Douglas C. Tozer

Common Loon Reproductive Success in Canada: the West is Best but Not for Long

Reproductive success of Common Loons (Gavia immer) is a powerful indicator of aquatic ecosystem health, especially in relation to mercury and acid precipitation. We examined relationships between Common Loon reproductive success and longitude, year, lake area, and pH across southern Canada using data collected from 1992 to 2010 by participants in Bird Studies Canada’s Canadian Lakes Loon Survey. Our goal was to indirectly describe the health of lakes in southern Canada with respect to mercury and acid precipitation. The overall model-predicted number of six-week-old young per pair per year was 0.59 (95% confidence limits: 0.56–0.62). Six-week-old young per pair per year decreased by 0.19 from west-to-east (−127° to −52° longitude), decreased by 0.14 between 1992 and 2010, increased by 0.22 as lake area increased from 10 to 3000 ha, and increased by 0.43 as acidity decreased from pH 5 to 9. The relationships were likely linked to acidand temperature-mediated exposure to methylmercury and/or acid-induced reductions in forage fish. The temporal decrease was unexpectedly steeper in southwestern than in southeastern Canada. Projections suggested that reproductive success across southern Canada may not drop below the demographic source-sink threshold until ~2016 (range: 2009-2029). Reproductive success on pH 6.0 lakes, however, may have passed below the source-sink threshold as early as ~2001 (1995-2009), whereas reproductive success on pH 8.0 lakes may not pass below the threshold until ~2034 (2019-2062). There were ~0.1 more six-week-old young per pair per year on 2500 ha lakes than on 20 ha lakes. Reproductive success crossed below the source-sink threshold on 20 ha lakes at pH 6.4 (5.8–7.1) and on 2500 ha lakes at pH 5.5 (4.1–6.6). Our results show that citizen science is powerful for monitoring ecosystem health and indirectly support further action to abate emissions of mercury and the harmful components of acid precipitation throughout North America and globally. RESUME. Le succes reproducteur du Plongeon huard (Gavia immer) est un indicateur puissant de la sante des ecosystemes aquatiques, particulierement sur le plan du mercure et des precipitations acides. Nous avons examine les relations entre le succes reproducteur du plongeon et la longitude, l’annee, la superficie du lac et son pH, dans l’ensemble du sud du Canada a l’aide des donnees recoltees de 1992 a 2010 par les participants de l’Inventaire canadien des Plongeons huards chapeaute par Etudes d’oiseaux Canada. Cette etude visait la description indirecte de la sante des lacs du sud du Canada, plus particulierement en ce qui a trait au mercure et aux precipitations acides. Le nombre global de jeunes de six semaines par couple et par an predit par le modele s’elevait a 0,59 (limites de confiance a 95 % : 0,56-0,62). Le nombre de jeunes de six semaines par couple et par an a diminue de 0,19 de l’ouest vers l’est (du 127e au 52e degre de longitude ouest), a diminue de 0,14 de 1992 a 2010, a augmente de 0,22 avec l’augmentation de la superficie du lac de 10 a 3000 ha, et enfin, a augmente de 0,43 avec la baisse de l’acidite, d’un pH de 5 a 9. Les relations etaient vraisemblablement liees a l’exposition au methylmercure induite par la temperature et l’acidite, et/ou a la reduction des poissons-fourrage induite par l’acidite. La baisse observee sur le plan temporel etait plus prononcee dans le sud-ouest que dans le sud-est du Canada – un resultat imprevu. Les projections indiquent que le succes reproducteur dans l’ensemble du sud du Canada pourrait ne pas descendre sous le seuil demographique source-puits avant ~2016 (etendue : 2009-2029). Toutefois, le succes reproducteur sur les lacs de pH 6,0 pourrait etre passe sous le seuil source-puits des ~2001 (1995-2009), tandis que le succes sur les lacs de pH 8,0 pourrait ne pas descendre sous ce seuil avant ~2034 (2019-2062). Il y avait ~0,1 jeune de six semaines par couple et par an de plus sur les lacs de 2500 ha comparativement aux lacs de 20 ha. Le succes reproducteur etait inferieur au seuil source-puits sur les lacs de 20 ha et de pH 6,4 (5,8-7,1) et sur les lacs de 2500 ha et

Prevalence of Disjunct Roosting in Nesting Bank Swallows (Riparia riparia)

ABSTRACT Bank Swallows (Riparia riparia) congregate in large nocturnal roosts during the non-breeding season. Scant evidence suggests that Bank Swallows may also congregate regularly in nocturnal roosts during the breeding period. To help clarify the issue, we used automated radio-telemetry to document the roosting behavior of 11 males and 11 females that were tending nests with young at two nesting colonies. Nineteen of the 22 birds (86%) spent at least one night roosting away from the colony, and 13 of the 22 birds (59%) spent at least one night roosting likely within a large marsh located ~30 km away from the colonies. Females tended to roost overnight at the colony more than males. The proportion of nights birds spent roosting away from the colony was highly variable between individuals. Minimum flight speeds to an evening roost site (~30 km distant) were significantly greater than return flights back to the colony in the morning. Our study confirms that breeding Bank Swallows do in fact regularly roo...

