Maria Florencia Miretti, Rodrigo Pol, Lucia Vullo, Ana Laura Cao, Luis Marone, Javier Lopez de Casenave
The study of diet and its relationship with available resources allows us to evaluate how species that differ in their degree of ecological flexibility respond to natural and anthropogenic variations that affect food availability. In the central Monte desert, extensive cattle ranching reduces the abundance of grass seeds, the most consumed and preferred food by the harvester ants Pogonomyrmex inermis Forel, 1914, P. mendozanus (Cuezzo & Claver, 2009), and P. propinqua (Johnson, 2021). We studied the diet of these species in grazed and ungrazed habitats over four years, including a period during which the abundance of grass seeds naturally decreased. We expected that ants would modify their diet in grazed sites and that the response would be different among species depending on their ecological flexibility. The three species presented a mainly granivorous diet in both grazing conditions and during the four years, but showed differences in the breadth of their diet. Pogonomyrmex inermis and P. propinqua always had a narrow diet that consisted mainly of grass seeds, while P. mendozanus modified its diet to include higher proportions of shrub seeds and other items when the abundance of grass seed decreased. In a scenario of scarce resources, this flexibility could represent an advantage over a more strict graminivorous diet.
{"title":"Diet flexibility in three harvester ants (Pogonomyrmex spp.): effects of grazing and natural variations in the availability of seeds","authors":"Maria Florencia Miretti, Rodrigo Pol, Lucia Vullo, Ana Laura Cao, Luis Marone, Javier Lopez de Casenave","doi":"10.1139/cjz-2023-0145","DOIUrl":"https://doi.org/10.1139/cjz-2023-0145","url":null,"abstract":"The study of diet and its relationship with available resources allows us to evaluate how species that differ in their degree of ecological flexibility respond to natural and anthropogenic variations that affect food availability. In the central Monte desert, extensive cattle ranching reduces the abundance of grass seeds, the most consumed and preferred food by the harvester ants Pogonomyrmex inermis Forel, 1914, P. mendozanus (Cuezzo & Claver, 2009), and P. propinqua (Johnson, 2021). We studied the diet of these species in grazed and ungrazed habitats over four years, including a period during which the abundance of grass seeds naturally decreased. We expected that ants would modify their diet in grazed sites and that the response would be different among species depending on their ecological flexibility. The three species presented a mainly granivorous diet in both grazing conditions and during the four years, but showed differences in the breadth of their diet. Pogonomyrmex inermis and P. propinqua always had a narrow diet that consisted mainly of grass seeds, while P. mendozanus modified its diet to include higher proportions of shrub seeds and other items when the abundance of grass seed decreased. In a scenario of scarce resources, this flexibility could represent an advantage over a more strict graminivorous diet.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"83 24","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135092076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Katherine Nicole McElroy, Ray Hilborn, Curry Cunningham, Thomas P. Quinn
Many foraging models assume “perfect information” and “free movement” when describing predator foraging behavior, although this is rare in nature. Here we quantified predation by brown bears (Ursus arctos, (Linnaeus, 1758)) on adult sockeye salmon (Oncorhynchus nerka, (Walbaum, 1792)) in a series of spatially proximate ponds that largely satisfied both assumptions. Salmon abundance varied among years but pond area and depth were fixed, allowing us to examine interactions between prey abundance and habitat features. We applied versions of two models to 25 years of data on the number and proportion of salmon killed by bears, modifying these models to include habitat features and temporal variability. The functional response model with a year effect fit the data well, indicating bears could take almost all salmon in ponds when salmon were scarce, but bears were sated when salmon were abundant. The proportion of salmon killed by bears was similar across habitats after correcting for pond depth and area. Overall, bears foraged across all habitats, but killed higher proportions of salmon in smaller and shallower habitats, consistent with ease of capture.
