Rodger D. Titman

Habitat selection by forest bats in relation to mixed-wood stand types and structure in Central Ontario

Recent studies have suggested that old-growth forests may be important habitat for some species of bats, but the proximate factors related to greater bat activity in older forests are not well understood. To assess relative habitat use by bats, we used ultrasonic detectors and mist nets to sample bat activities among old-growth white pine (Pinus strobus) mixed woods, mature white pine mixed woods, boreal-type mixed woods, and selectively logged white pine mixed woods in central Ontario. We Quantified 15 structural characteristics in the 21 stands sampled for bat activity. Detection rates of Myotis species, silver-haired bats (Lasionycteris nocitvagans), and hoary bats (Lasiurus cinereus) were 2.7-14.0 times greater in old-growth white pine mixed-wood stands than in other stand types (Ps < 0.05). Multivariate habitat models suggested that, between logged and uncut stands, the availability of potential roost sites may be an important determinant of bat activity for Myotis species and silver-haired bats. Among uncut stands, our habitat models suggested that snag availability was not an important variable affecting habitat selection by bats. Rather, bat detection rates in uncut forests were correlated with canopy and subcanopy structure. Little brown bats (Myotis lucifugus) and northern long-eared bats (M. septentrionalis) may spatially separate for feeding To maintain habitat for bats, forest managers should implement timber harvest strategies that retain remnant old-growth white pine stands in the landscape, preserve snags and large live trees in selectively logged forests, and promote regeneration of second-growth white pine stands to old age rather than truncating age classes at younger ages.

Nektonic invertebrate abundance and distribution at the emergent vegetation-open water interface in the Delta Marsh, Manitoba, Canada

The emergent vegetation-open water interface plays an important role in the use of freshwater wetlands by many species of animals. The objective of this study was to monitor the distribution and abundance of free-swimming invertebrates at the cattail (Typha × glauca Godr.)—open water interface in two bays (sheltered and unsheltered) in the Delta Marsh in south-central Manitoba during 1985. Submersed vegetation densities were higher in the open water sites of the sheltered bay during most of the summer. Water temperatures were constant across the interface through much of the year. By mid-summer, hypoxic conditions prevailed within the water column in the cattail stand. Algae levels were similar across the interface throughout much of the year, with peaks occurring just inside the interface in June and July. Early in the season, there was a trend for higher nektonic invertebrate numbers within the cattail stands of both bays. By late August, there were similar total invertebrate numbers across the interface. Cladocera and ostracod numbers were higher within the cattail stands during June and July; during the same periods, corixid levels were higher in the open water sites. The low oxygen levels within the cattail stands during the summar may reduce predation by fish and other predators that cannot tolerate low oxygen levels. This may explain the higher numbers of prey species like cladocerans and ostracods within the cattail stands during mid-summer. The presence of algal or detrital food resources seemed to have little influence on invertebrate abundance across the interface during this study. Peaks in invertebrate abundance did not occur at the emergent vegetation-open water interface during any of the sampling periods in this study. The high invertebrate diversity and abundance in interspersed wetland habitat may be related more to the mixture of habitat types rather than the amount of interface present.

Nutrient additions to wetlands in the Interlake region of Manitoba, Canada: effects of a single pulse addition in spring

This study examined the responses of algae and invertebrates to a single application of N and P in a series of experimental wetland enclosures in the Interlake region of Manitoba during 1989 and 1990. N and P levels in the water, sediment and vegetation were also monitored. The 3 fertilization treatments were: dissolved inorganic (6200 μg 1-1 N, 420 μg 1-1 P), dissolved inorganic (3200 μg 1-1 N, 210 μg 1-1 P) and organic (ground alfalfa meal: 6200 μg 1-1 N, 420 μg 1-1 P).

Nutrient additions to wetlands in the Interlake region of Manitoba, Canada: effects of periodic additions throughout the growing season

The Interlake region of central Manitoba is characterized by numerous shallow, relatively unproductive wetlands. Typically, these wetlands are poorly utilized by breeding waterfowl in spite of generally reliable water conditions during spring and summer. Nutrient additions were made throughout the growing season to 18 PVC enclosures installed in a low productivity wetland near Lundar, Manitoba. Inorganic phosphorus (as H3PO4) and nitrogen (as NH4NO3) were added at bi-weekly intervals during the summer of 1988 at target rates of 0 and 0, 30 and 800, and 60 and 1600 μg 1-1 (P and N respectively). Algal and invertebrate communities were monitored from mid-June to September, 1988. Phytoplankton, epiphytic periphyton and metaphyton communities demonstrated significant increases in biomass over the treatment period. No significant differences in epipelon community biomass were noted. An examination of several indicators of nutrient deficiency indicated that algal productivity was moderately to severely limited in all enclosures, with little or no mitigative effects noted due to nutrient addition treatment. No significant differences in numbers or biomass of total invertebrates or invertebrate functional groups attributed to fertilization were observed. Nutrient additions did increase community productivity, however the levels used in this study were insufficient to yield a sustained increase in primary or secondary productivity.

