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Qué

Picogrueso Norteño (Coccothraustes vespertinus)

Autor

elisemaclean

Fecha

Octubre 8, 2016 a las 08:19 PM EDT

Descripción

Introduction

The Coccothraustes vespertinus, also known as Evening Grosbeaks, belong to the Fringillidae family. The males are known to have a black head and yellow forehead with a brownish yellow abdomen, as pictured above (Gillihan & Byers, 2001). The following report discusses the main characteristics of these birds.

Habitat and Geographic Range

This species is a Northern American bird and can be viewed from east to west in both the United States and Canada. More specifically in Canada, these birds can found from eastern and southern British Columbia all the way to the southern half of Newfoundland (Gillihan & Byers, 2001). Occasionally, there have been sightings of the Evening Grosbeaks in Mexico as well as Norway and Scotland. In the majority of breeding areas, these birds are a year round resident although they have also been found to leave northern areas during winter (Gillihan & Byers, 2001). Historically, the Evening Grosbeaks were only in the western states and provinces but due to the planting of many box elder trees in both the prairies and north eastern cities, these birds have expanded to the east (Forbush, 1929). This North American bird tends to reside in both coniferous and mixed forests during breeding season. These forests can contain many different types of tress such as: pine trees, spruce, fir, oak and juniper. During winter, the Evening Grosbeak’s habitat includes coniferous and deciduous forests as well as urban and suburban areas (Gillihan & Byers, 2001). These birds also have various microhabitat characteristics when deciding where to build their nests. Some of these requirements are openness, a southern orientation, and large trees (Bekoff et al., 1989).
Typical Size, Weight and Lifespan
The Evening Grosbeaks are a relatively large finch, with their overall length ranging from 175-215mm (Forbush, 1929). The males have a wing length of approximately 111.3 mm whereas the females have a wing length of 108.1 mm. In terms of weight, the males typically have larger bodies than the females with males weighing 61.8 grams and the females weighing at 61.0 grams (Prescott, 1994; Shaub & Shaub, 1950). The average lifespan of these birds is estimated to be around 15 years (Gillihan & Byers, 2001).

Diet

The main diet of the Evening Grosbeaks contains invertebrates, small fruits and seeds. Some common invertebrates include: caterpillars, beetles, spruce budworms and aphids. These birds will also consume a variety of seeds from trees, forbs and shrubs (Gillihan & Byers, 2001). In terms of small fruits, these skilled birds particularly like the pit or the seeds within the fruit themselves (Shaub, 1956). Evening Grosbeaks are unique birds as they are attracted to both salt and mineral rich soil and will also eat charcoal and coal (Gillihan & Byers, 2001; Orr, 1951).
Reproduction and Communication
Four weeks prior to breeding, large flocks of Evening Grosbeaks will dissipate into smaller groups and eventually form monogamous pairs (Bekoff & Scott, 1991). In May, these males tend to begin courtship by feeding the female and offering seeds to her (Gillihan & Byers, 2001). In a study conducted by Bekoff and Scott, the three most common behaviours observed during courtship include wing flutter, calls from perch and wing droop (1991). Immediately after landing on breeding grounds, nest construction begins. In mid May, the females will typically lay one egg per day and have a clutch size anywhere from 2-5 eggs. The incubation period lasts 12-14 days and then after hatching the parents will brood their young for approximately 14 days. After the brooding period, the young bird or fledgling will leave the nest around 14 days of age however these fledglings will continue to keep in contact with their parents (Gillihan & Byers, 2001). In terms of parenting, the females had the task of building the nest, incubating, brooding and feeding the young. On the other hand, the males participated in both feeding and protecting the young. Both sexes equally contributed to both soft calling as well as fecal removal. Overall, it was observed that Evening Grosbeaks form a partnership whereby the roles and effort involved are divided amongst the parents (Bekoff & Scott, 1991). In terms of other types of communication, several behaviours were observed such as threat displays, appeasement behaviour and agonistic behaviours (Gillihan & Byers, 2001).