{"title":"Brown bear (Ursus arctos) foraging in a mosaic of spatially discrete and variable habitats over 25 years of shifting Pacific salmon densities","authors":"Katherine Nicole McElroy, Ray Hilborn, Curry Cunningham, Thomas P. Quinn","doi":"10.1139/cjz-2022-0178","DOIUrl":"https://doi.org/10.1139/cjz-2022-0178","url":null,"abstract":"Many foraging models assume “perfect information” and “free movement” when describing predator foraging behavior, although this is rare in nature. Here we quantified predation by brown bears (Ursus arctos, (Linnaeus, 1758)) on adult sockeye salmon (Oncorhynchus nerka, (Walbaum, 1792)) in a series of spatially proximate ponds that largely satisfied both assumptions. Salmon abundance varied among years but pond area and depth were fixed, allowing us to examine interactions between prey abundance and habitat features. We applied versions of two models to 25 years of data on the number and proportion of salmon killed by bears, modifying these models to include habitat features and temporal variability. The functional response model with a year effect fit the data well, indicating bears could take almost all salmon in ponds when salmon were scarce, but bears were sated when salmon were abundant. The proportion of salmon killed by bears was similar across habitats after correcting for pond depth and area. Overall, bears foraged across all habitats, but killed higher proportions of salmon in smaller and shallower habitats, consistent with ease of capture.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"4 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135589326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cristian Pérez-Granados, Mariano J. Feldman, Marc J. Mazerolle
Passive acoustic monitoring usually generates large datasets that require machine learning algorithms to scan sound files, although the complexity of developing machine learning algorithms can be a barrier. We assessed the ability and speed of two user-friendly machine learning tools, Kaleidoscope Pro and BirdNET, for detecting the American toad (Anaxyrus americanus, (Holbrook, 1836)) in sound recordings. We developed a two-step approach combining both tools to maximize species detection while minimizing the time needed for output verification. When considered separately, Kaleidoscope Pro successfully detected the American toad in 85.9% of recordings in the validation dataset, while BirdNET detected the species in 58.4% of recordings. Combining the two tools in the two-step approach increased the detection rate to 93.3%. We applied the two-step approach to a large acoustic dataset (n = 6,194 recordings). We started by scanning the dataset using Kaleidoscope Pro (species detected in 417 recordings), then we used BirdNET on the remaining recordings without confirmed presence. The two-step approach reduced the scanning time, the time needed for output verification, and added 37 additional species detections in 45 minutes. Our findings highlight that combining machine learning tools can improve species detectability while minimizing time and effort.
{"title":"Combining two user-friendly machine learning tools increases species detection from acoustic recordings","authors":"Cristian Pérez-Granados, Mariano J. Feldman, Marc J. Mazerolle","doi":"10.1139/cjz-2023-0154","DOIUrl":"https://doi.org/10.1139/cjz-2023-0154","url":null,"abstract":"Passive acoustic monitoring usually generates large datasets that require machine learning algorithms to scan sound files, although the complexity of developing machine learning algorithms can be a barrier. We assessed the ability and speed of two user-friendly machine learning tools, Kaleidoscope Pro and BirdNET, for detecting the American toad (Anaxyrus americanus, (Holbrook, 1836)) in sound recordings. We developed a two-step approach combining both tools to maximize species detection while minimizing the time needed for output verification. When considered separately, Kaleidoscope Pro successfully detected the American toad in 85.9% of recordings in the validation dataset, while BirdNET detected the species in 58.4% of recordings. Combining the two tools in the two-step approach increased the detection rate to 93.3%. We applied the two-step approach to a large acoustic dataset (n = 6,194 recordings). We started by scanning the dataset using Kaleidoscope Pro (species detected in 417 recordings), then we used BirdNET on the remaining recordings without confirmed presence. The two-step approach reduced the scanning time, the time needed for output verification, and added 37 additional species detections in 45 minutes. Our findings highlight that combining machine learning tools can improve species detectability while minimizing time and effort.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135589566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Brendan Carswell, Sean P Boyle, Ryan K. Brook, Floris M van Beest, Eric Vander Wal
Interactions between sympatric species influence the ecology and behaviour of individuals and species. Invasive species can often alter community dynamics by generating novel pressures that native species are less able to respond to. The scope of these pressures may depend on the ecology and life history of the invasive species. We used remote camera traps to investigate how native mammals spatiotemporal activity patterns were altered by the presence of invasive wild pig (Sus scrofa Linnaeus, 1758). By analyzing patterns of daily activity and implementing Cox proportional hazard models, our results suggest (a) that temporal partitioning may play a role in ameliorating competition between native mammals and wild pigs and (b) native species may be avoiding wild pigs by prolonging their return times to particular sites. We provide an example for monitoring the ecological changes wild pigs may create within ecosystems as they become more abundant in non-traditional ranges.
