Record of Predation by Sugar Glider on Breeding Eastern Rosellas 33Km NE of Melbourne in November 2016

Transcription

1 Record of Predation by Sugar Glider on Breeding Eastern Rosellas 33Km NE of Melbourne in November 2016 By Frank Pierce [ - jmandfp@bigpond.com.au ] 18/01/2016 SUMMARY Eastern Rosellas nested in a vertical hollow 2m from a house in the Bend of Islands 33km NE of Melbourne. 5 of the 6 chicks were killed by a Sugar Glider over 2 nights. The nest was then protected each night until the 6 th chick fledged. A second breeding attempt was abandoned during the incubation period. 1 st Breeding Attempt and Predation 20/10/16-7 eggs observed in nest 24/10/16 1st egg had hatched by 11.30am. More hatched during day. 27/10/16 observed that 6 eggs had hatched, attended by M (female parent) 3/11/16 chicks developed to stage where they could be fed and D (male parent) started attending as well as M 16/11/16 3 chicks found dead (1 substantially eaten) in am. These removed and Motion Camera set up 17/11/16 2 chicks found dead (1 substantially eaten). Photo of Sugar Glider at top of nest at 5.16am 17 to 26/11/16 wire cage placed over nest from dusk till dawn each night. 24/11/16 photos of Sugar Glider on cage over nest for 14+ minutes from 12.18am and 4+ minutes from 4.37am 26/11/16 surviving chick fledged 2 nd Breeding Attempt 7/12/16-3 eggs observed in nest 10/12/16-4 eggs observed in nest 14/12/16 - Plastic panel placed on trunk below nest to deter glider; birds abandoned nest 27/12/16 Birds returned, inspected nest but did not enter. (about end of incubation period for last egg) 29/12/16 & thereafter now clearly beyond the incubation period birds not seen again DETAILED RECORD Nest A vertical hollow, 150mm diameter x 500mm deep, ~3m above ground, at the top of a truncated dead Longleaf Box. Location 2m west of house on Round the Bend Conservation Cooperative, 199 Skyline Rd, Bend of Islands 3097 at ( ). The Bend of Islands is a recognised area of high conservation value and has special Residential Conservation zoning in the Shire of Nillumbik. Record of 1 st Breeding Attempt and Predation 20/10/16 7 eggs observed in nest at 8.20pm. (no adult sitting on nest at time of observation) Photo 1 24/10/16 1 st egg had hatched by 11.30am. More hatched during day. Photos 2 & 3 Photo pm Photo am Photo pm 25/10/16 to 3/11/16 6 eggs hatched, chicks developed each day attended by M (female parent) Photos 4 to 6 M typically left nest a couple of times a day for about 1 hour and flew off with D (male parent). 3/11/16 chicks developed to stage where they could be fed and D started attending as well as M

2 Photo am Photo am Photo am 4/11/16 to 15/11/16 chicks developed rapidly Photos 7 to 9 M & D would visit regularly to feed chicks. The adults were away from the nest for the majority of the day and it is not known when M stopped staying with the chicks at night. Photo am Photo am Photo am 16/11/16 1 live chick was found on the ground near to back door (8m from nest tree) at 7.20am. 2 live chicks and 3 dead chicks (1 substantially eaten) were in the nest. Photo 10. The dead chicks were removed from the nest (Photo 11) and the live chick was replaced. A Motion Camera was set up on the eaves of the house (2m from the nest) to record activities at the nest. (The camera had a time delay so not all movements were recorded. The adults were very quick at entering and leaving the nest and were not usually recorded, or sometimes the camera activated when they had gone) Photo am Photo am Photo am 17/11/16 1 live chick and 2 dead chicks (1 substantially eaten) were found in the nest at 6.55am Photo 13. The remote camera had recorded a photo of a Sugar Glider at the top of the nest at 5.16am Photo 12. The dead chicks were removed from the nest Photos 14 &15.The uneaten one was weighed (120mg) and measured (170mm head to claws).. A removable wire cage was made to fit over the nest. Photo 18 The surviving chick was seen to have climbed to the top of the nest at 2.15pm and again at 8.07pm Photos 14 to 17.