Predation

The Evening Grosbeak has many predators some of which include domestic cats, Sharp-shinned hawk, Cooper’s hawk, Northern goshawk, Northern pygmy-owl and the Northern shrike. Additionally, the specific predator that targets the eggs of these birds is the common raven (Gillihan & Byers, 2001). According to Bekoff, during the nonbreeding season, Evening Grosbeaks will spend a greater amount of time in flocks to increase the scanning for predators (1995). When a predator is spotted, these birds are known to produce an alarm call to warn the others (Bekoff, 1995). In the presence of a predator females are more likely to remain motionless whereas the males will fly to cover (Balph, 1977).

Conservation Status

According to the IUCN, the conservation status of the Evening Grosbeaks is of least concern and in Canada the status given is also stated as secure (International Union for Conservation of Nature and Natural Resources, 2012; The Government of Canada, 2011). Despite these secure statuses mentioned above, there has been a significant decrease in the population of these birds (Bonter & Harvey, 2008). It is suspected that the cause of this population decline is due to forestry operations that are destroying and altering the habitats of these birds.

Did you know?

1) The Evening Grosbeak was mistakenly named due to the belief that the species sang only in the evening (Gillihan & Byers, 2001).
2) The Evening Grosbeak can break open food items that would need approximately 125 pounds of pressure to crack in the laboratory (Gillihan & Byers, 2001).
3) Evening Grosbeaks enjoy drinking the sap off of trees by snapping the wigs off of Sugar Maple Trees (Gillihan & Byers, 2001).

Works Cited

Balph, M. H. (1977). Sex differences in alarm responses of wintering Evening Grosbeaks. The Wilson Bulletin, 89(2), 325-327.

Bekoff, M. (1995). Vigilance, flock size, and flock geometry: information gathering by western evening grosbeaks (Aves, Fringillidae). Ethology, 99(1‐2), 150-161.

Bekoff, M., Scott, A. C., & Conner, D. A. (1989). Ecological analyses of nesting success in evening grosbeaks. Oecologia, 81(1), 67-74.

BirdLife International. 2012. Coccothraustes vespertinus. The IUCN Red List of Threatened Species 2012: e.T22720702A39828945. Retrieved from: http://dx.doi.org/10.2305/IUCN.UK.2012-1.RLTS.T22720702A39828945.en.

Bonter, D. N., & Harvey, M. G. (2008). Winter survey data reveal rangewide decline in Evening Grosbeak populations. The Condor, 110(2), 376-381.

Forbush, E. H. (1929). Birds of Massachusetts and other New England states. Vol. 3. Boston, Massachusetts Dept. Agriculture. xlviii.

Gillihan, S.W., & Byers, B. (2001). Evening Grosbeak (Coccothraustes vespertinus), The Birds of North America (P. G. Rodewald, Ed.). Cornell Lab of Ornithology. DOI: 10.2173/bna.599
Retrieved from: https://birdsna.org/Species-Account/bna/species/evegro

Government of Canada. (2015). Evening Grosbeak (Coccothraustes vespertinus). Retrieved from: http://www.ec.gc.ca/soc-sbc/oiseau-bird-eng.aspx?sY=2011&sL=e&sM=p1&sB=EVGR#ref276

Orr, R. T. (1951). Observations on the birds of northeastern Idaho (Vol. 27, No. 1).

Prescott, D. R. (1994). Intraspecific and geographical trends in body size of a differential migrant, the evening grosbeak. The Auk, 693-702.

Scott, A. C., & Bekoff, M. (1991). Breeding behavior of evening grosbeaks. Condor, 71-81.

Shaub, B. M., & Shaub, M. S. (1950). Weight Variation of the Evening Grosbeak at Northampton, Massachusetts from January to May 1949. Bird-Banding, 139-145.

Shaub, M. S. (1956). Eastern Evening Grosbeak Summer Records: Part I Survey of New Brunswick, New England and New York, 1954 and 1955. Bird-Banding, 157-165.

Fotos / Sonidos

Qué

Picogrueso Norteño (Coccothraustes vespertinus)

Autor

elisemaclean

Fecha

Octubre 8, 2016 a las 08:19 PM EDT

Descripción

Introduction

The Coccothraustes vespertinus, also known as Evening Grosbeaks, belong to the Fringillidae family. The males are known to have a black head and yellow forehead with a brownish yellow abdomen, as pictured above (Gillihan & Byers, 2001). The following report discusses the main characteristics of these birds.