{"title":"Variation in spatiotemporal activity may reduce competitive interactions between invasive wild pigs (Sus scrofa) and native mammal species","authors":"Brendan Carswell, Sean P Boyle, Ryan K. Brook, Floris M van Beest, Eric Vander Wal","doi":"10.1139/cjz-2022-0145","DOIUrl":"https://doi.org/10.1139/cjz-2022-0145","url":null,"abstract":"Interactions between sympatric species influence the ecology and behaviour of individuals and species. Invasive species can often alter community dynamics by generating novel pressures that native species are less able to respond to. The scope of these pressures may depend on the ecology and life history of the invasive species. We used remote camera traps to investigate how native mammals spatiotemporal activity patterns were altered by the presence of invasive wild pig (Sus scrofa Linnaeus, 1758). By analyzing patterns of daily activity and implementing Cox proportional hazard models, our results suggest (a) that temporal partitioning may play a role in ameliorating competition between native mammals and wild pigs and (b) native species may be avoiding wild pigs by prolonging their return times to particular sites. We provide an example for monitoring the ecological changes wild pigs may create within ecosystems as they become more abundant in non-traditional ranges.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"18 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135589270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eric Gese, Cole A. Bleke, Shane B. Roberts, Paul Atwood, Pat Terletzky
Density-independent and density-dependent population regulation has long been a subject of investigation. We examined density-dependent and density-independent factors on growth rates of pronghorn (Antilocapra americana (Ord, 1815)) using a retrospective analysis of population survey data. Across Idaho, we found as the proportion of the subpopulation harvested the previous year increased, growth rates increased. Similarly, as fawn recruitment increased, growth rates increased. We also found when the growth rate in the previous year increased, the growth rate the subsequent year decreased. When subpopulations were examined independently, we found in a low-elevation desert subpopulation, growth rates were influenced by growth the previous year. In an agricultural-dominated site, growth rates were influenced by fawn recruitment in the current year and maximum temperature the previous fall. Growth rates in a mid-elevation shrub-steppe site were influenced by drought severity prior to parturition and the growth rates from the previous year. Growth rates in two mountain valley subpopulations were influenced by measures of vegetative greenness. At the statewide scale, while managers may strive for increased numbers of pronghorn, density dependence will limit the ability for a region-wide numerical response. On the localized scale, drivers of growth were temporally and spatially-explicit, and biologists must consider site-specific actions.
