Canadian Journal of Zoology, Ahead of Print.
Examining multiple niche relationships, such as habitat use and activity patterns, between sympatric species contributes to an understanding of the mechanisms of coexistence and competition. Sika deer (Cervus nippon Temminck, 1838) and Japanese serows (Capricornis crispus (Temminck, 1836)) often show different habitat use, and diversity in vegetation and topography seems to facilitate their coexistence. Conversely, their habitat use may overlap in areas with low-diversity habitats; however, this remains unstudied. Moreover, whether they spatiotemporally avoid each other to reduce direct interference is unclear. We examined the fine-scale patterns of habitat use and activity of deer and serows in the subalpine forests of Mount Fuji, which have low-diversity habitats, using camera trapping data over 3 years. Deer and serow habitat niches largely overlapped, especially in summer (92%–94%) and autumn (89%–91%), suggesting that low-diversity habitats facilitate overlapping habitat use. Both species selected areas frequently used by the other during spring to autumn and their temporal niches largely overlapped, especially in summer (88%) and autumn (83%), suggesting that they do not spatiotemporally avoid each other (i.e., there is no direct interference). Rapid range expansion of deer into these subalpine habitats may exclude native serows through resource exploitative competition rather than interference competition.
Category Archives: NRC Research Press: Canadian Journal of Zoology
The relative importance of cisco (Coregonus artedi) in the diets of common loons (Gavia immer) among a set of cisco refuge lakes in Minnesota
Canadian Journal of Zoology, Ahead of Print.
Common loon (Gavia immer (Brünnich, 1764)) foraging patterns and the relative importance of cisco (Coregonus artedi Lesueur, 1818) in the diets of loons were evaluated for the Whitefish Chain of Lakes, a set of coldwater cisco refuge lakes in Minnesota, USA. Environmental DNA metabarcoding of loon fecal samples detected 15 fish species. Yellow perch (Perca flavescens (Mitchill, 1814)), mimic shiner (Notropis volucellus (Cope, 1865)), and cisco were the most prominent prey detected across the study lakes. We observed a shift in fish species consumed, with increases in detections of mimic shiner and cisco DNA among loon fecal samples collected in August and September. In some locations, suitable oxythermal habitat became restricted throughout the summer, forcing cisco into surface waters, which potentially increased their vulnerability to loon predation. Conversely, large foraging aggregations of loons were observed during late summer through fall at locations with ample oxythermal habitat and abundant cisco populations. We hypothesize that cisco were sought by loons as a high-calorie prey resource prior to migration. Conservation efforts directed at preserving water quality in important cisco refuge lakes are likely to benefit common loons through enhancement of both the forage base, for resident and migrating birds, and breeding habitat suitability.
Common loon (Gavia immer (Brünnich, 1764)) foraging patterns and the relative importance of cisco (Coregonus artedi Lesueur, 1818) in the diets of loons were evaluated for the Whitefish Chain of Lakes, a set of coldwater cisco refuge lakes in Minnesota, USA. Environmental DNA metabarcoding of loon fecal samples detected 15 fish species. Yellow perch (Perca flavescens (Mitchill, 1814)), mimic shiner (Notropis volucellus (Cope, 1865)), and cisco were the most prominent prey detected across the study lakes. We observed a shift in fish species consumed, with increases in detections of mimic shiner and cisco DNA among loon fecal samples collected in August and September. In some locations, suitable oxythermal habitat became restricted throughout the summer, forcing cisco into surface waters, which potentially increased their vulnerability to loon predation. Conversely, large foraging aggregations of loons were observed during late summer through fall at locations with ample oxythermal habitat and abundant cisco populations. We hypothesize that cisco were sought by loons as a high-calorie prey resource prior to migration. Conservation efforts directed at preserving water quality in important cisco refuge lakes are likely to benefit common loons through enhancement of both the forage base, for resident and migrating birds, and breeding habitat suitability.