Habitat and Geographic Range

This species is a Northern American bird and can be viewed from east to west in both the United States and Canada. More specifically in Canada, these birds can found from eastern and southern British Columbia all the way to the southern half of Newfoundland (Gillihan & Byers, 2001). Occasionally, there have been sightings of the Evening Grosbeaks in Mexico as well as Norway and Scotland. In the majority of breeding areas, these birds are a year round resident although they have also been found to leave northern areas during winter (Gillihan & Byers, 2001). Historically, the Evening Grosbeaks were only in the western states and provinces but due to the planting of many box elder trees in both the prairies and north eastern cities, these birds have expanded to the east (Forbush, 1929). This North American bird tends to reside in both coniferous and mixed forests during breeding season. These forests can contain many different types of tress such as: pine trees, spruce, fir, oak and juniper. During winter, the Evening Grosbeak’s habitat includes coniferous and deciduous forests as well as urban and suburban areas (Gillihan & Byers, 2001). These birds also have various microhabitat characteristics when deciding where to build their nests. Some of these requirements are openness, a southern orientation, and large trees (Bekoff et al., 1989).
Typical Size, Weight and Lifespan
The Evening Grosbeaks are a relatively large finch, with their overall length ranging from 175-215mm (Forbush, 1929). The males have a wing length of approximately 111.3 mm whereas the females have a wing length of 108.1 mm. In terms of weight, the males typically have larger bodies than the females with males weighing 61.8 grams and the females weighing at 61.0 grams (Prescott, 1994; Shaub & Shaub, 1950). The average lifespan of these birds is estimated to be around 15 years (Gillihan & Byers, 2001).

Diet

The main diet of the Evening Grosbeaks contains invertebrates, small fruits and seeds. Some common invertebrates include: caterpillars, beetles, spruce budworms and aphids. These birds will also consume a variety of seeds from trees, forbs and shrubs (Gillihan & Byers, 2001). In terms of small fruits, these skilled birds particularly like the pit or the seeds within the fruit themselves (Shaub, 1956). Evening Grosbeaks are unique birds as they are attracted to both salt and mineral rich soil and will also eat charcoal and coal (Gillihan & Byers, 2001; Orr, 1951).

Reproduction and Communication

Four weeks prior to breeding, large flocks of Evening Grosbeaks will dissipate into smaller groups and eventually form monogamous pairs (Bekoff & Scott, 1991). In May, these males tend to begin courtship by feeding the female and offering seeds to her (Gillihan & Byers, 2001). In a study conducted by Bekoff and Scott, the three most common behaviours observed during courtship include wing flutter, calls from perch and wing droop (1991). Immediately after landing on breeding grounds, nest construction begins. In mid May, the females will typically lay one egg per day and have a clutch size anywhere from 2-5 eggs. The incubation period lasts 12-14 days and then after hatching the parents will brood their young for approximately 14 days. After the brooding period, the young bird or fledgling will leave the nest around 14 days of age however these fledglings will continue to keep in contact with their parents (Gillihan & Byers, 2001). In terms of parenting, the females had the task of building the nest, incubating, brooding and feeding the young. On the other hand, the males participated in both feeding and protecting the young. Both sexes equally contributed to both soft calling as well as fecal removal. Overall, it was observed that Evening Grosbeaks form a partnership whereby the roles and effort involved are divided amongst the parents (Bekoff & Scott, 1991). In terms of other types of communication, several behaviours were observed such as threat displays, appeasement behaviour and agonistic behaviours (Gillihan & Byers, 2001).

Predation

The Evening Grosbeak has many predators some of which include domestic cats, Sharp-shinned hawk, Cooper’s hawk, Northern goshawk, Northern pygmy-owl and the Northern shrike. Additionally, the specific predator that targets the eggs of these birds is the common raven (Gillihan & Byers, 2001). According to Bekoff, during the nonbreeding season, Evening Grosbeaks will spend a greater amount of time in flocks to increase the scanning for predators (1995). When a predator is spotted, these birds are known to produce an alarm call to warn the others (Bekoff, 1995). In the presence of a predator females are more likely to remain motionless whereas the males will fly to cover (Balph, 1977).

