BDBSA Project Metadata Detail

Survey/Project Number: 1141          Total No. of Sites: 23
Survey/Project Name: Yellow-tail Black Cockatoo - MLR - Estimating Sex Ratios
Abstract: This project aims to estimate sex ratios of Yellow-tailed Black Cockatoo [YTBC] (Calyptorhyncus funereus), a large, endemic cockatoo found across the temperate regions of south-eastern Australia. BACKGROUND: YTBC inhabit sclerophyll forest, woodland and heath, feeding predominantly on seeds (especially of proteaceous species), but also invertebrate larvae extracted from wood and occasionally flowers and nectar (Higgins 1999, Cameron 2007). They are also frequently seen in introduced Pinus plantation forests. In South Australia they are listed as a vulnerable species at both the state level and in the survey area of the Adelaide and Mount Lofty Ranges conservation assessment region (DEWNR 2013). This is due to the small size of the two population (<10,000 individuals) and its relative isolation, though birds are thought to occasionally move between populations on Kangaroo Island and the South-east (Dawson 1994, Carpenter et al. 2012). During the non-breeding season, flocks of YTBC appear to have a daily routine that occurs over a defined area; many flocks are known to roost in native vegetation then head to Pinus plantations to feed during the morning, moving methodically between stands of trees bearing cones. The middle of the day sees a drop in activity, which increases again in the afternoon. At dusk the flocks head to their roosting areas, usually only a few kilometres from their feeding grounds (Forshaw & Cooper 2016). Most of the local population are thought to comprise these aggregations during the non-breeding season, so provide an opportunity for relatively comprehensive regional population census; surveys of this scope would be impractical during the breeding season as paired birds are spread over the MLR and are much more covert in their behaviour. METHODOLOGY: Census counts were undertaken in 2011 and 2012 using multiple observers across the MLR. These surveys estimated that the population in the MLR is between 1000-2000 birds (Carpenter et al. 2012); no YTBC census has been undertaken in the region since. During these censuses, a subset of the flocks counted were also sexed; in 2011, 60% of the 255 birds sexed were adult males, and in 2012, 47% of the 288 birds sexed were adult males (Carpenter et al. 2012). Given that the non-male counts include juveniles and immature birds to 3-4 years in age as well as adult females, a near 50% split may still represent a male-skewed sex ratio in this adult YTBC population, and a 60% count of adult males certainly suggests this. Skewed sex ratios have implications for conservation as they reduce the effective reproductive capacity, and therefore population viability; a particular concern in small, isolated populations (Donald 2007, Koenig 2016). Carpenter et al. (2012) noted that if there was a 60:40 male-skewed sex ratio in the ~2000 MLR YTBCs, and between 25-50% of non-male birds being juveniles, immatures or adult females that are unable to breed, the estimation of breeding capacity would drop from 500-750 pairs (at a 50:50 sex ratio) to 400-600 pairs, an effective population size of 800-1200 breeding birds, a relatively small proportion of a population of only 2000 birds. REFERENCES: Estimating sex ratios in flocks of Yellow-tailed Black Cockatoos (Calyptorhyncus funereus) during the non-breeding season in the Mount Lofty Ranges, South Australia, Thomas Hunt.
 
Start Date: 04/08/2016      End Date: 31/08/2020
Survey Type: Fauna only
   
Study Area Description: The study were undertaken in the Second Valley Forest Reserve and Mount Hayfield across the localities of Delamere, Second Valley, Parawa and Hay Flat. The reserve comprises 2800 hectares of Pinus plantation forest and small areas of remnant native bushland, especially in gullies and riparian areas.
Objectives
         Vegetation: *** No vegetation survey objectives recorded
         Fauna: Concerns of a male-skewed adult sex ratios in the YTBC population in the MLR were the impetus behind this study. The aim was to assess the population viability of YTBCs in the MLR by determining if the sex ratios of aggregated flocks during the non-breeding season were skewed. The objectives were to (1) locate and count flocks of YTBCs to provide an estimate of population size in the region (2) record the number of adult males and females/young observed in flocks, (3) assess recruitment by recording the number of young observed or heard in flocks, (4) record the location of the flocks and describe flock behaviour.
Methodology
         Vegetation: *** No vegetation methodology recorded
         Fauna: The timing of these surveys was aimed to coincide with the autumn and winter non-breeding aggregations of YTBCs in the MLR, as larger flocks are easier to count and sex.Surveys took place over 6 days between the 4th and 10th of August 2016. Visits commenced any time from dawn (around 7:30 hrs) and ended before dusk (around 17:30 hrs); survey stints ranged from four to eight hours. Surveying on the 9th of August was cut short due to heavy rainfall. Total survey time came to 36 hours.Birds were located by driving and walking along tracks in the reserve and roads in the surrounding area, looking and listening for YTBCs. When located, flocks were pursued to obtain views that would allow the highest accuracy flock counts and enable the greatest proportion of the flock to be sexed.Locations of initial observations were recorded with a Garmin GPS 60, using eastings and northing coordinates in UTM 54H. If seen at a distance from the observer, coordinates were adjusted accordingly (e.g. if birds seen 200 m east from point "easting A, northing B", coordinates were adjusted to "easting A+200, northing B"); if birds were heard only, distance and direction from observer were estimated and the coordinates adjusted in the same manner. Once located, flocks were followed until a satisfactory proportion were counted and/or sexed, or they flew too great a distance to follow on foot (e.g. over a valley and out of sight). Given juveniles and immatures are similar to adult females, only 3-4+ year males can could be definitively sexed, and non-male birds could only be categorised collectively as females, juveniles and immatures. Flocks were counted and some sexed using Swarovski EL 10 x 42 binoculars; this data was augmented where possible (especially for large flocks) using photographs taken with a wide angle or a telephoto lens. Sexes were tallied separately; when individuals could not be sexed due to position of the birds, objects obscuring them or poor lighting conditions, they were tallied as `unknown sex'.

Data Distribution Rules: Public Dataset
Project Basis: Fauna : Fauna species/population Study (ie trapping records over time period for species study). NOTE:NON Std Svy methodology may have been used.
Information Authority: Department for Environment and Heritage (BDBSA:Adelaide)
University of Adelaide
Adelaide and Mount Lofty Ranges Natural Resources Management (NRM) Region