Cytogenetic, molecular, and morphological characterization of Odocoileus pandora (Merriam, 1901) (Artiodactyla, Cervidae)
Canadian Journal of Zoology, Ahead of Print.
The Yucatan brown brocket deer was initially described as Mazama pandora Merriam, 1901. Phylogenetic analysis of mitochondrial DNA recovered the species as sister group of the genus Odocoileus and subsequently the species was repositioned to this genus naming Odocoileus pandora (Merriam, 1901). However, there is still a lack of taxonomic consensus that could assist in nomenclature definition of the species. We aim to clarify the taxonomy of O. pandora through an integrative assessment using morphological, cytogenetic, and molecular data from recently collected specimens. Morphological characterizations identified O. pandora as a medium-sized brocket deer. The skull shows an inflated auditory bulla and a narrow zygomatic arch. Males present long, broad, spike-like antlers converging inward, marked with deep longitudinal grooves. Odocoileus pandora shows a karyotype with 2n = 60 FN = 74. Bacterial artificial chromosome clone hybridization showed that centric and tandem fusions, and inversions are involved in karyotypical divergences between O. pandora, S. gouazoubira, M. americana, and O. virginianus. Our phylogeny based on Bayesian Inference of mitogenome recovered O. pandora as monophyletic within the subtribe Odocoileina, with Odocoileus as sister taxa. Morphological and genetic characteristics of O. pandora agrees in differencing the Yucatan brown brocket from Mazama and Odocoileus genera. Therefore, a new generic name should be indicated for this taxon.
The Yucatan brown brocket deer was initially described as Mazama pandora Merriam, 1901. Phylogenetic analysis of mitochondrial DNA recovered the species as sister group of the genus Odocoileus and subsequently the species was repositioned to this genus naming Odocoileus pandora (Merriam, 1901). However, there is still a lack of taxonomic consensus that could assist in nomenclature definition of the species. We aim to clarify the taxonomy of O. pandora through an integrative assessment using morphological, cytogenetic, and molecular data from recently collected specimens. Morphological characterizations identified O. pandora as a medium-sized brocket deer. The skull shows an inflated auditory bulla and a narrow zygomatic arch. Males present long, broad, spike-like antlers converging inward, marked with deep longitudinal grooves. Odocoileus pandora shows a karyotype with 2n = 60 FN = 74. Bacterial artificial chromosome clone hybridization showed that centric and tandem fusions, and inversions are involved in karyotypical divergences between O. pandora, S. gouazoubira, M. americana, and O. virginianus. Our phylogeny based on Bayesian Inference of mitogenome recovered O. pandora as monophyletic within the subtribe Odocoileina, with Odocoileus as sister taxa. Morphological and genetic characteristics of O. pandora agrees in differencing the Yucatan brown brocket from Mazama and Odocoileus genera. Therefore, a new generic name should be indicated for this taxon.
Short-term exposure to near-future CO2 has limited influence on the energetics and behaviour of young-of-year salmonids
Canadian Journal of Zoology, Ahead of Print.
In many freshwater ecosystems, carbon dioxide (CO2) is increasing. Unknown are the risks that high CO2 poses for freshwater organisms, especially fish. The objective of this study was to determine how CO2 may influence the growth rate, metabolic rate, feeding rate, and volitional behaviour of young-of-year Arctic charr (Salvelinus alpinus (Linnaeus, 1758)), brook charr (Salvelinus fontinalis (Mitchill, 1814)), and rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)). For this study, fish stayed in control (1100 microatmospheres (µatm)) or elevated (5236 µatm) CO2 levels for 15 days. During this time, metabolic rate and behavioural tests were conducted on alternating days for each treatment. Weight and length of each fish were taken on days 0, 7, and 15. There was no evidence that elevated CO2 affected the growth rate, feeding rate, or behaviour in any of these species. The standard metabolic rate in Arctic charr differed based on CO2 exposure. Therefore, salmonids can withstand short periods of elevated CO2 under these conditions. By comparing closely related species, the implications of this work are more ecologically relevant and will also help industry quantify the effects of high CO2 on young salmonids.
