. and J.C. 1997. Within-season dispersal, nest-site Kilgo . 2002. Hooded Warbler nesting suc - modification, and predation in renesting cess adjacent to group-selection and Hooded Warblers. Wilson Bulletin 109: clearcut edges in a southeastern bottom - 643 – 649. land forest. Condor 104: 366 – 377. Howlett, J.S. and B.J.M. Stutchbury . Pasher, J., D. King and K. Lindsay . 2007. 2003. Determinants of between-season Modelling and mapping potential Hooded site, territory, and mate fidelity in Hooded Warbler ( Wilsonia citrina ) habitat using Warblers ( Wilsonia citrina ). Auk 120: 457 remotely sensed imagery. Remote Sensing – 465. of the Environment 107: 471 – 483. Kilgo, J.C., R.A. Sargent, B.R. Chapman Peck, G.K. and R.D. James. 1987. Breed - and K.V. Miller . 1996. Nest-site selection ing birds of Ontario, nidology and distri - by Hooded Warblers in bottomland hard - bution, volume 2: passerines. The Royal woods of South Carolina. Wilson Bulletin Ontario Museum, Toronto, Ontario. 108: 53 – 60. Sadler, D.C. 1968. Birds of the Peterbor - Melles, S.J., M.-J. Fortin, K. Lindsay ough area and their seasonal movements. and D. Badzinski . 2011. Expanding Publisher unknown. Peterborough, northward: influence of climate change, Ontario. forest connectivity, and population Sargent, R.A., J.C. Kilgo, B.R. Chapman processes on a threatened species range. and K.V. Miller . 1997. Nesting success

Global Change Biology 17:17 – 31. of Kentucky and Hooded Warblers in bottomland forests of South Carolina. Wilson Bulletin 109: 233 – 238. Shifley, S.R., F.R. Thompson III, W.D. Dijak, M.A. Larson and J.J. Millspaugh . 2006. Simulated effects of forest management alternatives on landscape structure and habitat suitability in the Midwestern United States. Forest Birding • Nature • Optics • Books Ecology and Management 229: 361 – 377. &DQDGD·V/DUJHVW6HOHFWLRQRI%LQRFXODUVDQG6FRSHV $OODW'LVFRXQW3ULFHV Statsoft . 2004. Statistica 7. Tulsa, ‡6ZDURYVNL Oklahoma. ‡.RZD Tarof, S.A. and B.J.M. Stutchbury . ‡3HQWD[ 1996. A case of cooperative breeding in ‡/HLFD the Hooded Warbler. Wilson Bulletin ‡1LNRQ 108: 382 – 384. ‡6ZLIW ‡%XVKQHOO Tedford, J.A. 1978. Ganaraska Forest ‡=HLVV Study. Published by the Ganaraska Region ‡Steiner Conservation Authority and the Ontario ‡&HOHVWURQ ‡Manfrotto Ministry of Natural Resources, Port Hope, ‡9RUWH[ ‡BushHawk Ontario. )RU)$67 0DLO2UGHU'HOLYHU\RU4XRWH VDOHV#SHOHHZLQJVFD ZZZSHOHHZLQJVFD

102 Ontario Birds August 2011 Wallendorf, M.J., P.A. Porneluzi, Whittam, R.M., J.D. McCracken, W.K. Gram, R.L. Clawson and C.M. Francis and M.E. Gartshore . 2002. J. Faaborg . 2007. Bird response to The effects of selective logging on nest-site clear cutting in Missouri Ozark forests. selection and productivity of Hooded Journal of Wildlife Management 71: 1899 Warblers ( Wilsonia citrina) in Canada. – 1905. Canadian Journal of Zoology 80: 644 – Weir, R.D. 1989. Ontario Region. 654. American Birds 43: 1310 – 1313. Whittam, R.M. and J.D. McCracken . Benjamin J. Walters, Environmental and 1999. Productivity and habitat selection Life Sciences Graduate Program, Trent of Hooded Warblers in southern Ontario; University. Peterborough, Ontario K9J An interim report to the Endangered 7B8. E-mail: [email protected] Species Recovery Fund of the World Erica Nol , Biology Department, Trent Wildlife Fund Canada. Bird Studies University. Peterborough, Ontario Canada, Port Rowan, Ontario. K9J 7B8.

Volume 29 Number 2 103