Conservation Status

According to the IUCN, the conservation status of the Evening Grosbeaks is of least concern and in Canada the status given is also stated as secure (International Union for Conservation of Nature and Natural Resources, 2012; The Government of Canada, 2011). Despite these secure statuses mentioned above, there has been a significant decrease in the population of these birds (Bonter & Harvey, 2008). It is suspected that the cause of this population decline is due to forestry operations that are destroying and altering the habitats of these birds.

Did you know?

1) The Evening Grosbeak was mistakenly named due to the belief that the species sang only in the evening (Gillihan & Byers, 2001).
2) The Evening Grosbeak can break open food items that would need approximately 125 pounds of pressure to crack in the laboratory (Gillihan & Byers, 2001).
3) Evening Grosbeaks enjoy drinking the sap off of trees by snapping the wigs off of Sugar Maple Trees (Gillihan & Byers, 2001).

Works Cited

Balph, M. H. (1977). Sex differences in alarm responses of wintering Evening Grosbeaks. The Wilson Bulletin, 89(2), 325-327.

Bekoff, M. (1995). Vigilance, flock size, and flock geometry: information gathering by western evening grosbeaks (Aves, Fringillidae). Ethology, 99(1‐2), 150-161.

Bekoff, M., Scott, A. C., & Conner, D. A. (1989). Ecological analyses of nesting success in evening grosbeaks. Oecologia, 81(1), 67-74.

BirdLife International. 2012. Coccothraustes vespertinus. The IUCN Red List of Threatened Species 2012: e.T22720702A39828945. Retrieved from: http://dx.doi.org/10.2305/IUCN.UK.2012-1.RLTS.T22720702A39828945.en.

Bonter, D. N., & Harvey, M. G. (2008). Winter survey data reveal rangewide decline in Evening Grosbeak populations. The Condor, 110(2), 376-381.

Forbush, E. H. (1929). Birds of Massachusetts and other New England states. Vol. 3. Boston, Massachusetts Dept. Agriculture. xlviii.

Gillihan, S.W., & Byers, B. (2001). Evening Grosbeak (Coccothraustes vespertinus), The Birds of North America (P. G. Rodewald, Ed.). Cornell Lab of Ornithology. DOI: 10.2173/bna.599
Retrieved from: https://birdsna.org/Species-Account/bna/species/evegro

Government of Canada. (2015). Evening Grosbeak (Coccothraustes vespertinus). Retrieved from: http://www.ec.gc.ca/soc-sbc/oiseau-bird-eng.aspx?sY=2011&sL=e&sM=p1&sB=EVGR#ref276

Orr, R. T. (1951). Observations on the birds of northeastern Idaho (Vol. 27, No. 1).

Prescott, D. R. (1994). Intraspecific and geographical trends in body size of a differential migrant, the evening grosbeak. The Auk, 693-702.

Scott, A. C., & Bekoff, M. (1991). Breeding behavior of evening grosbeaks. Condor, 71-81.

Shaub, B. M., & Shaub, M. S. (1950). Weight Variation of the Evening Grosbeak at Northampton, Massachusetts from January to May 1949. Bird-Banding, 139-145.

Shaub, M. S. (1956). Eastern Evening Grosbeak Summer Records: Part I Survey of New Brunswick, New England and New York, 1954 and 1955. Bird-Banding, 157-165.

Fotos / Sonidos

Qué

Picogrueso Norteño (Coccothraustes vespertinus)

Autor

elisemaclean

Fecha

Octubre 8, 2016 a las 08:19 PM EDT

Descripción

Introduction

The Coccothraustes vespertinus, also known as Evening Grosbeaks, belong to the Fringillidae family. The males are known to have a black head and yellow forehead with a brownish yellow abdomen, as pictured above (Gillihan & Byers, 2001). The following report discusses the main characteristics of these birds.

