helen otley - Academia.edu (original) (raw)

Papers by helen otley

Research paper thumbnail of Aspects of the breeding biology of the Magellanic Penguin in the Falkland Islands

Waterbirds, Jan 1, 2004

The breeding biology of the Magellanic Penguin ( Spheniscus magellanicus ), including the timing ... more The breeding biology of the Magellanic Penguin ( Spheniscus magellanicus ), including the timing of laying, brooding and fledging, foraging trip lengths during incubation and brooding and diet in relation to breeding success, was investigated at Volunteer Beach in the north east of the Falkland Islands during the 2001/02 breeding season. Egg-laying dates were between 12 October and 1 November, with an overall hatching success of 65%. The length of foraging trips during incubation ranged from 2-15 days. Chicks were provisioned daily during the 23 day brood period, and then at a mean interval of two days during the unattended period, until fledging occurred in late January and early February. Successful pairs laid significantly earlier and undertook shorter foraging trips during incubation and brooding compared to unsuccessful pairs. The mean breeding success of 0.2 chicks/pair was low compared to the ten year mean at the study site and was possibly due to a lower abundance of squid, which is the preferred food for Magellanic penguin chicks in the Falkland Islands. The results obtained are discussed with regard to the breeding biology of the Magellanic Penguin on the mainland of South America. However, further research in subsequent seasons is required to determine whether the observed differences in breeding biology compared to elsewhere in the species range is typical behavior or the result of the changed prey availability.

Research paper thumbnail of Origin, age, sex and breeding status of wandering albatrosses (Diomedea exulans), northern (Macronectes halli) and southern giant petrels (Macronectes giganteus) …

Polar Biology, Jan 1, 2007

Research paper thumbnail of Platypus burrow temperatures at a subalpine Tasmanian lake

… -LINNEAN SOCIETY OF NEW …, Jan 1, 2004

When platypuses are in their burrows, microhabitat is of great importance for energy conservation... more When platypuses are in their burrows, microhabitat is of great importance for energy conservation, especially where air temperatures frequently fall below freezing in winter. In this study, we investigated burrow temperatures of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Nine individual platypuses were equipped with time-depth recorders with integrated temperature sensors measuring ambient temperature. Burrow temperatures were recorded in two minute intervals for a total of 61 resting periods (duration: 5.45 to 27.20 hours) and were averaged over the period of resting. Mean burrow temperatures were 17.5 and 14.2°C (SD=2.76 and 0.89, respectively, n=9) in summer and winter, respectively, and ranged between 12.2 and 22.8°C for individual resting periods. In winter, burrow temperatures were held fairly constant over the resting period while in summer larger variations were observed. Burrow temperature in winter was found to be up to 18°C higher than outside air temperature.

Research paper thumbnail of The use of a community-based survey to determine the distribution of the platypus Ornithorhynchus anatinus in the Huon River catchment, southern Tasmania

Australian Zoologist, Jan 1, 2001

A community-based survey was conducted t o establish the current distribution of the platypus Orn... more A community-based survey was conducted t o establish the current distribution of the platypus Ornithorhynchus anotinus in the Huon River catchment, southern Tasmania. The species was found t o be common and sighted in waterbodies throughout the Huon River catchment. Fewer platypuses were sighted in the eastern part of the catchment, where rainfall is lower and mudstone is the dominant geology. The absence of platypus sightings from some rivers needs further investigation as it may reflect geology, stream ecology or land use practices. Smaller waterbodies such as farm dams and creeks appeared t o provide important habitat. A number of platypuses were also observed in estuarine areas where salinity levels were high. The survey also indicated that the platypus is an effective icon species for raising community awareness of the issues surrounding catchment management and river protection.

Research paper thumbnail of Nature-based tourism: experiences at the Volunteer Point penguin colony in the Falkland Islands

Marine Ornithology, Jan 1, 2005

Research paper thumbnail of Trends in seabird and Patagonian toothfish Dissostichus eleginoides longliner interactions in Falkland Island waters, 2002/03 and 2003/04

Marine Ornithology, Jan 1, 2007

OTLEY, H.M., REID, T.A. & POMPERT, J. 2007. Trends in seabird and Patagonian Toothfish Dissostich... more OTLEY, H.M., REID, T.A. & POMPERT, J. 2007. Trends in seabird and Patagonian Toothfish Dissostichus eleginoides longliner interactions in Falkland Island waters, 2002/03 and 2003/04. Marine Ornithology 35: 47-55.

