Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, P.O. Box 1066, Blindern, 0316, Oslo, Norway.
Department of Zoological Sciences, Addis Ababa University, P.O. Box: 1176, Addis Ababa, Ethiopia.
BMC Ecol. 2018 Feb 6;18(1):4. doi: 10.1186/s12898-018-0161-4.
Understanding the effects of habitat modification on the feeding strategies of threatened species is essential to designing effective conservation management plans. Bale monkeys (Chlorocebus djamdjamensis) are endemic to the rapidly shrinking montane forests of the southern Ethiopian Highlands. Most populations inhabit continuous bamboo forest subsisting largely on the young leaves and shoots of a single species of bamboo. Because of habitat disturbance in recent decades, however, there are now also several dozen small populations inhabiting isolated forest fragments where bamboo has been degraded. During 12-months, we assessed Bale monkey responses to habitat degradation by comparing habitat composition, phenological patterns, and feeding ecology in a largely undisturbed continuous forest (Continuous groups A and B) and in two fragments (Patchy and Hilltop groups).
We found that habitat quality and food availability were much lower in fragments than in continuous forest. In response to the relative scarcity of bamboo in fragments, Bale monkeys spent significantly less time feeding on the young leaves and shoots of bamboo and significantly more time feeding on non-bamboo young leaves, fruits, seeds, stems, petioles, and insects in fragments than in continuous forest. Groups in fragments also broadened their diets to incorporate many more plant species (Patchy: ≥ 47 and Hilltop: ≥ 35 species)-including several forbs, graminoids and cultivated crops-than groups in continuous forest (Continuous A: 12 and Continuous B: 8 species). Nevertheless, bamboo was still the top food species for Patchy group (30% of diet) as well as for both continuous forest groups (mean = 81%). However, in Hilltop group, for which bamboo was especially scarce, Bothriochloa radicans (Poaceae), a grass, was the top dietary species (15% of diet) and bamboo ranked 10th (2%).
We demonstrate that Bale monkeys are more dietarily flexible than previously thought and able to cope with some degradation of their primary bamboo forest habitat. However, crop raiding and other terrestrial foraging habits more common among fragment groups may place them at greater risk of hunting by humans. Thus, longitudinal monitoring is necessary to evaluate the long-term viability of Bale monkey populations in fragmented habitats.
了解栖息地改变对受威胁物种觅食策略的影响对于制定有效的保护管理计划至关重要。斑衣猕猴（Chlorocebus djamdjamensis）是埃塞俄比亚南部快速缩小的山地森林中的特有种。大多数种群栖息在以单一竹种的幼叶和嫩枝为主要食物的连续竹林中。然而，由于近几十年来的栖息地干扰，现在也有几十个小种群栖息在竹子退化的孤立森林片段中。在 12 个月的时间里，我们通过比较大面积未受干扰的连续森林（连续组 A 和 B）和两个片段（斑块和山顶组）的栖息地组成、物候模式和觅食生态，来评估斑衣猕猴对栖息地退化的反应。
我们发现，片段中的栖息地质量和食物供应明显低于连续森林。由于片段中竹子相对稀缺，斑衣猕猴在片段中花费在竹类幼叶和嫩枝上的觅食时间显著减少，而在非竹类幼叶、果实、种子、茎、叶柄和昆虫上的觅食时间显著增加，与连续森林相比。片段中的群体也扩大了它们的饮食范围，纳入了更多的植物物种（斑块：≥47 种和山顶：≥35 种），包括几种杂草、禾本科植物和栽培作物，而不是连续森林中的群体（连续 A：12 种和连续 B：8 种）。然而，竹子仍然是斑块组（占饮食的 30%）以及两个连续森林组（平均 81%）的顶级食物物种。然而，在山顶组中，竹子特别稀缺，斑茅（禾本科）是顶级饮食物种（占饮食的 15%），竹子排名第十（占 2%）。
我们证明，斑衣猕猴的饮食灵活性比以前认为的更高，能够应对其主要竹林栖息地的一些退化。然而，片段组中更常见的作物偷猎和其他陆地觅食习惯可能使它们面临更大的被人类捕猎的风险。因此，需要进行纵向监测，以评估斑衣猕猴在片段化栖息地中的长期生存能力。