In many freshwater ecosystems, carbon dioxide (CO2) is increasing. Unknown are the risks that high CO2 poses for freshwater organisms, especially fish. The objective of this study was to determine how CO2 may influence the growth rate, metabolic rate, feeding rate, and volitional behaviour of young-of-year Arctic charr (Salvelinus alpinus (Linnaeus, 1758)), brook charr (Salvelinus fontinalis (Mitchill, 1814)), and rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)). For this study, fish stayed in control (1100 microatmospheres (µatm)) or elevated (5236 µatm) CO2 levels for 15 days. During this time, metabolic rate and behavioural tests were conducted on alternating days for each treatment. Weight and length of each fish were taken on days 0, 7, and 15. There was no evidence that elevated CO2 affected the growth rate, feeding rate, or behaviour in any of these species. The standard metabolic rate in Arctic charr differed based on CO2 exposure. Therefore, salmonids can withstand short periods of elevated CO2 under these conditions. By comparing closely related species, the implications of this work are more ecologically relevant and will also help industry quantify the effects of high CO2 on young salmonids.
The physiological state of four commercially important bivalve species during a naturally occurring heatwave
Canadian Journal of Zoology, Volume 101, Issue 10, Page 913-929, October 2023.
Shallow coastal environments are becoming more susceptible to marine heatwaves, particularly in Atlantic Canada, which is experiencing higher rates of ocean warming compared with the global average. Understanding bivalves’ tolerance to heatwaves in Atlantic Canada is especially important, given the magnitude of bivalve aquaculture in this region. In this study, the physiological state of four commercially important bivalve species—blue mussel (Mytilus edulis Linnaeus, 1758), eastern oyster (Crassostrea virginica (Gmelin, 1791)), soft shell clam (Mya arenaria Linnaeus, 1758), and hard clam (Mercenaria mercenaria (Linnaeus, 1758))—was observed during a naturally occurring heatwave in Prince Edward Island, Canada. The metabolism, feeding physiology, and scope for growth of each species were compared. Results from this study, and comparisons with the literature, show interspecific variability in the metabolic rate and feeding physiology between species, but generally oysters, soft shell clams, and hard clams were less impacted during the heatwave compared with the blue mussels. Additionally, only the scope for growth of mussels declined throughout this experiment, which may be explained by cumulative heat stress, as temperatures experienced during this heatwave exceeded the thermal tolerance limits of mussels.
Shallow coastal environments are becoming more susceptible to marine heatwaves, particularly in Atlantic Canada, which is experiencing higher rates of ocean warming compared with the global average. Understanding bivalves’ tolerance to heatwaves in Atlantic Canada is especially important, given the magnitude of bivalve aquaculture in this region. In this study, the physiological state of four commercially important bivalve species—blue mussel (Mytilus edulis Linnaeus, 1758), eastern oyster (Crassostrea virginica (Gmelin, 1791)), soft shell clam (Mya arenaria Linnaeus, 1758), and hard clam (Mercenaria mercenaria (Linnaeus, 1758))—was observed during a naturally occurring heatwave in Prince Edward Island, Canada. The metabolism, feeding physiology, and scope for growth of each species were compared. Results from this study, and comparisons with the literature, show interspecific variability in the metabolic rate and feeding physiology between species, but generally oysters, soft shell clams, and hard clams were less impacted during the heatwave compared with the blue mussels. Additionally, only the scope for growth of mussels declined throughout this experiment, which may be explained by cumulative heat stress, as temperatures experienced during this heatwave exceeded the thermal tolerance limits of mussels.
Short-term effects of camera trap installation on incubation constancy in cranes
Canadian Journal of Zoology, Volume 101, Issue 10, Page 896-903, October 2023.