Research paper thumbnail of Marine debris surveys at Volunteer Beach, Falkland Islands, during the summer of 2001/02

Marine pollution bulletin, Jan 1, 2003

Research paper thumbnail of Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus

… and Physiology-Part A: Molecular & …, Jan 1, 2003

We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural a... more We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural aerobic dive limit (ADL) of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Individual platypuses were equipped with combined data logger-transmitter packages measuring dive depth. Mean dive duration was 31.3 s with 72% of all dives lasting between 18 and 40 s. Mean surface duration was 10.1 s. Mean dive depth was 1.28 m with a maximum of 8.77 m. Platypuses performed up to 1600 dives per foraging trip with a mean of 75 dives per hour. ADL was estimated by consideration of post-dive surface intervals vs. dive durations. Only 15% of all dives were found to exceed the estimated ADL of 40 s, indicating mainly aerobic diving in the species. Foraging platypuses followed a model of optimised recovery time, the optimal breathing theory. Total bottom duration or total foraging duration per day is proposed as a useful indicator of foraging efficiency and hence habitat quality in the species. ᮊ

Research paper thumbnail of Activity patterns, movements and burrows of platypuses (Ornithorhynchus anatinus) in a sub-alpine Tasmanian lake

Australian Journal of Zoology, Jan 1, 2000

... Helen M. Otley, Sarah A. Munks and Mark A. Hindell ... other small semi-aquatic mammals such ... more ... Helen M. Otley, Sarah A. Munks and Mark A. Hindell ... other small semi-aquatic mammals such as desmans (Galemys pyrenaicus), muskrats (Ondatra zibethicus) and beavers (Castor canadensis) feed in short bouts during extremely cold conditions (MacArthur 1979; Lancia et ...

Research paper thumbnail of Aspects of the breeding biology of the southern rockhopper penguin Eudyptes c. chrysocome and new consideration on the intrinsic capacity of the A-egg

Polar Biology, Jan 1, 2008

The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseley... more The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseleyi and the southern E. chrysocome rockhopper penguin. It is therefore crucial to have a comprehensive understanding of the biology of each species in order to develop appropriate conservation measures. We investigated the breeding biology of the southern rockhopper on New Island, in the western part of the Falklands Islands, by following the breeding attempt of 160 pairs during the 2006/2007 season and examining the eVect of lay time and colony habitat on breeding success. SpeciWcally, we compared survival and growth parameters between A-and B-eggs and chicks from non-manipulated and artiWcially manipulated nests to investigate why southern rockhopper penguins in the Falkland Islands are more able to Xedge an A-egg (Wrst laid) than conspeciWcs elsewhere. Breeding was highly synchronous, with no signiWcant diVerence in the breeding success between early and late breeders or between pairs breeding in diVerent habitats. We demonstrate for the Wrst time that the A-egg produced by the southern rockhopper penguin has, when alone, the same theoretical intrinsic potential to lead to a Xedged chick as the B-egg. In contrast, the hatching success and survival of the B-chick was similar when alone or in a two-egg clutch.

Research paper thumbnail of Aspects of the breeding biology of the Magellanic Penguin in the Falkland Islands

Waterbirds, Jan 1, 2004

The breeding biology of the Magellanic Penguin ( Spheniscus magellanicus ), including the timing ... more The breeding biology of the Magellanic Penguin ( Spheniscus magellanicus ), including the timing of laying, brooding and fledging, foraging trip lengths during incubation and brooding and diet in relation to breeding success, was investigated at Volunteer Beach in the north east of the Falkland Islands during the 2001/02 breeding season. Egg-laying dates were between 12 October and 1 November, with an overall hatching success of 65%. The length of foraging trips during incubation ranged from 2-15 days. Chicks were provisioned daily during the 23 day brood period, and then at a mean interval of two days during the unattended period, until fledging occurred in late January and early February. Successful pairs laid significantly earlier and undertook shorter foraging trips during incubation and brooding compared to unsuccessful pairs. The mean breeding success of 0.2 chicks/pair was low compared to the ten year mean at the study site and was possibly due to a lower abundance of squid, which is the preferred food for Magellanic penguin chicks in the Falkland Islands. The results obtained are discussed with regard to the breeding biology of the Magellanic Penguin on the mainland of South America. However, further research in subsequent seasons is required to determine whether the observed differences in breeding biology compared to elsewhere in the species range is typical behavior or the result of the changed prey availability.

Research paper thumbnail of Origin, age, sex and breeding status of wandering albatrosses (Diomedea exulans), northern (Macronectes halli) and southern giant petrels (Macronectes giganteus) …

Polar Biology, Jan 1, 2007

Research paper thumbnail of Platypus burrow temperatures at a subalpine Tasmanian lake

… -LINNEAN SOCIETY OF NEW …, Jan 1, 2004

When platypuses are in their burrows, microhabitat is of great importance for energy conservation... more When platypuses are in their burrows, microhabitat is of great importance for energy conservation, especially where air temperatures frequently fall below freezing in winter. In this study, we investigated burrow temperatures of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Nine individual platypuses were equipped with time-depth recorders with integrated temperature sensors measuring ambient temperature. Burrow temperatures were recorded in two minute intervals for a total of 61 resting periods (duration: 5.45 to 27.20 hours) and were averaged over the period of resting. Mean burrow temperatures were 17.5 and 14.2°C (SD=2.76 and 0.89, respectively, n=9) in summer and winter, respectively, and ranged between 12.2 and 22.8°C for individual resting periods. In winter, burrow temperatures were held fairly constant over the resting period while in summer larger variations were observed. Burrow temperature in winter was found to be up to 18°C higher than outside air temperature.

