Birds feeding on aloe nectar: do camera traps and point counts produce comparable data?
- Craig, Christie A, Hunter, Cayley, Craig, Adrian J F K, Hulley, Patrick E
- Authors: Craig, Christie A , Hunter, Cayley , Craig, Adrian J F K , Hulley, Patrick E
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465336 , vital:76595 , https://journals.uct.ac.za/index.php/BO/article/view/467/485
- Description: This paper represents a single season of camera trapping at aloes. We found that point counts recorded more species and therefore gave a broader picture of species diversity in the area. The differences between the two methods indicate caution in relying on just one method for this type of survey. Since camera traps focus on the aloes, they capture primarily birds feeding on nectar. The two methods should be regarded as complementary, since both an overview of the avifauna and the activity of individual species is important in analysing differences between seasons.
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- Authors: Craig, Christie A , Hunter, Cayley , Craig, Adrian J F K , Hulley, Patrick E
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465336 , vital:76595 , https://journals.uct.ac.za/index.php/BO/article/view/467/485
- Description: This paper represents a single season of camera trapping at aloes. We found that point counts recorded more species and therefore gave a broader picture of species diversity in the area. The differences between the two methods indicate caution in relying on just one method for this type of survey. Since camera traps focus on the aloes, they capture primarily birds feeding on nectar. The two methods should be regarded as complementary, since both an overview of the avifauna and the activity of individual species is important in analysing differences between seasons.
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Blue Cranes Anthropoides paradiseus at Etosha Pan, Namibia: what is the origin of this isolated population?
- Authors: Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465347 , vital:76596 , https://doi.org/10.25226/bboc.v137i3.2017.a4
- Description: There is an isolated breeding population of Blue Cranes Anthropoides paradiseus around Etosha Pan, in northern Namibia, despite a lack of regular reports of the species from adjoining regions of Botswana, southern Namibia or even north-western South Africa. A search for historical records of Blue Cranes north of South Africa suggests occasional vagrancy to southern Namibia, eastern Botswana and perhaps Zimbabwe, with consistent sightings of resident, breeding birds only from Etosha since 1918. It is apparently not a relict population. While the natural establishment of a breeding population by rare vagrants appears unlikely, there is no documented evidence for the alternative explanation that birds were deliberately introduced to this locality.
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- Authors: Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465347 , vital:76596 , https://doi.org/10.25226/bboc.v137i3.2017.a4
- Description: There is an isolated breeding population of Blue Cranes Anthropoides paradiseus around Etosha Pan, in northern Namibia, despite a lack of regular reports of the species from adjoining regions of Botswana, southern Namibia or even north-western South Africa. A search for historical records of Blue Cranes north of South Africa suggests occasional vagrancy to southern Namibia, eastern Botswana and perhaps Zimbabwe, with consistent sightings of resident, breeding birds only from Etosha since 1918. It is apparently not a relict population. While the natural establishment of a breeding population by rare vagrants appears unlikely, there is no documented evidence for the alternative explanation that birds were deliberately introduced to this locality.
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Cape White-eyes in the Eastern Cape: plumage characters, survival, and movements
- Craig, Adrian J F K, Galpin, Mark D, Hulley, Patrick E, Tree, Anthony J
- Authors: Craig, Adrian J F K , Galpin, Mark D , Hulley, Patrick E , Tree, Anthony J
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465358 , vital:76597 , https://journals.uct.ac.za/index.php/BO/article/view/423/464
- Description: Almost all our records of green-bellied Cape White-eyes are outside the breeding season, with a peak in winter. They possibly come from localities to the east of Grahamstown, Bathurst and Port Alfred, but we have no direct evidence of such movement, nor of altitudinal migration between coastal and inland sites. The higher frequency of green-bellied birds at the coastal ringing sites may suggest local movements within the coastal belt, or occasional coastwards movement by adjoining populations, which could also account for the diversity of flank colours recorded in a small proportion of the birds.