3 Photo am Photo am Photo am Photo pm Photo pm Photo pm 17 to 26/11/16 The wire cage was placed over the nest from dusk till dawn each night. The one surviving chick developed well with both M & D coming to feed it. It was seen at the top of the nest on 17/11 but not again from 18 to 26/11. 24/11/16 The Sugar Glider was photographed on the cage over the nest for 14+ minutes from 12.18am and 4+ minutes from 4.37am. So it is highly likely that this chick would also have been killed if the cage hadn t prevented access by the glider. Photo pm Photo am Photo am 25/11/16 Adult behaviour changed with them sitting at the top of the nest for extended periods and calling softly. (They seemed to be coaxing the chick to come to them) 26/11/16 The surviving chick fledged. (in the nest at 5.49am, gone at 8.32pm)

4 Photo am Photo am Photo pm 27/11/16 to 30/11/16 Easterns (Could be a different pair) and Crimsons both looking at nest from time to time. 1/12/16 to 6/12/16 Author away Record of 2 nd Breeding Attempt 7/12/16 - Home at 8.30pm. Put ladder to tree and bird flew out. Unable to ID bird. 3 eggs in nest 8/12/16 - Saw Eastern leave nest at 7.18am 3 eggs 9/12/ am Bird flew as soon as I started to climb ladder (as if it was already at the top of the nest) 3 eggs 10/12/ am Bird flew as soon as I started to climb ladder (perched to west) 4 eggs in nest. Male on tree west of house at 11.32am (eventually flew off to south) 11 to 13/12/16 4 eggs photo ed each morning. 14/12/16 ~ 2 pm Plastic panel (corrugated translucent roof sheeting) was placed on top 600mm of trunk below nest to deter glider access. - Photo 27. Bird flew off as nest was approached. (It took 20 minutes to install panel with lots of hammering). Did not see birds for rest of day. 15/12/16 Photo ed eggs in am. - Photo 28. Did not see birds all day 16/12/16 Photo ed eggs in am. - Photo 29. Eggs had been moved relative to each other. Did not see birds all day Photo 27 - Panel Photo am Photo am Photo am 17 to 21/12/16 Photo ed eggs in am. - Photo 30. Eggs moved relative to each other each day. Did not see birds any day 22 & 23/12/16 Author away 24/12/16 - Photo ed eggs in pm. Eggs had been moved relative to each other. Did not see birds 25/12/16 Author away 26/12/16 - Photo ed eggs in pm. Eggs had been moved relative to each other. Saw birds perched to west ~8.30pm. Flew to north 27/12/16 - Saw birds perched to west ~8.00am. Flew to north. - Birds back at 9.15am, 1 in tree to west & 1 on top of nest (not seen to enter nest) both flew to north - Photo ed eggs 12.50pm. Eggs had been moved relative to each other. 28/12/16 Author out till 5pm; Photo ed eggs 6pm. Eggs had been moved relative to each other. Did not see birds 29/12/16 & thereafter now clearly beyond the incubation period. Birds not seen again; Eggs still being moved (must be caused by something other than the birds cockroaches had been seen in nest sometimes)

5 DISCUSSION Predation by Sugar Glider Nest predation by Sugar Gliders for Swift Parrots in Tasmania was reported in ~2014. (Dejan Stojanovic et al 2014) Nest predation by Sugar Gliders has since been reported for Regent Honeyeaters in Victoria and Orange-bellied Parrots in Tasmania. Nest predation by Sugar Gliders is not mentioned in my 2 mammal reference books; Strahan 1983, or in Menkhorst & Knight Both references include invertebrates in sugar glider s diet but not birds or eggs. Observation of predation of nests has obviously been facilitated by the use of motion sensing infrared cameras which have become common over the last few years. Sugar Gliders are common in the Bend of Islands. There was a drop in numbers at the end of the Millennium Drought (2008+), however recent records (seen and heard) indicate that their numbers have recovered. The 2016/17 season is one of abundance with uncommonly high numbers of invertebrates and canopy growth, so there is no lack of normal food resources to cause the gliders to start to predate nests. It therefore seems probable that nest predation is a normal occurrence for Sugar Gliders. It also seems likely the gliders would predate the nests of smaller birds. Interference in the natural process My reaction was to protect the birds from further predation by the gliders, however my intervention may have been misguided o If the last chick had been taken, the birds may have commenced the 2 nd brood earlier and there may have been more food resources for them to complete the incubation o The birds may have been inexperienced and perhaps needed to learn to select a better protected nest site to avoid predation o My installation of the panel below the nest, probably caused the birds to abandon the 2 nd brood There are counter points to each of these possibilities, but it may be better to simply observe and record the natural process rather than to interfere. It would be a different scenario if the predator was introduced (as gliders are thought to be in Tasmania). CONCLUSION This report documents the predation of an Eastern Rosella nest by Sugar Gliders. The issues raised in the discussion have not been thoroughly researched. However, given the recent declines in woodland birds, further research into nest predation by Sugar Gliders and other predominantly nocturnal mammals could be appropriate.