Research regarding how birds respond to the installation of cameras at nest sites is limited. We installed cameras at nests of Sandhill Cranes Antigone canadensis (Linnaeus, 1758) and federally endangered Whooping Cranes Grus americana Linnaeus, 1758 in Juneau County, WI, as part of an ongoing study monitoring the reproductive success of Whooping Cranes in WI. The eastern population of Sandhill Cranes has grown, while Whooping Crane population growth has been slow, prompting the need to monitor the reproductive success of cranes on the refuge. We recorded the flight initiation distance during camera installation, the return time after camera installation, as well as measured the distance at which cameras were placed from each nest. We included temperature at camera deployment, age of nest, mode of access, ordinal date, and year in statistical regression models. We found an apparent difference in the observed flight initiation distances between the two species. Sandhill Cranes allowed researchers to approach their nests closer than Whooping Cranes prior to flushing. The post-disturbance return time was influenced by how far away the cameras were placed from the nest and the ambient temperature during camera deploy. Our study may help inform decisions regarding species response to methods and distance when deploying cameras, especially for endangered or disturbance-sensitive species.
Research regarding how birds respond to the installation of cameras at nest sites is limited. We installed cameras at nests of Sandhill Cranes Antigone canadensis (Linnaeus, 1758) and federally endangered Whooping Cranes Grus americana Linnaeus, 1758 in Juneau County, WI, as part of an ongoing study monitoring the reproductive success of Whooping Cranes in WI. The eastern population of Sandhill Cranes has grown, while Whooping Crane population growth has been slow, prompting the need to monitor the reproductive success of cranes on the refuge. We recorded the flight initiation distance during camera installation, the return time after camera installation, as well as measured the distance at which cameras were placed from each nest. We included temperature at camera deployment, age of nest, mode of access, ordinal date, and year in statistical regression models. We found an apparent difference in the observed flight initiation distances between the two species. Sandhill Cranes allowed researchers to approach their nests closer than Whooping Cranes prior to flushing. The post-disturbance return time was influenced by how far away the cameras were placed from the nest and the ambient temperature during camera deploy. Our study may help inform decisions regarding species response to methods and distance when deploying cameras, especially for endangered or disturbance-sensitive species.
Variation in the supercooling points of laboratory-reared Canadian Dermacentor variabilis (Acari: Ixodidae)
Canadian Journal of Zoology, Volume 101, Issue 10, Page 930-935, October 2023.
The geographical range of the American dog tick, Dermacentor variabilis (Say, 1821) in Canada is expanding northwards into areas where ticks experience colder temperatures during winter. Understanding the ability of D. variabilis to cope with freezing temperatures is important for determining what limits the distributional range of this species. In this study, the supercooling point (SCP = the sub-zero temperature at which freezing occurs) was measured for 318 laboratory-reared D. variabilis individuals (109 nymphs and 209 adults). These ticks were reared from questing adult ticks collected from an area adjacent to Blackstrap Provincial Park in Saskatchewan, Canada. The results showed that there was no relationship between the SCP and body weight of adult ticks, and no difference in the SCP of female and male ticks. However, the mean SCP of nymphs (−23.6 °C) was significantly lower than that of adults (−21.6 °C). The biological significance of this finding needs to be explored further given that D. variabilis larvae and adults are the primary overwintering stages at northern latitudes.
The geographical range of the American dog tick, Dermacentor variabilis (Say, 1821) in Canada is expanding northwards into areas where ticks experience colder temperatures during winter. Understanding the ability of D. variabilis to cope with freezing temperatures is important for determining what limits the distributional range of this species. In this study, the supercooling point (SCP = the sub-zero temperature at which freezing occurs) was measured for 318 laboratory-reared D. variabilis individuals (109 nymphs and 209 adults). These ticks were reared from questing adult ticks collected from an area adjacent to Blackstrap Provincial Park in Saskatchewan, Canada. The results showed that there was no relationship between the SCP and body weight of adult ticks, and no difference in the SCP of female and male ticks. However, the mean SCP of nymphs (−23.6 °C) was significantly lower than that of adults (−21.6 °C). The biological significance of this finding needs to be explored further given that D. variabilis larvae and adults are the primary overwintering stages at northern latitudes.
