Goldingay Ross L, McHugh Darren, Parkyn Jonathan L
Faculty of Science Southern Cross University Lismore New South Wales Australia.
Ecol Evol. 2022 May 24;12(5):e8935. doi: 10.1002/ece3.8935. eCollection 2022 May.
Multiyear investigations of population dynamics are fundamental to threatened species conservation. We used multiseason occupancy based on spotlight surveys to investigate dynamic occupancy of the koala and the greater glider over an 8-year period that encompassed a severe drought in year 6. We combined our occupancy estimates with literature estimates of density to estimate the population sizes of these species within the focal conservation reserve. Both species showed substantial yearly variation in the probability of detection (koala: 0.13-0.24; greater glider: 0.12-0.36). Detection of the koala did not follow any obvious pattern. Low detection of the greater glider coincided with the drought and two subsequent years. We suggest the low detection reflected a decline in abundance. The probability of occupancy of the koala was estimated to be 0.88 (95% CI: 0.75-1.0) in year 8. Autonomous recording units were also used in year 8, enabling an independent occupancy estimate of 0.80 (0.64-0.90). We found no evidence of a drought-induced decline in the koala. Habitat variables had a weak influence on koala occupancy probabilities. The probability of occupancy of the greater glider changed little over time, from 0.52 (95% CI: 0.24-0.81) to 0.63 (0.42-0.85) in year 8. Modeling suggested that the probability of colonization was positively influenced by the percentage cover of rainforest. Increased cover of these nonbrowse trees may reflect thermal buffering, site productivity, or soil moisture. We estimate that our study reserve is likely to contain >900 adult koalas and >2400 adult greater gliders. These are among some of the first reserve-wide estimates for these species. Our study reserve can play an important role in the conservation of both species.
对种群动态进行多年调查是濒危物种保护的基础。我们基于聚光灯调查采用多季节占有率方法，在长达8年的时间里调查了考拉和大滑翔机的动态占有率，其中第6年遭遇了严重干旱。我们将占有率估计值与文献中的密度估计值相结合，以估算这些物种在重点保护区域内的种群数量。两种物种的检测概率都呈现出显著的年度变化（考拉：0.13 - 0.24；大滑翔机：0.12 - 0.36）。考拉的检测没有呈现出任何明显模式。大滑翔机的低检测率与干旱及随后两年相吻合。我们认为低检测率反映了其数量的下降。在第8年，考拉的占有率估计值为0.88（95%置信区间：0.75 - 1.0）。第8年还使用了自动记录装置，得出的独立占有率估计值为0.80（0.64 - 0.90）。我们没有发现干旱导致考拉数量下降的证据。栖息地变量对考拉占有率概率的影响较弱。大滑翔机的占有率概率随时间变化不大，从第1年的0.52（95%置信区间：0.24 - 0.81）变为第8年的0.63（0.42 - 0.85）。模型表明，雨林覆盖百分比对定殖概率有正向影响。这些非食用树木覆盖的增加可能反映了热缓冲、场地生产力或土壤湿度。我们估计我们的研究区域可能包含超过900只成年考拉和超过2400只成年大滑翔机。这些是对这些物种在保护区范围内的首批估计数据之一。我们的研究区域在这两个物种的保护中可以发挥重要作用。