{"title":"Population growth rates of pronghorn: influence of temporally and spatially explicit conditions, density dependence, and scale","authors":"Eric Gese, Cole A. Bleke, Shane B. Roberts, Paul Atwood, Pat Terletzky","doi":"10.1139/cjz-2023-0113","DOIUrl":"https://doi.org/10.1139/cjz-2023-0113","url":null,"abstract":"Density-independent and density-dependent population regulation has long been a subject of investigation. We examined density-dependent and density-independent factors on growth rates of pronghorn (Antilocapra americana (Ord, 1815)) using a retrospective analysis of population survey data. Across Idaho, we found as the proportion of the subpopulation harvested the previous year increased, growth rates increased. Similarly, as fawn recruitment increased, growth rates increased. We also found when the growth rate in the previous year increased, the growth rate the subsequent year decreased. When subpopulations were examined independently, we found in a low-elevation desert subpopulation, growth rates were influenced by growth the previous year. In an agricultural-dominated site, growth rates were influenced by fawn recruitment in the current year and maximum temperature the previous fall. Growth rates in a mid-elevation shrub-steppe site were influenced by drought severity prior to parturition and the growth rates from the previous year. Growth rates in two mountain valley subpopulations were influenced by measures of vegetative greenness. At the statewide scale, while managers may strive for increased numbers of pronghorn, density dependence will limit the ability for a region-wide numerical response. On the localized scale, drivers of growth were temporally and spatially-explicit, and biologists must consider site-specific actions.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"79 S50","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maria Celeste Yuvero, Maria Eugenia Torroglosa, Betina J. Lomovasky, Juliana Gimenez
The size at first maturity of the bivalve Mytilus platensis d’Orbigny, 1842 was estimated in the intertidal population of Villa Gesell (37° 15'S; 56° 57'W), Buenos Aires, Argentina. We hypothesize a variation in population maturity associated with shell length (SL) and differences between females and males. Individuals were analyzed histologically, sexed (females and males), and classified as mature and immature. We carried out a Kernel Density Estimation (KDE) to allow us to visualize the distribution of the classifications based on the SL and used a Generalized Linear Model (GLM) to study the size at first sexual maturity for the population and between sexes. Our results showed immature specimens with reduced development in acini and expanded connective tissue. Mature males and females showed the acini expanded and filled with vitellogenic oocytes and spermatozoa, respectively. The size at first sexual maturity at which 50% of the population was mature (SL50) was 11.80 mm SL for all population, while SL50 was 11.42 mm in females and 10.83 mm in males. We determined significant interaction between SL and sex (p < 0.05). We conclude that the knowledge of the reproductive aspects in intertidal populations is essential for the development of a potential fishing resource.
在比耶斯尔(37°15'S)潮间带种群中测定了1842年双壳贝贻贝(Mytilus platensis d 'Orbigny, 1842)初成熟时的大小;西经56°57′，阿根廷布宜诺斯艾利斯。我们假设种群成熟度的变化与壳长(SL)和雌雄之间的差异有关。对个体进行组织学、性别(雌性和雄性)分析，并将其分为成熟和不成熟。我们进行了核密度估计(KDE)，使我们能够可视化基于SL的分类分布，并使用广义线性模型(GLM)来研究群体和性别之间的初次性成熟大小。我们的结果显示，未成熟标本的腺泡发育减少，结缔组织扩大。成熟雄性和雌性的腺泡分别扩大，充满卵黄细胞和精子。50%种群成熟时的初次性成熟尺寸(SL50)为11.80 mm SL，而雌性SL50为11.42 mm，雄性SL50为10.83 mm。我们发现SL和性别之间存在显著的相互作用(p <0.05)。我们的结论是，了解潮间带种群的生殖方面的知识对于开发潜在的渔业资源是必不可少的。
{"title":"Size at first maturity on the mussel Mytilus platensis d’Orbigny, 1842 at the Southwest Atlantic","authors":"Maria Celeste Yuvero, Maria Eugenia Torroglosa, Betina J. Lomovasky, Juliana Gimenez","doi":"10.1139/cjz-2023-0070","DOIUrl":"https://doi.org/10.1139/cjz-2023-0070","url":null,"abstract":"The size at first maturity of the bivalve Mytilus platensis d’Orbigny, 1842 was estimated in the intertidal population of Villa Gesell (37° 15'S; 56° 57'W), Buenos Aires, Argentina. We hypothesize a variation in population maturity associated with shell length (SL) and differences between females and males. Individuals were analyzed histologically, sexed (females and males), and classified as mature and immature. We carried out a Kernel Density Estimation (KDE) to allow us to visualize the distribution of the classifications based on the SL and used a Generalized Linear Model (GLM) to study the size at first sexual maturity for the population and between sexes. Our results showed immature specimens with reduced development in acini and expanded connective tissue. Mature males and females showed the acini expanded and filled with vitellogenic oocytes and spermatozoa, respectively. The size at first sexual maturity at which 50% of the population was mature (SL50) was 11.80 mm SL for all population, while SL50 was 11.42 mm in females and 10.83 mm in males. We determined significant interaction between SL and sex (p < 0.05). We conclude that the knowledge of the reproductive aspects in intertidal populations is essential for the development of a potential fishing resource.