Research paper thumbnail of The use of a community-based survey to determine the distribution of the platypus Ornithorhynchus anatinus in the Huon River catchment, southern Tasmania

Australian Zoologist, Jan 1, 2001

A community-based survey was conducted t o establish the current distribution of the platypus Orn... more A community-based survey was conducted t o establish the current distribution of the platypus Ornithorhynchus anotinus in the Huon River catchment, southern Tasmania. The species was found t o be common and sighted in waterbodies throughout the Huon River catchment. Fewer platypuses were sighted in the eastern part of the catchment, where rainfall is lower and mudstone is the dominant geology. The absence of platypus sightings from some rivers needs further investigation as it may reflect geology, stream ecology or land use practices. Smaller waterbodies such as farm dams and creeks appeared t o provide important habitat. A number of platypuses were also observed in estuarine areas where salinity levels were high. The survey also indicated that the platypus is an effective icon species for raising community awareness of the issues surrounding catchment management and river protection.

Research paper thumbnail of Nature-based tourism: experiences at the Volunteer Point penguin colony in the Falkland Islands

Marine Ornithology, Jan 1, 2005

Research paper thumbnail of Trends in seabird and Patagonian toothfish Dissostichus eleginoides longliner interactions in Falkland Island waters, 2002/03 and 2003/04

Marine Ornithology, Jan 1, 2007

OTLEY, H.M., REID, T.A. & POMPERT, J. 2007. Trends in seabird and Patagonian Toothfish Dissostich... more OTLEY, H.M., REID, T.A. & POMPERT, J. 2007. Trends in seabird and Patagonian Toothfish Dissostichus eleginoides longliner interactions in Falkland Island waters, 2002/03 and 2003/04. Marine Ornithology 35: 47-55.

Research paper thumbnail of Marine debris surveys at Volunteer Beach, Falkland Islands, during the summer of 2001/02

Marine pollution bulletin, Jan 1, 2003

Research paper thumbnail of Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus

… and Physiology-Part A: Molecular & …, Jan 1, 2003

We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural a... more We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural aerobic dive limit (ADL) of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Individual platypuses were equipped with combined data logger-transmitter packages measuring dive depth. Mean dive duration was 31.3 s with 72% of all dives lasting between 18 and 40 s. Mean surface duration was 10.1 s. Mean dive depth was 1.28 m with a maximum of 8.77 m. Platypuses performed up to 1600 dives per foraging trip with a mean of 75 dives per hour. ADL was estimated by consideration of post-dive surface intervals vs. dive durations. Only 15% of all dives were found to exceed the estimated ADL of 40 s, indicating mainly aerobic diving in the species. Foraging platypuses followed a model of optimised recovery time, the optimal breathing theory. Total bottom duration or total foraging duration per day is proposed as a useful indicator of foraging efficiency and hence habitat quality in the species. ᮊ

Research paper thumbnail of Activity patterns, movements and burrows of platypuses (Ornithorhynchus anatinus) in a sub-alpine Tasmanian lake

Australian Journal of Zoology, Jan 1, 2000

... Helen M. Otley, Sarah A. Munks and Mark A. Hindell ... other small semi-aquatic mammals such ... more ... Helen M. Otley, Sarah A. Munks and Mark A. Hindell ... other small semi-aquatic mammals such as desmans (Galemys pyrenaicus), muskrats (Ondatra zibethicus) and beavers (Castor canadensis) feed in short bouts during extremely cold conditions (MacArthur 1979; Lancia et ...

Research paper thumbnail of Aspects of the breeding biology of the southern rockhopper penguin Eudyptes c. chrysocome and new consideration on the intrinsic capacity of the A-egg

Polar Biology, Jan 1, 2008

The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseley... more The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseleyi and the southern E. chrysocome rockhopper penguin. It is therefore crucial to have a comprehensive understanding of the biology of each species in order to develop appropriate conservation measures. We investigated the breeding biology of the southern rockhopper on New Island, in the western part of the Falklands Islands, by following the breeding attempt of 160 pairs during the 2006/2007 season and examining the eVect of lay time and colony habitat on breeding success. SpeciWcally, we compared survival and growth parameters between A-and B-eggs and chicks from non-manipulated and artiWcially manipulated nests to investigate why southern rockhopper penguins in the Falkland Islands are more able to Xedge an A-egg (Wrst laid) than conspeciWcs elsewhere. Breeding was highly synchronous, with no signiWcant diVerence in the breeding success between early and late breeders or between pairs breeding in diVerent habitats. We demonstrate for the Wrst time that the A-egg produced by the southern rockhopper penguin has, when alone, the same theoretical intrinsic potential to lead to a Xedged chick as the B-egg. In contrast, the hatching success and survival of the B-chick was similar when alone or in a two-egg clutch.