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- Authors: Craig, Adrian J F K , Galpin, Mark D , Hulley, Patrick E , Tree, Anthony J
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465358 , vital:76597 , https://journals.uct.ac.za/index.php/BO/article/view/423/464
- Description: Almost all our records of green-bellied Cape White-eyes are outside the breeding season, with a peak in winter. They possibly come from localities to the east of Grahamstown, Bathurst and Port Alfred, but we have no direct evidence of such movement, nor of altitudinal migration between coastal and inland sites. The higher frequency of green-bellied birds at the coastal ringing sites may suggest local movements within the coastal belt, or occasional coastwards movement by adjoining populations, which could also account for the diversity of flank colours recorded in a small proportion of the birds.
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Comparative perch selection in Southern Fiscal Lanius collaris and Fiscal Flycatcher Sigelus silens at Amakhala Game Reserve, South Africa
- Daniels, Ryan J, Hulley, Patrick E, Craig, Adrian J F K
- Authors: Daniels, Ryan J , Hulley, Patrick E , Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449294 , vital:74809 , https://doi.org/10.2989/00306525.2016.1264496
- Description: The Southern Fiscal Lanius collaris and the Fiscal Flycatcher Sigelus silens are common, widespread and sympatric in much of southern Africa. They are similar in plumage and ecology, which may predispose them to competition and interspecific territorial aggression but this has not been tested to date. Here we tested for evidence of competition for perch space. At Amakhala Private Game Reserve, Eastern Cape, South Africa we monitored the occurrence and perch use of both species along transects. The birds do co-occur locally but there is evidence of small-scale spatial separation possibly a result of interspecific territoriality. Perch selection differed in respect of perch type but not perch height. Both species perched prominently in the majority of observations. Southern Fiscals make greater use of Searsia and Gymnosporia trees, whereas the Fiscal Flycatcher makes near-equal use of Vachellia karroo, Searsia and Gymnosporia trees. This may be an example of niche partitioning, though it remains unclear whether the birds actively compete for perch space, or if the separation is a product of different perch preferences, territoriality and the local plant community.
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- Authors: Daniels, Ryan J , Hulley, Patrick E , Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449294 , vital:74809 , https://doi.org/10.2989/00306525.2016.1264496
- Description: The Southern Fiscal Lanius collaris and the Fiscal Flycatcher Sigelus silens are common, widespread and sympatric in much of southern Africa. They are similar in plumage and ecology, which may predispose them to competition and interspecific territorial aggression but this has not been tested to date. Here we tested for evidence of competition for perch space. At Amakhala Private Game Reserve, Eastern Cape, South Africa we monitored the occurrence and perch use of both species along transects. The birds do co-occur locally but there is evidence of small-scale spatial separation possibly a result of interspecific territoriality. Perch selection differed in respect of perch type but not perch height. Both species perched prominently in the majority of observations. Southern Fiscals make greater use of Searsia and Gymnosporia trees, whereas the Fiscal Flycatcher makes near-equal use of Vachellia karroo, Searsia and Gymnosporia trees. This may be an example of niche partitioning, though it remains unclear whether the birds actively compete for perch space, or if the separation is a product of different perch preferences, territoriality and the local plant community.
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Gill Memorial Medal Address 2014 Reviewing the Red Bishop: the bird that introduced me to ornithology
- Authors: Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449401 , vital:74818 , https://www.tandfonline.com/doi/pdf/10.2989/00306525.2017.1302754
- Description: Euplectes (Craig 1992). Body mass, high at the start of the breeding season and then declining, increases again during this post-nuptial moult (Craig 1978). An initial analysis of the timing of moult estimated the duration of wing-moult at 110 d on the basis of birds recaptured during moult (Craig and Manson 1979a). Later, these data were reanalysed using new mathematical methods (Craig et al. 2001), which yielded a shorter estimate of 89 d for completion of wing-moult. Moult data from different regions of southern Africa, with samples of> 50 birds, showed striking differences with estimates of the duration of wing-moult ranging from 62 to 114 d (Oschadleus and Underhill 2006; Craig et al. 2010). However, the earlier conclusion that the start of moult in Zimbabwe was significantly later than in KwaZulu-Natal (Craig and Manson 1979a) was not supported when a larger sample of birds from the summer rainfall region was examined (Craig et al. 2010). Nine captive male Red Bishops kept under constant conditions of 14 h light: 10 h dark continued normal cycles of wing-moult, and showed cycles of testis enlargement and regression, but retained either partial or full nuptial plumage over a two-year period (Craig 1985). This suggests that circannual rhythms may play some role in the timing of moult, but further experimental investigations are required to confirm this idea.