","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"83 1‐4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hugo Guzmán Intzin, Carmen Alejo-Plata, Miguel Angel del Rio Portilla, Saúl Serrano Guzmán, Pedro Cervantes-Hernández
Squid Lolliguncula panamensis (Hoyle, 1904) is of commercial and ecological importance in the Gulf of Tehuantepec (southeastern Mexico). This study examines the mode of oocyte development, packing in the ovary, and spawning pattern of this understudied species. L. panamensis presents a synchronous oocyte growth in batches, with multiple spawning, with the presence of post-ovulatory follicles and atretic follicles, including the constant presence of pre-vitellogenic and vitellogenic oocytes. The size frequencies of oocytes of ripe ovaries exhibit a pronounced morphological and size separation between the late yolk stage and mature oocytes, suggesting that the oocytes pass through this size range very fast. These oocytes adopt a geometrical shape that makes their packing efficient for spawning. One three-dimensional packing of vitellogenic oocytes (scutoid type) in the ovary was observed. The results of our study suggest that the spawning behavior of L. panamensis may constitute an opportunistic reproductive strategy in which individuals present multiple spawning over a brief period. We suggest that this strategy might be a response to complex regional oceanographic conditions of the Gulf of Tehuantepec.
{"title":"Oocyte development, packing in the ovary, and spawning pattern of squid Lolliguncula panamensis in the Mexican South Pacific","authors":"Hugo Guzmán Intzin, Carmen Alejo-Plata, Miguel Angel del Rio Portilla, Saúl Serrano Guzmán, Pedro Cervantes-Hernández","doi":"10.1139/cjz-2023-0124","DOIUrl":"https://doi.org/10.1139/cjz-2023-0124","url":null,"abstract":"Squid Lolliguncula panamensis (Hoyle, 1904) is of commercial and ecological importance in the Gulf of Tehuantepec (southeastern Mexico). This study examines the mode of oocyte development, packing in the ovary, and spawning pattern of this understudied species. L. panamensis presents a synchronous oocyte growth in batches, with multiple spawning, with the presence of post-ovulatory follicles and atretic follicles, including the constant presence of pre-vitellogenic and vitellogenic oocytes. The size frequencies of oocytes of ripe ovaries exhibit a pronounced morphological and size separation between the late yolk stage and mature oocytes, suggesting that the oocytes pass through this size range very fast. These oocytes adopt a geometrical shape that makes their packing efficient for spawning. One three-dimensional packing of vitellogenic oocytes (scutoid type) in the ovary was observed. The results of our study suggest that the spawning behavior of L. panamensis may constitute an opportunistic reproductive strategy in which individuals present multiple spawning over a brief period. We suggest that this strategy might be a response to complex regional oceanographic conditions of the Gulf of Tehuantepec.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135808265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Grégory Bulté, Jessica A. Robichaud, Erika J. Shadlock, Steven J. Cooke, Gabriel Blouin-Demers
Mass mortality events appear to be increasing in intensity and frequency, so understanding their causes and consequences is imperative for wildlife conservation. We report on a mass mortality event in a population of Northern Map Turtles ( Graptemys geographica (LeSueur, 1817)). At a communal overwintering site, 142 carcasses (ca. 10% of population) were recovered, seemingly depredated by river otters ( Lontra canadensis (Schreber, 1777)). We compared the size and sex of the carcasses to those of turtles that survived. Smaller turtles and males were more likely to be depredated than larger turtles and females. Using captures made at the same overwintering site between 2003 and 2022, we assessed the vulnerability of this population to mass mortality events during winter. Nearly 60% of the 1875 turtles marked between 2003 and 2022 used the overwintering site where the mass mortality event occurred at least once. On average, turtles overwintered at the site at least 38% of the winters between their first and last capture. Our study shows how behaviour and physiology interact to predispose a species to mass mortality events and ecological traps. Protecting overwintering sites and minimizing human pressures affecting winter depredation may be essential for the preservation of certain turtle populations.