Structure of breeding calls in three closely related bird species (Calidris Merrem, 1804; Scolopacidae)
Canadian Journal of Zoology, Volume 101, Issue 10, Page 869-885, October 2023.
We studied calls of three sandpiper species to document species’ similarities and differences. We hypothesized that functionally different calls would differ in degree of divergence. We studied two nuptial calls (complex “Song” and rhythmically repeated aerial call, RRC) of males, and a general-purpose call (“alarm” trill, AT) given by parents of both sexes in the presence of humans and other potential predators, in great knot, Calidris tenuirostris (Horsfeld, 1821); surfbird, Calidris virgata (Gmelin, 1789); and red knot, Calidris canutus (Linnaeus, 1758). Calls diverged unevenly across species—RRCs and Song diverged the most and ATs the least. Vocalizations of great knot and surfbird were most similar to one another, in agreement with a recently proposed phylogeny. Despite species differences in single acoustic traits, calls were evolutionarily conservative at higher structural levels, such as rhythmic temporal delivery of RRCs and harmonic structure (e.g., the fundamental frequency was suppressed in some call types). Some acoustic qualities that differed across species were similar across call types within species (e.g., tonality in red knot calls). Trait similarity across different calls suggests that a species’ calls cannot evolve independently of one another: common mechanisms of vocal production across different calls may impede differentiation within a species’ repertoire.
We studied calls of three sandpiper species to document species’ similarities and differences. We hypothesized that functionally different calls would differ in degree of divergence. We studied two nuptial calls (complex “Song” and rhythmically repeated aerial call, RRC) of males, and a general-purpose call (“alarm” trill, AT) given by parents of both sexes in the presence of humans and other potential predators, in great knot, Calidris tenuirostris (Horsfeld, 1821); surfbird, Calidris virgata (Gmelin, 1789); and red knot, Calidris canutus (Linnaeus, 1758). Calls diverged unevenly across species—RRCs and Song diverged the most and ATs the least. Vocalizations of great knot and surfbird were most similar to one another, in agreement with a recently proposed phylogeny. Despite species differences in single acoustic traits, calls were evolutionarily conservative at higher structural levels, such as rhythmic temporal delivery of RRCs and harmonic structure (e.g., the fundamental frequency was suppressed in some call types). Some acoustic qualities that differed across species were similar across call types within species (e.g., tonality in red knot calls). Trait similarity across different calls suggests that a species’ calls cannot evolve independently of one another: common mechanisms of vocal production across different calls may impede differentiation within a species’ repertoire.
Effects of bat white-nose syndrome on hibernation and swarming aggregations of bats in Ontario
Canadian Journal of Zoology, Volume 101, Issue 10, Page 886-895, October 2023.
Emerging infectious diseases can have substantial impacts on wildlife health, but also provide an opportunity to understand how populations respond to novel selective pressures. White-nose syndrome (WNS) has decimated some populations of bats in eastern North America, but impacts vary among species. We counted bats in 11 hibernacula in Ontario, Canada, before and after WNS arrived, and compared the relative abundance of 5 bat species captured pre-WNS (1966–1968 and 2007–2009) and post-WNS (2017–2019) during swarming at one of these hibernacula. Counts of hibernating bats declined by 87%–100% after WNS arrived. However, we observed a recent, gradual increase in bat counts in the two largest, monitored hibernacula. During swarming, little brown bat (Myotis lucifugus (Le Conte, 1831)) was the most frequently captured bat in all sampling periods. Capture frequency of northern long-eared bat (Myotis septentrionalis (Trouessart, 1897)) declined precipitously after WNS arrived, while eastern small-footed bat (Myotis leibii (Audubon and Bachman, 1842) represented a higher proportion of bat captures in 2017–2019 compared to other sampling periods. Our data suggest potential adaptation of some bat populations to WNS, but also highlight the importance of protecting bats and their habitat during the active season to facilitate population recovery.