Habitat and Geographic Range

This species is a Northern American bird and can be viewed from east to west in both the United States and Canada. More specifically in Canada, these birds can found from eastern and southern British Columbia all the way to the southern half of Newfoundland (Gillihan & Byers, 2001). Occasionally, there have been sightings of the Evening Grosbeaks in Mexico as well as Norway and Scotland. In the majority of breeding areas, these birds are a year round resident although they have also been found to leave northern areas during winter (Gillihan & Byers, 2001). Historically, the Evening Grosbeaks were only in the western states and provinces but due to the planting of many box elder trees in both the prairies and north eastern cities, these birds have expanded to the east (Forbush, 1929). This North American bird tends to reside in both coniferous and mixed forests during breeding season. These forests can contain many different types of tress such as: pine trees, spruce, fir, oak and juniper. During winter, the Evening Grosbeak’s habitat includes coniferous and deciduous forests as well as urban and suburban areas (Gillihan & Byers, 2001). These birds also have various microhabitat characteristics when deciding where to build their nests. Some of these requirements are openness, a southern orientation, and large trees (Bekoff et al., 1989).
Typical Size, Weight and Lifespan
The Evening Grosbeaks are a relatively large finch, with their overall length ranging from 175-215mm (Forbush, 1929). The males have a wing length of approximately 111.3 mm whereas the females have a wing length of 108.1 mm. In terms of weight, the males typically have larger bodies than the females with males weighing 61.8 grams and the females weighing at 61.0 grams (Prescott, 1994; Shaub & Shaub, 1950). The average lifespan of these birds is estimated to be around 15 years (Gillihan & Byers, 2001).

Diet

The main diet of the Evening Grosbeaks contains invertebrates, small fruits and seeds. Some common invertebrates include: caterpillars, beetles, spruce budworms and aphids. These birds will also consume a variety of seeds from trees, forbs and shrubs (Gillihan & Byers, 2001). In terms of small fruits, these skilled birds particularly like the pit or the seeds within the fruit themselves (Shaub, 1956). Evening Grosbeaks are unique birds as they are attracted to both salt and mineral rich soil and will also eat charcoal and coal (Gillihan & Byers, 2001; Orr, 1951).

Reproduction and Communication

Four weeks prior to breeding, large flocks of Evening Grosbeaks will dissipate into smaller groups and eventually form monogamous pairs (Bekoff & Scott, 1991). In May, these males tend to begin courtship by feeding the female and offering seeds to her (Gillihan & Byers, 2001). In a study conducted by Bekoff and Scott, the three most common behaviours observed during courtship include wing flutter, calls from perch and wing droop (1991). Immediately after landing on breeding grounds, nest construction begins. In mid May, the females will typically lay one egg per day and have a clutch size anywhere from 2-5 eggs. The incubation period lasts 12-14 days and then after hatching the parents will brood their young for approximately 14 days. After the brooding period, the young bird or fledgling will leave the nest around 14 days of age however these fledglings will continue to keep in contact with their parents (Gillihan & Byers, 2001). In terms of parenting, the females had the task of building the nest, incubating, brooding and feeding the young. On the other hand, the males participated in both feeding and protecting the young. Both sexes equally contributed to both soft calling as well as fecal removal. Overall, it was observed that Evening Grosbeaks form a partnership whereby the roles and effort involved are divided amongst the parents (Bekoff & Scott, 1991). In terms of other types of communication, several behaviours were observed such as threat displays, appeasement behaviour and agonistic behaviours (Gillihan & Byers, 2001).

Predation

The Evening Grosbeak has many predators some of which include domestic cats, Sharp-shinned hawk, Cooper’s hawk, Northern goshawk, Northern pygmy-owl and the Northern shrike. Additionally, the specific predator that targets the eggs of these birds is the common raven (Gillihan & Byers, 2001). According to Bekoff, during the nonbreeding season, Evening Grosbeaks will spend a greater amount of time in flocks to increase the scanning for predators (1995). When a predator is spotted, these birds are known to produce an alarm call to warn the others (Bekoff, 1995). In the presence of a predator females are more likely to remain motionless whereas the males will fly to cover (Balph, 1977).

Conservation Status

According to the IUCN, the conservation status of the Evening Grosbeaks is of least concern and in Canada the status given is also stated as secure (International Union for Conservation of Nature and Natural Resources, 2012; The Government of Canada, 2011). Despite these secure statuses mentioned above, there has been a significant decrease in the population of these birds (Bonter & Harvey, 2008). It is suspected that the cause of this population decline is due to forestry operations that are destroying and altering the habitats of these birds.

Did you know?