{"title":"Overwintering site fidelity and communal hibernation predispose Northern Map Turtles to mass mortality events","authors":"Grégory Bulté, Jessica A. Robichaud, Erika J. Shadlock, Steven J. Cooke, Gabriel Blouin-Demers","doi":"10.1139/cjz-2023-0127","DOIUrl":"https://doi.org/10.1139/cjz-2023-0127","url":null,"abstract":"Mass mortality events appear to be increasing in intensity and frequency, so understanding their causes and consequences is imperative for wildlife conservation. We report on a mass mortality event in a population of Northern Map Turtles ( Graptemys geographica (LeSueur, 1817)). At a communal overwintering site, 142 carcasses (ca. 10% of population) were recovered, seemingly depredated by river otters ( Lontra canadensis (Schreber, 1777)). We compared the size and sex of the carcasses to those of turtles that survived. Smaller turtles and males were more likely to be depredated than larger turtles and females. Using captures made at the same overwintering site between 2003 and 2022, we assessed the vulnerability of this population to mass mortality events during winter. Nearly 60% of the 1875 turtles marked between 2003 and 2022 used the overwintering site where the mass mortality event occurred at least once. On average, turtles overwintered at the site at least 38% of the winters between their first and last capture. Our study shows how behaviour and physiology interact to predispose a species to mass mortality events and ecological traps. Protecting overwintering sites and minimizing human pressures affecting winter depredation may be essential for the preservation of certain turtle populations.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"252 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136019135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Metabolic rate is a key parameter in fish energy budgets that strongly influences the output of bioenergetics models. In this study, we tested the hypothesis that metabolic rate varies with growth history of age-1 largemouth bass Micropterus nigricans Cuvier, 1828. Two groups of fish were fed alternating maintenance or ad libitum rations of fathead minnow Pimephales promelas Rafinesque, 1820, so that over a 9-week period, initial and ending size of fish was similar. After 9 weeks, oxygen consumption was measured using static, closed respirometry. Although final body weight was similar between the two groups (means, 104–108 g), specific oxygen consumption for fish fed maintenance rations (0.094 mg O 2 g −2 h −1 ) was 38% less than that measured for fish fed ad libitum (0.152 mg O 2 g −2 h −1 ). Bioenergetics estimates of food consumption were similar to observed values for fish fed ad libitum (∼7% error), but for fish fed maintenance rations, the model overestimated food consumption by 65%. By accounting for changes in metabolic rate owing to reduced feeding, error in model estimates of food consumption was reduced. These findings shed new insight into factors associated with consumption-dependent error in bioenergetics models and highlight the importance of feeding history on metabolic rate of fish. Incorporating growth-dependent metabolism into bioenergetics models can improve model accuracy and allow fisheries biologists to make more informed decisions regarding fish growth and energetics.