Emerging infectious diseases can have substantial impacts on wildlife health, but also provide an opportunity to understand how populations respond to novel selective pressures. White-nose syndrome (WNS) has decimated some populations of bats in eastern North America, but impacts vary among species. We counted bats in 11 hibernacula in Ontario, Canada, before and after WNS arrived, and compared the relative abundance of 5 bat species captured pre-WNS (1966–1968 and 2007–2009) and post-WNS (2017–2019) during swarming at one of these hibernacula. Counts of hibernating bats declined by 87%–100% after WNS arrived. However, we observed a recent, gradual increase in bat counts in the two largest, monitored hibernacula. During swarming, little brown bat (Myotis lucifugus (Le Conte, 1831)) was the most frequently captured bat in all sampling periods. Capture frequency of northern long-eared bat (Myotis septentrionalis (Trouessart, 1897)) declined precipitously after WNS arrived, while eastern small-footed bat (Myotis leibii (Audubon and Bachman, 1842) represented a higher proportion of bat captures in 2017–2019 compared to other sampling periods. Our data suggest potential adaptation of some bat populations to WNS, but also highlight the importance of protecting bats and their habitat during the active season to facilitate population recovery.
Effects of brood viability and rising temperature on oxygen consumption of freshwater mussel glochidia (Bivalvia: Unionidae)
Canadian Journal of Zoology, Volume 101, Issue 10, Page 859-868, October 2023.
Unionid mussels are imperiled worldwide. Understanding the impacts of thermal and hypoxia stress on larval (glochidia) and adult physiology is critical for understanding the potential impacts of climate change. We tested whether brood viability (proportion of glochidia competent to attach to a host) was correlated with oxygen demand (MO2), ability to regulate oxygen consumption (regulation index (RI)), and/or critical dissolved oxygen concentration (DOcrit). We then examined the effects of temperature on MO2, RI, and DOcrit. The results were coupled with a previous study to estimate the fraction of brooding female oxygen demand comprised of glochidial respiration. We found little evidence that respiratory patterns of glochidia changed with declining brood viability, but strong evidence for decreasing glochidial RI and increasing DOcrit with increasing temperatures. Glochidial respiration temperature coefficient (Q10) values were approximately 2–3× those estimated for brooding females, indicating greater temperature sensitivity. The proportion of gravid female respiration comprised of glochidial respiration reached its maximum at temperatures (23–28 °C) coinciding with brood expulsion. These patterns suggest high temperatures may have deleterious effects on unionids by decreasing the hypoxia tolerance of glochidia, increasing the rate at which glochidia deplete energy reserves, and increasing the proportion of oxygen consumption by gravid females that is comprised of glochidial oxygen demand.
Unionid mussels are imperiled worldwide. Understanding the impacts of thermal and hypoxia stress on larval (glochidia) and adult physiology is critical for understanding the potential impacts of climate change. We tested whether brood viability (proportion of glochidia competent to attach to a host) was correlated with oxygen demand (MO2), ability to regulate oxygen consumption (regulation index (RI)), and/or critical dissolved oxygen concentration (DOcrit). We then examined the effects of temperature on MO2, RI, and DOcrit. The results were coupled with a previous study to estimate the fraction of brooding female oxygen demand comprised of glochidial respiration. We found little evidence that respiratory patterns of glochidia changed with declining brood viability, but strong evidence for decreasing glochidial RI and increasing DOcrit with increasing temperatures. Glochidial respiration temperature coefficient (Q10) values were approximately 2–3× those estimated for brooding females, indicating greater temperature sensitivity. The proportion of gravid female respiration comprised of glochidial respiration reached its maximum at temperatures (23–28 °C) coinciding with brood expulsion. These patterns suggest high temperatures may have deleterious effects on unionids by decreasing the hypoxia tolerance of glochidia, increasing the rate at which glochidia deplete energy reserves, and increasing the proportion of oxygen consumption by gravid females that is comprised of glochidial oxygen demand.