1) The Evening Grosbeak was mistakenly named due to the belief that the species sang only in the evening (Gillihan & Byers, 2001).
2) The Evening Grosbeak can break open food items that would need approximately 125 pounds of pressure to crack in the laboratory (Gillihan & Byers, 2001).
3) Evening Grosbeaks enjoy drinking the sap off of trees by snapping the wigs off of Sugar Maple Trees (Gillihan & Byers, 2001).

Works Cited

Balph, M. H. (1977). Sex differences in alarm responses of wintering Evening Grosbeaks. The Wilson Bulletin, 89(2), 325-327.

Bekoff, M. (1995). Vigilance, flock size, and flock geometry: information gathering by western evening grosbeaks (Aves, Fringillidae). Ethology, 99(1‐2), 150-161.

Bekoff, M., Scott, A. C., & Conner, D. A. (1989). Ecological analyses of nesting success in evening grosbeaks. Oecologia, 81(1), 67-74.

BirdLife International. 2012. Coccothraustes vespertinus. The IUCN Red List of Threatened Species 2012: e.T22720702A39828945. Retrieved from: http://dx.doi.org/10.2305/IUCN.UK.2012-1.RLTS.T22720702A39828945.en.

Bonter, D. N., & Harvey, M. G. (2008). Winter survey data reveal rangewide decline in Evening Grosbeak populations. The Condor, 110(2), 376-381.

Forbush, E. H. (1929). Birds of Massachusetts and other New England states. Vol. 3. Boston, Massachusetts Dept. Agriculture. xlviii.

Gillihan, S.W., & Byers, B. (2001). Evening Grosbeak (Coccothraustes vespertinus), The Birds of North America (P. G. Rodewald, Ed.). Cornell Lab of Ornithology. DOI: 10.2173/bna.599
Retrieved from: https://birdsna.org/Species-Account/bna/species/evegro

Government of Canada. (2015). Evening Grosbeak (Coccothraustes vespertinus). Retrieved from: http://www.ec.gc.ca/soc-sbc/oiseau-bird-eng.aspx?sY=2011&sL=e&sM=p1&sB=EVGR#ref276

Orr, R. T. (1951). Observations on the birds of northeastern Idaho (Vol. 27, No. 1).

Prescott, D. R. (1994). Intraspecific and geographical trends in body size of a differential migrant, the evening grosbeak. The Auk, 693-702.

Scott, A. C., & Bekoff, M. (1991). Breeding behavior of evening grosbeaks. Condor, 71-81.

Shaub, B. M., & Shaub, M. S. (1950). Weight Variation of the Evening Grosbeak at Northampton, Massachusetts from January to May 1949. Bird-Banding, 139-145.

Shaub, M. S. (1956). Eastern Evening Grosbeak Summer Records: Part I Survey of New Brunswick, New England and New York, 1954 and 1955. Bird-Banding, 157-165.

Fotos / Sonidos

Qué

Picogrueso Norteño (Coccothraustes vespertinus)

Autor

elisemaclean

Fecha

Octubre 8, 2016 a las 08:19 PM EDT

Descripción

Introduction

The Coccothraustes vespertinus, also known as Evening Grosbeaks, belong to the Fringillidae family. The males are known to have a black head and yellow forehead with a brownish yellow abdomen, as pictured above (Gillihan & Byers, 2001). The following report discusses the main characteristics of these birds.

Habitat and Geographic Range

This species is a Northern American bird and can be viewed from east to west in both the United States and Canada. More specifically in Canada, these birds can found from eastern and southern British Columbia all the way to the southern half of Newfoundland (Gillihan & Byers, 2001). Occasionally, there have been sightings of the Evening Grosbeaks in Mexico as well as Norway and Scotland. In the majority of breeding areas, these birds are a year round resident although they have also been found to leave northern areas during winter (Gillihan & Byers, 2001). Historically, the Evening Grosbeaks were only in the western states and provinces but due to the planting of many box elder trees in both the prairies and north eastern cities, these birds have expanded to the east (Forbush, 1929). This North American bird tends to reside in both coniferous and mixed forests during breeding season. These forests can contain many different types of tress such as: pine trees, spruce, fir, oak and juniper. During winter, the Evening Grosbeak’s habitat includes coniferous and deciduous forests as well as urban and suburban areas (Gillihan & Byers, 2001). These birds also have various microhabitat characteristics when deciding where to build their nests. Some of these requirements are openness, a southern orientation, and large trees (Bekoff et al., 1989).
Typical Size, Weight and Lifespan
The Evening Grosbeaks are a relatively large finch, with their overall length ranging from 175-215mm (Forbush, 1929). The males have a wing length of approximately 111.3 mm whereas the females have a wing length of 108.1 mm. In terms of weight, the males typically have larger bodies than the females with males weighing 61.8 grams and the females weighing at 61.0 grams (Prescott, 1994; Shaub & Shaub, 1950). The average lifespan of these birds is estimated to be around 15 years (Gillihan & Byers, 2001).

