568 P. Adamski and A. M. C´miel
population is unlikely to have maintained itself above the habitat’s carrying capacity for six consecutive years (1998– 2003). Otherwise, given the constant, high carrying capacity of the habitat, it is difficult to explain the population’s
TABLE 2 The fit of the six modelled scenarios (see text for details) to the field data.
Modelled scenario1 WO K1
WO+ shift WO K2 CI K1
CI + shift CI K2
R2
0.6683 0.8520 0.7098 0.5376 0.4323 0.4512
95% CI
0.400–0.831 0.707–0.928 0.464–0.864 0.214–0.755 0.079–0.689 0.102–0.701
1WO K1, not including captive-reared individuals, constant carrying capacity K1 = 1,294; WO+ shift, not including captive-reared individuals, carrying capacity reduced from K1 = 1,294 to K2 = 716;WO K2, not including captive-reared individuals, constant carrying capacity K2 = 716; CI K1, including captive-reared individuals, constant carrying capacity K1 = 1,294; including captive-reared individuals, carrying capacity reduced from K1 = 1,294 to K2 = 716;CIK2, including captive-reared individuals,
constant carrying capacity K2 = 716. 2Correlation coefficient; all significant at P,0.0001.
stabilization at the lower level of abundance after the col- lapse in 2004. It is, however, surprising that the scenarios not involving
supplementation with captive-reared individuals were gen- erally a better fit to the field data than those including such supplementation (Table 2, Figs 3–4). This difference is par- ticularly conspicuous with regard to 1992–1997. The model involving captive-reared individuals indicates that the car- rying capacity should have been reached within 2 years, but it took twice as long; the recovery schedule could have been responsible for this. The estimated pre-restoration car- rying capacity was based only on host plant abundance, whereas one reason for the Apollo population’s critical sta- tus was the loss of dry grasslands associated with limestone scree (Witkowski et al., 1996, 1997; Adamski & Witkowski, 2002, 2007). In the first phase of the recovery project, captive-reared individuals were introduced in parallel with habitat restoration. The planned habitat conditions at all the sites covered by the project had been achieved by 1997 (Witkowski et al., 1997; Adamski & Witkowski, 1999a; Adamski, 2016), the year when the population reached a level similar to the carrying capacity estimated on the basis of host plant abundance. It is possible either that
FIG. 4 Residual analysis of the actual population abundance and the values expected according to the six modelled scenarios, from 1990 to 2019. See text for details of the scenarios.
Oryx, 2022, 56(4), 564–571 © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605321000296
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