Historical Changes in White Pine (Pinus strobus L.) Density in Algonquin Park, Ontario, During the 19th Century

Abstract Understanding historical forest condition is important as a basis for forest restoration and the development of forest management policies. White pine (Pinus strobus L.) historically has been an important commercial tree species, and significant post-settlement declines in its populations have been suggested in eastern North America since the 1600s. Logging of white pine in eastern Ontario, Canada, began in the late 1700s. We estimated the loss of white pine and changes in white pine diameter distribution in Algonquin Provincial Park by direct sampling of old stumps, censussing trees in an area that has never been harvested, assessing Crown Surveyors records from the 1800s, using a GIS mapping technique to assess probabilistic change in pine-dominated stands, and comparing our data to other published information. Stump and tree densities since the 1800s suggested a mean reduction in the number of white pine trees of 88% from about 3 to >8 pines/ha to <1 pine/ha today in mixed and deciduous stands. GIS-based mapping predicted a maximum decline of pine-dominated stands of about 40% by area, from 539 km2 that may have historically supported such forests. The diameter distribution of the current white pine trees was significantly smaller than in the historical forest (means, 44.5 cm vs. 73.4 cm, P < 0.001). Aside from early over logging, the continued low density of white pine in all forest types can be attributed in part to intense post-logging fires in the 1800s and to the past 60 years of fire suppression, which have eliminated seed sources and seedbeds. We suggest that a program using several silvicultural techniques will be necessary to restore the white pine in forest types that existed historically.

Nutrient status of wetlands in the Interlake Region of Manitoba, Canada

Preliminary observations indicated that the productivity of wetlands in the Interlake region of Manitoba, Canada is low, resulting in limited use by waterfowl and other wildlife species. This study compared nutrient availability, algal biomass, and invertebrate abundance and biomass between two Interlake wetlands. The Narcisse site was a typical Interlake wetland with no known source of external nutrient input. The Cruise Marsh site was a wetland similar to the Narcisse site except for the operation of a cattle feedlot on its shore. Total dissolved and suspended N and P levels were higher at the Cruise Marsh site throughout much of the year. Phytoplankton and epiphytic periphyton biomass were also much higher at Cruise Marsh. The water chemistry and biomass of these two algae groups found in the Narcisse site were similar to levels characteristic of oligotrophic lakes. The algae at Narcisse also showed severe N and P deficiency throughout the year, while no similar deficiency was observed at Cruise Marsh. Epipelon biomass in unvegetated Narcisse sites was higher than found in vegetated Narcisse sites or at Cruise Marsh. Invertebrate abundance and biomass were lower at Narcisse. Cruise Marsh invertebrate abundance and biomass approached levels found in the more eutrophic Delta Marsh. The Narcisse wetlands do appear to be nutrient limited, which in turn affects the algae and higher order consumers like invertebrates. These low invertebrate levels likely play a role in the low use by waterfowl and other marsh birds in these wetlands.

BREEDING BIOLOGY AND NESTING SUCCESS OF LOGGERHEAD SHRIKES IN ONTARIO

Abstract The migrant race of the Loggerhead Shrike (Lanius ludovicianus migrans) has undergone a severe decline in Canada since the mid-1950s and was designated as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 1991. In order to gain a better understanding of the factors that may be associated with the decline of this species in eastern Canada, we studied the breeding biology and nesting success of Loggerhead Shrikes in the three core breeding areas in Ontario, Canada, during 1991 and 1992. We located 27 breeding pairs during 1991 and 50 breeding pairs during 1992. Mean clutch size was 4.9 and 5.6, mean number of eggs hatched per nest was 4.2 and 5.4, and mean number of young fledged per nest was 3.9 and 4.2 in 1991 and 1992, respectively. Only 2.3 and 2.5 young per pair survived to independence in each year. Percent success in fledgling at least one young was 89% and 78%. We believe that predation was the cause of all but one of the nest failures in both years. One pair successfully double brooded in 1991. In 1992 one of three double-brooding attempts was successful. The probability of survival of an egg was 58.6% for nests in isolated red cedars (Juniperus virginiana), 76.2% in isolated hawthorn (Crataegus spp.) shrubs, 88.5% in hawthorn shrubs in hedgerows, and 92.9% for all other species of nest tree. Daily nest survival was 98% for nests in isolated red cedar trees and 100% for nests in isolated hawthorn shrubs, in hawthorn shrubs in hedgerows, and in all other species of nest tree. Nest depth ranged from 11.2–12.4 cm and nest height above ground ranged from 2.1–2.5 m. Most nests in red cedar and other species of trees were located adjacent to the main trunk. Nests in hawthorn shrubs were located adjacent to the main trunk, on a main branch, or in the center of the canopy.

