Diet of a reintroduced marsupial 761


TABLE 3 Genera detected in.20% of adult brushtail possum scats and the mean proportion of those genera found in each scat using two primers (ndhJ and rbcL).


Genus


Eucalyptus Petalostylis Maireana


Zygophyllum Callitris Acacia Silene


Austrostipa Stackhousia Melaleuca Senna


Sonchus


Frequency of occurrence1 78.5


72.3 59.1 51.5 50.7 36.5 34.7 33.6 33.6 31.4 29.6 27.0


ndhJ 38.1


3.2 5.5 1.7 3.2 3.6 6.7 0.0 4.9 1.9 2.3 3.7


rbcL 8.8


32.2 2.5 0.9


18.4 2.8 5.4 2.0 0.0 5.2 2.2 0.0


Jacob’s Index ± SE2 −0.01 ± 0.2


1.00 ± 0.0 0.55 ± 0.1 0.94 ± 0.0


−1.00 ± 0.0 −0.09 ± 0.2


0.15 ± 0.2 0.21 ± 0.2 0.58 ± 0.2 1.00 ± 0.0


−0.39 ± 0.1 0.69 ± 0.1


P 0.15


,0.001 ,0.001 ,0.001 ,0.001 0.48 0.48 0.15 0.03


,0.001 0.03


,0.001


Preference Neutral


Preferred Preferred Preferred


Non-preferred Neutral Neutral Neutral


Preferred Preferred


Non-preferred Preferred


1% of scat samples containing the genus. 2Mean selectivity values for the study period and whether they significantly deviate fromzero (P); negative values indicate avoidance (non-preferred) relative to availability, positive values indicate preference.


acclimatization was not required for successful post-release reproduction under non-drought conditions. Post-release diet studies can be used to investigate the


diet of species reintroduced to areas where knowledge of their local diet may be limited, or when the feasibility of the translocation is unknown. The diets of the red-tailed phascogale Phascogale calura and mala Lagorchestes hirsu- tus were investigated as part of trial releases to determine the feasibility of reintroductions to other nearby areas (Stannard et al., 2010; Clayton et al., 2015), and the diet of translocated Gilbert’s potoroos was studied to determine whether sufficient fungi were present for population es- tablishment and reproduction (Bougher & Friend, 2009). Dietary studies can thus be used to inform acclimatiza- tion time, the feasibility of population establishment, the suitability of additional release locations and the species’ ecology. With some uncertainty as to the impacts of habitat degradation on possum survival in the National Park post- release, we found that food was sufficiently abundant and diverse to facilitate both survival and reproduction. Eucalypts had both the highest frequency of occurrence


in scats (78.5%) and the highest proportions within samples (making up an average of 23.5% of DNA extracted from scats) for scats collected in the National Park.However, pos- sums cannot consume an exclusively eucalypt diet: euca- lypts are high in fibre, relatively indigestible and contain terpenes (Foley & Hume, 1987; Boyle & McLean, 2004). A varied diet is therefore needed to meet their nutritional needs and energy demands (Marsh et al., 2006). The low number of preferred genera combined with the relatively high frequency of non-preferred genera in the brushtail possums’ diet suggests they feed opportunistically in small amounts, while consuming large amounts selectively. Drought conditions, not experienced during our study,


may exacerbate the need for possums to locate easily digest- ible, moist food plants. Foulkes (2001) found that the mois- ture content of mature foliagewas the only reliable predictor of possum occupancy in arid central Australia. Low avail- ability of traditionally preferred plants such as Santalum may explain low consumption (without noticeable conse- quence), but the importance of such nutritious and moist plants (Foulkes, 2001)may differ under drought conditions. In arid systems drought can negatively affect reintroduction success, as occurred for black-tailed prairie dog Cynomys ludovicianus populations in the Chihuahuan Desert (Facka et al., 2010), and red-necked ostriches Struthio camelus ca- melus in Saudi Arabia (Islam et al., 2008). Possums are well known for their plasticity and ability to adapt to different environments (Kerle, 1984; Kerle et al., 1991) and in this study we demonstrated persistence in an area where previ- ously identified preferred food plants are now uncommon. The diet of possums in the National Park should be moni- tored through the next drought period, to assess whether plants containing high moisture and nutrients are available in sufficient quantities to facilitate persistence. The majority of the genera present in the possums’ diet


were ground cover plants ,0.5 m in height but their com- bined frequency of occurrence in scats was low, suggesting they were only occasionally eaten, despite being the most diverse height class. Palatability was not accounted for, and many herbs and grasses were present but dry/senesced at various times during the study period. In contrast, few tall genera (.2.5 m height) were available compared to shrubs and annuals, but their frequency of occurrence within scats was high. This suggests that possums spend more time for- aging in the canopy than on the ground, a result supported by previous studies of possum foraging and movement, where diet is dominated by canopy species (Foulkes, 2001;


Oryx, 2021, 55(5), 755–764 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319000991


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164