Observations of American Marten (Martes americana) Feeding at Sap Wells of Yellow-Bellied Sapsuckers (Sphyrapicus varius)

Abstract Martes americana (American Marten) is reported to eat a diverse diet, including mammals, invertebrates, and plants. Despite this variety, we found no reference to tree sap in its diet. Here, we describe two separate incidents of an American Marten feeding on sap from active sap wells made by Sphyrapicus varius L. (Yellow-bellied Sapsucker). To our knowledge, these are the first recorded observations of martens feeding on sap from sap wells.

Tree cavity use by Chimney Swifts: implications for forestry and population recovery

The Chimney Swift (Chaetura pelagica) is an aerial insectivore and a cavity-nesting/roosting specialist designated as threatened in several jurisdictions. As the occurrence of suitable chimneys declines, Chimney Swifts may increasingly nest and roost in tree cavities. It is therefore important to identify characteristics of suitable nest or roost trees and assess their frequency of occurrence. We reviewed 59 historic and modern records of trees used by Chimney Swifts to understand characteristics of suitable nest or roost trees. Chimney Swifts used at least 13 different deciduous and coniferous tree species. All of the trees were greater than 0.5 m diameter at breast height (DBH) and were described as hollow or having cavities. Nest or roost tree height was 12.7 ± 7.0 m (mean ± SD; range: 3.6– 28.0 m; n = 25) and DBH was 1.0 m ± 0.5 m (range 0.5–2.1 m; n = 21). According to our description of used trees, the number of suitably hollow Chimney Swift nest or roost trees may be two to three times higher, although still rare, in most unlogged compared to logged hardwood forests. Whether the current total supply of suitable nest or roost trees is sufficient to carry the anticipated increase in use by Chimney Swifts as chimney habitat is modified or deteriorates is unknown. Monitoring the frequency of use of tree cavities by nesting and roosting Chimney Swifts over time, and more robustly quantifying the availability of suitable tree cavities in different forest types for nesting and roosting Chimney Swifts, particularly in unlogged versus logged forests, are fruitful areas for future research. Utilisation de cavites d’arbres par le Martinet ramoneur : incidence sur les plans de l’exploitation forestiere et du retablissement des populations RESUME. Designe « menace » par plusieurs autorites concernees, le Martinet ramoneur (Chaetura pelagica) est un insectivore aerien et un specialiste de cavites dans lesquelles il niche et dort. Etant donne que le nombre de cheminees propices a leur nidification est en diminution, les martinets nichent et dorment peut-etre davantage dans les cavites d’arbres. Il apparait alors important d’identifier les caracteristiques des arbres favorables a la nidification ou au repos et d’evaluer leur frequence d’occurrence. Afin de cerner ces caracteristiques, nous avons passe en revue les mentions historiques et contemporaines d’arbres utilises par cette espece. Les Martinets ramoneurs ont utilise au moins 13 essences de feuillus ou de coniferes. Tous les arbres avaient un diametre a hauteur de poitrine (DHP) superieur a 0,5 m et etaient creux ou portaient des cavites. Leur hauteur etait de 12,7 ± 7,0 m (moyenne ± ecart type) (etendue : 3,6-28,0 m; n = 25) et leur DHP s’elevait a 1,0 ± 0,5 m (etendue : 0,5-2,1 m; n = 21). D’apres la description des arbres occupes, le nombre d’arbres creux convenables pour la nidification ou le repos du Martinet ramoneur pourrait etre de 2 a 3 fois plus eleve – quoique ces arbres sont quand meme rares – dans la plupart des forets de feuillus non-recoltees, comparativement aux forets recoltees. Nous ne savons pas si la quantite actuelle d’arbres propices est suffisante pour satisfaire l’utilisation accrue anticipee par les Martinets ramoneurs vu la deterioration ou la destruction des cheminees. Le suivi temporel de la frequence d’utilisation des cavites d’arbres par les martinets pour y nicher ou y dormir et une meilleure quantification de la disponibilite de cavites d’arbres propices dans differents types de forets, en particulier les forets intactes versus recoltees, sont des avenues de recherche prometteuses.

URBAN: Development of a Citizen Science Biomonitoring Program Based in Hamilton, Ontario, Canada.

Due to increasing urbanization, wetlands and streams within city limits are being altered, filled in, and degraded. The habitat that remains is critical for providing urban areas with ecosystem services and maintaining biodiversity, yet is often insufficiently monitored by environmental agencies due to a lack of resources. To help fill this void, the Urban-Rural Biomonitoring and Assessment Network (URBAN) was developed as a citizen science education and outreach program for Hamilton, Ontario, Canada. Through this program, volunteers gain insight into the dynamics of biological systems, learn how to identify species, and may experience growth personally in terms of environmental stewardship or even career path decisions. The implementation and development of URBAN followed a nine-step model developed by the Cornell Lab of Ornithology. Here, we offer an overview of URBANs development, successes, and challenges by utilizing this citizen science model as a guideline.