Shrub-nesting birds in urban habitats: their abundance and association with vegetation

Shrub-nesting bird species are infrequent inhabitants of urban habitats. Our study identifies their location within urban bird assemblages, quantifies their abundance in an urban ecosystem, and explores their association with vegetation variables. The study design consists of 103 point locations distributed among four types of urban habitat: medium-density residential sectors, low-density residential sectors, urban parks and natural parks. We focused on six shrub-nesting species: Gray Catbird (Dumetella carolinensis), Yellow Warbler (Setophaga petechia), Chipping Sparrow (Spizella passerine), Song Sparrow (Melospiza melodia), Northern Cardinal (Cardinalis cardinalis), and Red-winged Blackbird (Agelaius phoeniceus). Results from the PERMANOVA analysis suggest that the types of urban habitat are significantly different based on bird composition. Shrub-nesting species observed in Montreal were most abundant in natural parks, but some were frequently observed in residential areas. The presence of some shrub-nesting species was, depending on the type of urban habitat, associated with higher abundance of deciduous shrubs, clumps of shrubs or deciduous trees. This was not the case with all shrub-nesting species nor in all types of urban habitat.

Spatial-genetic structuring in a red-breasted merganser (Mergus serrator) colony in the Canadian Maritimes.

The clustering of kin is widespread across the animal kingdom and two of the primary mechanisms underlying the formation of these patterns in adult kin are (1) philopatric tendencies and (2) actively maintained kin associations. Using polymorphic microsatellites, we had set out to characterize the level of genetic-spatial organization within a colony of female red-breasted mergansers (Mergus serrator) breeding on a series of small barrier islands in Kouchibouguac National Park, NB, Canada. Additionally, using nesting data from this colony, we explored possibilities for the existence of kin associations and/or cooperative interactions between these individuals; specifically in the form of the synchronization of breeding activities (i.e., incubation initiation). Our results include: (1) the detection of broad-scale genetic structuring over the entire colony, as females nesting on separate islands were to some extent genetically distinct; (2) the detection of weak, yet significant, positive spatial autocorrelation of kin at the fine scale, but only in the more densely-populated areas of this colony; and (3) the synchrony of breeding activities among proximally nesting females, apart from any factors of relatedness. While these results confirm the existence of genetic-spatial organization within this colony, the underlying mechanisms producing such a signal are inconclusive.

Movements and habitat use by Red-breasted Merganser broods in eastern New Brunswick

Abstract Red-breasted Mergansers (Mergus serrator) commonly breed in estuaries, but little is known about their brood-rearing in coastal environments. We measured daily movements and habitat use of radio-marked (n = 17) female Red-breasted Mergansers with broods originating from coastal barrier islands at Kouchibouguac National Park, New Brunswick, Canada from 2002 to 2004. Primary brood movements from nest sites to initial rearing areas were often extensive, averaging 3.5 km (n = 15), since many broods crossed Saint-Louis Lagoon to continental rearing sites. Broods remained mobile throughout the rearing period and there was little difference in daily movements between age class I (days 1–10 post nest exodus), class II (days 11–20), and class III (>20 days) broods. Broods frequented shallow (x̄ = 51 cm, 95% CI: 44–58 cm, n = 191 locations), nearshore (x̄ = 47 m, 95% CI: 33–60 m, n = 157 locations) waters that often supported submergent eel grass (Zostera marina). Broods selected estuarine intertidal regions in Saint-Louis and Kouchibouguac lagoons, as well as wetlands at the mouths of tidal streams. Few broods were found in tidal river and marine habitats. Continental estuarine intertidal, tidal stream, and saltmarsh habitats were preferred by age class I broods whereas estuarine intertidal and subtidal habitats were preferred by age classes II and III. This study highlights the importance of estuarine habitats in lagoons and tidal streams for brood-rearing Red-breasted Mergansers in eastern New Brunswick.