Diet

The main diet of the Evening Grosbeaks contains invertebrates, small fruits and seeds. Some common invertebrates include: caterpillars, beetles, spruce budworms and aphids. These birds will also consume a variety of seeds from trees, forbs and shrubs (Gillihan & Byers, 2001). In terms of small fruits, these skilled birds particularly like the pit or the seeds within the fruit themselves (Shaub, 1956). Evening Grosbeaks are unique birds as they are attracted to both salt and mineral rich soil and will also eat charcoal and coal (Gillihan & Byers, 2001; Orr, 1951).

Reproduction and Communication

Four weeks prior to breeding, large flocks of Evening Grosbeaks will dissipate into smaller groups and eventually form monogamous pairs (Bekoff & Scott, 1991). In May, these males tend to begin courtship by feeding the female and offering seeds to her (Gillihan & Byers, 2001). In a study conducted by Bekoff and Scott, the three most common behaviours observed during courtship include wing flutter, calls from perch and wing droop (1991). Immediately after landing on breeding grounds, nest construction begins. In mid May, the females will typically lay one egg per day and have a clutch size anywhere from 2-5 eggs. The incubation period lasts 12-14 days and then after hatching the parents will brood their young for approximately 14 days. After the brooding period, the young bird or fledgling will leave the nest around 14 days of age however these fledglings will continue to keep in contact with their parents (Gillihan & Byers, 2001). In terms of parenting, the females had the task of building the nest, incubating, brooding and feeding the young. On the other hand, the males participated in both feeding and protecting the young. Both sexes equally contributed to both soft calling as well as fecal removal. Overall, it was observed that Evening Grosbeaks form a partnership whereby the roles and effort involved are divided amongst the parents (Bekoff & Scott, 1991). In terms of other types of communication, several behaviours were observed such as threat displays, appeasement behaviour and agonistic behaviours (Gillihan & Byers, 2001).

Predation

The Evening Grosbeak has many predators some of which include domestic cats, Sharp-shinned hawk, Cooper’s hawk, Northern goshawk, Northern pygmy-owl and the Northern shrike. Additionally, the specific predator that targets the eggs of these birds is the common raven (Gillihan & Byers, 2001). According to Bekoff, during the nonbreeding season, Evening Grosbeaks will spend a greater amount of time in flocks to increase the scanning for predators (1995). When a predator is spotted, these birds are known to produce an alarm call to warn the others (Bekoff, 1995). In the presence of a predator females are more likely to remain motionless whereas the males will fly to cover (Balph, 1977).

Conservation Status

According to the IUCN, the conservation status of the Evening Grosbeaks is of least concern and in Canada the status given is also stated as secure (International Union for Conservation of Nature and Natural Resources, 2012; The Government of Canada, 2011). Despite these secure statuses mentioned above, there has been a significant decrease in the population of these birds (Bonter & Harvey, 2008). It is suspected that the cause of this population decline is due to forestry operations that are destroying and altering the habitats of these birds.

Did you know?

1) The Evening Grosbeak was mistakenly named due to the belief that the species sang only in the evening (Gillihan & Byers, 2001).
2) The Evening Grosbeak can break open food items that would need approximately 125 pounds of pressure to crack in the laboratory (Gillihan & Byers, 2001).
3) Evening Grosbeaks enjoy drinking the sap off of trees by snapping the wigs off of Sugar Maple Trees (Gillihan & Byers, 2001).

Works Cited

Balph, M. H. (1977). Sex differences in alarm responses of wintering Evening Grosbeaks. The Wilson Bulletin, 89(2), 325-327.

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