- Full Text:
- Authors: Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449401 , vital:74818 , https://www.tandfonline.com/doi/pdf/10.2989/00306525.2017.1302754
- Description: Euplectes (Craig 1992). Body mass, high at the start of the breeding season and then declining, increases again during this post-nuptial moult (Craig 1978). An initial analysis of the timing of moult estimated the duration of wing-moult at 110 d on the basis of birds recaptured during moult (Craig and Manson 1979a). Later, these data were reanalysed using new mathematical methods (Craig et al. 2001), which yielded a shorter estimate of 89 d for completion of wing-moult. Moult data from different regions of southern Africa, with samples of> 50 birds, showed striking differences with estimates of the duration of wing-moult ranging from 62 to 114 d (Oschadleus and Underhill 2006; Craig et al. 2010). However, the earlier conclusion that the start of moult in Zimbabwe was significantly later than in KwaZulu-Natal (Craig and Manson 1979a) was not supported when a larger sample of birds from the summer rainfall region was examined (Craig et al. 2010). Nine captive male Red Bishops kept under constant conditions of 14 h light: 10 h dark continued normal cycles of wing-moult, and showed cycles of testis enlargement and regression, but retained either partial or full nuptial plumage over a two-year period (Craig 1985). This suggests that circannual rhythms may play some role in the timing of moult, but further experimental investigations are required to confirm this idea.
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Seasonal population dynamics and energy consumption by waterbirds in a small temperate estuary
- Hean, Jeffrey W, Craig, Adrian J F K, Richoux, Nicole B
- Authors: Hean, Jeffrey W , Craig, Adrian J F K , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456305 , vital:75501 , xlink:href="https://doi.org/10.2989/00306525.2016.1230897"
- Description: Simple measures of population dynamics and energy consumption can provide baseline information on the role of consumers in food webs, particularly for cryptic or highly-mobile species of waterbirds. We provide estimates of the seasonal population dynamics and energy consumption of waterbirds along the Kowie Estuary, South Africa. Ten census counts were conducted every month along the estuary from June 2013 to May 2014. Energy consumption and fresh-matter intake were calculated based on body-mass equations. Piscivorous birds dominated the waterbird assemblage during summer (up to 289 individuals), whereas non-migratory shorebirds were dominant at other times of the year. The total wet mass of prey items ingested by waterbirds ranged from 2.8 kg ha−1 during winter to 8.5 kg ha−1 during summer. The total energy consumption of waterbirds ranged from 12 543 kJ ha−1 during June to 33 104 kJ ha−1 during December. Shannon–Wiener diversity calculations revealed that the Kowie Estuary had a greater diversity of waterbirds than several other South African estuaries, but less diversity than many large European estuaries. Studies that incorporate census counts and energy consumption measures, although rudimentary, may provide valuable information on resource use by waterbirds in estuaries and may benefit conservation management schemes.
- Full Text:
- Authors: Hean, Jeffrey W , Craig, Adrian J F K , Richoux, Nicole B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456305 , vital:75501 , xlink:href="https://doi.org/10.2989/00306525.2016.1230897"
- Description: Simple measures of population dynamics and energy consumption can provide baseline information on the role of consumers in food webs, particularly for cryptic or highly-mobile species of waterbirds. We provide estimates of the seasonal population dynamics and energy consumption of waterbirds along the Kowie Estuary, South Africa. Ten census counts were conducted every month along the estuary from June 2013 to May 2014. Energy consumption and fresh-matter intake were calculated based on body-mass equations. Piscivorous birds dominated the waterbird assemblage during summer (up to 289 individuals), whereas non-migratory shorebirds were dominant at other times of the year. The total wet mass of prey items ingested by waterbirds ranged from 2.8 kg ha−1 during winter to 8.5 kg ha−1 during summer. The total energy consumption of waterbirds ranged from 12 543 kJ ha−1 during June to 33 104 kJ ha−1 during December. Shannon–Wiener diversity calculations revealed that the Kowie Estuary had a greater diversity of waterbirds than several other South African estuaries, but less diversity than many large European estuaries. Studies that incorporate census counts and energy consumption measures, although rudimentary, may provide valuable information on resource use by waterbirds in estuaries and may benefit conservation management schemes.
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