Comparative diving behaviour ofBlue penguins at two NZ locations   Thomas Mattern1,2                    Lloyd S. Davis1   ...
Overview►   Introduction►   Study areas►   Foraging Ranges (revisited)►   Diving Behaviour►   Summary►   Acknowledgments
Introduction►   Foraging behaviour during early chick rearing     Birds have to return at regular intervals to feed small...
Study areas               Marlborough Sounds                        28. 08. – 29. 11. 2000                         Motuara...
Study areas               North Otago                    4. 12. 2000 – 21. 1. 2001                                  Oamaru...
Foraging ranges during chick rearing►   MOTUARA ISLAND     During ONE DAY TRIPS birds generally stayed within 9 km of the...
Foraging restrictions on One Day Trips      MOTUARA ISLAND              OAMARU
Measuring diving behaviour • Time-Depth Recorder (TDR) attached   to penguin‘s lower back • TDR records dive depth (via pr...
Diving behaviour - simplified►   Shallow foraging:     LOW DIVE FREQUENCY: 700-800 dives per day     SHALLOW (TRAVELLING...
Diving behaviour - simplified►   Deep foraging:     HIGH DIVE FREQUENCY: 1000-1200 dives per day     DEEP (FORAGING) DIV...
Diving behaviour as result of foraging restrictions                                     Motuara Island                 SHO...
Maximum dive depths OAMARU                                                                              (6 penguins, 10 fo...
Maximum dive depths MOTUARA ISLAND                                                                       (5 penguins, 8 fo...
Dive parameters (means)                                     OAMARU                MOTUARA IS.        p                    ...
Dive Duration                                             frequency the day-1                                             ...
Summary►   MOTUARA ISLAND:     Foraging range during chick rearing restricted by topography     Foraging efforts can onl...
Acknowledgements►   Big thanks to all Field Assistants Stef Klingel, Peter Deines,    Jana Kotzerka, Kirsten Martin and Ho...
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Foraging ranges and breeding success of Blue penguins Eudyptula minor at two different locations in New Zealand

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Breeding success and foraging ranges of blue penguins from Motuara Island/Marlborough Sounds and Oamaru/North Otago were examined during the breeding season 2000/2001. We examined 64 nests on Motuara Island and 87 nests at Oamaru. Breeding success parameters and chick growth were determined. Breeding success differed significantly between sites. Oamaru penguins raised 1.44 fledged chicks per pair compared with 0.71 on Motuara Island. Breeding failure on Motuara Island was generally related to chick starvation and nest desertions by adults, whereas at Oamaru, predation was the main mortality factor. Differences between the two sites were directly related to adult foraging strategies. We used VHF-telemetry to determine foraging routes and ranges of penguins equipped with streamlined transmitter packs. On Motuara Island we tracked penguins on 11 one-day-trips and five partial long-term trips (>2 days). At Oamaru penguins were tracked on 16 one-day trips and four longterm trips. Differences in foraging patterns between the populations were apparent. Motuara penguins rarely left the Queen Charlotte Sound on one-daytrips, stayed close to the Island (mean foraging range <6 km). Birds leaving the Sound on longterm trips generally stayed away for at least 2 days. Some adults undertook long-term trips during chick rearing. The main factors influencing the foraging behaviour of Motuara Island penguins seemed to be time dependent variations in prey availability and foraging restrictions by topographic features of Queen Charlotte Sound.

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Foraging ranges and breeding success of Blue penguins Eudyptula minor at two different locations in New Zealand