代谢率是鱼类能量收支的一个关键参数，它强烈影响生物能量模型的输出。在这项研究中，我们验证了1岁大口黑鲈Micropterus nigricans (Cuvier, 1828)的代谢率随生长历史变化的假设。两组鱼交替饲喂1820年黑头鲦鱼(Pimephales promelas Rafinesque, 1820)维持或随意饲料，在9周的时间内，鱼的初始和最终尺寸相似。9周后，用静态闭式呼吸仪测量耗氧量。尽管两组鱼的最终体重相似(平均值为104-108 g)，但维持饲料的比耗氧量(0.094 mg O 2 g−2 h−1)比自由饲料的比耗氧量(0.152 mg O 2 g−2 h−1)少38%。食物消耗的生物能量估计值与观察到的自由饲料鱼的值相似(误差约7%)，但对于维持饲料鱼，该模型高估了65%的食物消耗。通过考虑由于摄食减少而引起的代谢率变化，减少了模型估计食物消耗的误差。这些发现为生物能量学模型中与消耗依赖误差相关的因素提供了新的见解，并强调了饲养历史对鱼类代谢率的重要性。将生长依赖性代谢纳入生物能量学模型可以提高模型的准确性，并允许渔业生物学家对鱼类生长和能量学做出更明智的决定。
{"title":"Effect of feeding history on metabolic rate of largemouth bass (<i>Micropterus nigricans</i>): implications for bioenergetics models","authors":"Steven H. Ranney, Steven R. Chipps, David H. Wahl","doi":"10.1139/cjz-2023-0047","DOIUrl":"https://doi.org/10.1139/cjz-2023-0047","url":null,"abstract":"Metabolic rate is a key parameter in fish energy budgets that strongly influences the output of bioenergetics models. In this study, we tested the hypothesis that metabolic rate varies with growth history of age-1 largemouth bass Micropterus nigricans Cuvier, 1828. Two groups of fish were fed alternating maintenance or ad libitum rations of fathead minnow Pimephales promelas Rafinesque, 1820, so that over a 9-week period, initial and ending size of fish was similar. After 9 weeks, oxygen consumption was measured using static, closed respirometry. Although final body weight was similar between the two groups (means, 104–108 g), specific oxygen consumption for fish fed maintenance rations (0.094 mg O 2 g −2 h −1 ) was 38% less than that measured for fish fed ad libitum (0.152 mg O 2 g −2 h −1 ). Bioenergetics estimates of food consumption were similar to observed values for fish fed ad libitum (∼7% error), but for fish fed maintenance rations, the model overestimated food consumption by 65%. By accounting for changes in metabolic rate owing to reduced feeding, error in model estimates of food consumption was reduced. These findings shed new insight into factors associated with consumption-dependent error in bioenergetics models and highlight the importance of feeding history on metabolic rate of fish. Incorporating growth-dependent metabolism into bioenergetics models can improve model accuracy and allow fisheries biologists to make more informed decisions regarding fish growth and energetics.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136318664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rohab Batool, Juriyah Jenan, Madeline Schuster, Rosalind L Murray
As temperatures warm in response to anthropogenic changes (climate change and urbanization), animals must respond adaptively to these changes or be displaced. Here, we use community science data (iNaturalist and BugGuide) to show that melanisation in larval monarch butterflies (Danaus plexippus (Linnaeus, 1758)); an endangered species in Canada) is correlated with latitude and temperature across a latitudinal gradient, indicating likely use in thermoregulation. We also predicted that melanisation would decrease in cities where temperatures are consistently higher than rural areas, however we found that while melanisation was lower in urban areas, it was not statistically significant. Our results demonstrate the importance of considering life stage when assessing capacity for adaptation to anthropogenic change in vulnerable animal populations, like monarch butterflies. We also show the value of using community science to sample species (particular those of most concern) distributions across the landscape.
{"title":"How do latitude and urban heat islands affect monarch butterfly (Danaus plexippus) larval melanisation?","authors":"Rohab Batool, Juriyah Jenan, Madeline Schuster, Rosalind L Murray","doi":"10.1139/cjz-2023-0099","DOIUrl":"https://doi.org/10.1139/cjz-2023-0099","url":null,"abstract":"As temperatures warm in response to anthropogenic changes (climate change and urbanization), animals must respond adaptively to these changes or be displaced. Here, we use community science data (iNaturalist and BugGuide) to show that melanisation in larval monarch butterflies (Danaus plexippus (Linnaeus, 1758)); an endangered species in Canada) is correlated with latitude and temperature across a latitudinal gradient, indicating likely use in thermoregulation. We also predicted that melanisation would decrease in cities where temperatures are consistently higher than rural areas, however we found that while melanisation was lower in urban areas, it was not statistically significant. Our results demonstrate the importance of considering life stage when assessing capacity for adaptation to anthropogenic change in vulnerable animal populations, like monarch butterflies. We also show the value of using community science to sample species (particular those of most concern) distributions across the landscape.","PeriodicalId":9484,"journal":{"name":"Canadian Journal of Zoology","volume":"10 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135218002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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