  1. 1. Comparative diving behaviour ofBlue penguins at two NZ locations Thomas Mattern1,2 Lloyd S. Davis1 Boris M. Culik2 Dave M. Houston3 1 Department of Zoology, University of Otago, Dunedin 2 Institute of Marine Sciences, University Kiel, Germany 3 Department of Conservation
  2. 2. Overview► Introduction► Study areas► Foraging Ranges (revisited)► Diving Behaviour► Summary► Acknowledgments
  3. 3. Introduction► Foraging behaviour during early chick rearing  Birds have to return at regular intervals to feed small chicks: Blue penguins generally return after 1 day at sea  Foraging behaviour depends primarily on foraging success  Poor foraging success can be compensated by: ► longer foraging trips (ie. greater travel distance) ► increased dive performance (ie. more dives per trip)  Environment dictates which compensation method is used
  4. 4. Study areas Marlborough Sounds 28. 08. – 29. 11. 2000 Motuara Island New Zealand
  5. 5. Study areas North Otago 4. 12. 2000 – 21. 1. 2001 Oamaru New Zealand
  6. 6. Foraging ranges during chick rearing► MOTUARA ISLAND  During ONE DAY TRIPS birds generally stayed within 9 km of the island  Birds leaving Queen Charlotte Sound performed LONG TERM TRIPS (>2d)► OAMARU  No LONG TERM TRIPS observed during chick rearing  Maximum distance from colony on ONE DAY TRIPS: 5 km to 30 km Foraging restricted by topography and maximum distance
  7. 7. Foraging restrictions on One Day Trips MOTUARA ISLAND OAMARU
  8. 8. Measuring diving behaviour • Time-Depth Recorder (TDR) attached to penguin‘s lower back • TDR records dive depth (via pressure transducer) at pre-defined time intervals • After recovery of device, recorded data is downloaded to computer • Raw data is converted to dive profiles for entire foraging trips • Special software analyzes every diving event for maximum dive depth, dive duration, dive type etc. depth duration
  9. 9. Diving behaviour - simplified► Shallow foraging:  LOW DIVE FREQUENCY: 700-800 dives per day  SHALLOW (TRAVELLING) DIVES: ca. 2.5 m to 5 m LONG-RANGE TRIPS (<30 km)?
  10. 10. Diving behaviour - simplified► Deep foraging:  HIGH DIVE FREQUENCY: 1000-1200 dives per day  DEEP (FORAGING) DIVES: ca. 5 to 35 m SHORT-RANGE TRIPS (<15 km)?
  11. 11. Diving behaviour as result of foraging restrictions Motuara Island SHORT-RANGE TRIP Oamaru SHORT-RANGE TRIP LONG-RANGE TRIP Foraging ranges on One Day Trips Dive profiles on One Day Trips
  12. 12. Maximum dive depths OAMARU (6 penguins, 10 foraging trips) 03:00 05:00 07:00 09:00 11:00 13:00 15:00 17:00 19:00 21:00 23:00 0 5 10 Maximum dive depth (m) 15 20 25 30 35 Total number of dives: 8066 40 mean maximum dive depth: 6.0 m (range: 2.5 – 33.5 m)
  13. 13. Maximum dive depths MOTUARA ISLAND (5 penguins, 8 foraging trips) 03:00 05:00 07:00 09:00 11:00 13:00 15:00 17:00 19:00 21:00 23:00 0 5 10 Maximum dive depth (m) 15 20 25 30 35 Total number of dives: 9323 40 mean maximum dive depth: 10.1 m (range: 2.5 – 35.5 m)
  14. 14. Dive parameters (means) OAMARU MOTUARA IS. p (n =6) (n = 5) (t-test) Diving activity (%)* 29.8 61.3 < 0.001 Dives per trip 808.9 1165.3 < 0.001 Dives per hour 47.8 75.3 < 0.001 Dive duration (s) 22.4 29.5 < 0.001 * diving activity = total dive duration / total trip duration * 100
  15. 15. Dive Duration frequency the day-1 hour of distribution dive depth-1 40 100 90 Motuara Island Oamaru 92 Oamaru 80 Motuara Island 35 84 70 76Mean dive duration (s) 30 Motuara Island 68 Oamaru 60 Mean dive duration (s) dive duration (s) 60 50 25 52 ADL 44 ADL 40 20 36 30 28 20 15 20 12 10 4 10 0 -1500 3 5 -1000 7 9 -500 11 130 15 500 17 19 1000 21 23 1500 2-6 6-10 10-14 14-18 18-22 22-26 26-30 > 30m Hour ofof dives number day Depth (m) • Greater dive efforts at Motuara Island (longer dives at any time of the day) • Better foraging performance at Oamaru (longer dives at greater depths) • High metabolic costs for 20% of the dives at Motuara Island, but only Island 9% of the dives at Oamaru (Aerobic Dive Limit reached or exceeded)
  16. 16. Summary► MOTUARA ISLAND:  Foraging range during chick rearing restricted by topography  Foraging efforts can only be extended vertically (ie. deeper dives)  High dive efforts (high dive activity)  Foraging success come at high metablic costs (ie. many deep dives)► OAMARU:  Penguins face no environmental foraging restriction  Foraging efforts can be extended vertically and/or horizontally (ie. greater distance travelled)  Low dive efforts  Foraging success comes at lower metabolic costs (ie. mainly shallow dives)
  17. 17. Acknowledgements► Big thanks to all Field Assistants Stef Klingel, Peter Deines, Jana Kotzerka, Kirsten Martin and Horst Mattern who endured storms and grumpy penguins. Kim Garret was our skillful skipper in the Marlborough Sounds.► Oamaru: Thank you to Denis Dove, Tony Hocken and Jennie Mills for looking after radiotagged stragglers► Marlborough Sounds: Thanks to Tony Tristram for his hospitality and help on Arapawa Island. Bill Cash and Pete Grady (DoC Picton) supported us during our stay on Motuara Island and Les & Zoe Battersby helped out with freshwater when we ran short.

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