City life is harsh and inhospitable for many animal species, particularly for non-volant mammals that face increased mortality risks in urban settings. Yet, studies on non-volant city mammals are limited and mostly restricted to temperate regions. Here, I evaluated the density and adaptability of the common marmoset (Callithrix jacchus), a species with a series of advantageous pre-adaptations that could facilitate city life, in highly built up urban environments of a tropical city Joao Pessoa (>800,000 people), in NE Brazil. I surveyed a total of 56 streets from seven randomly chosen districts within the city. I used multiple linear regression to determine the factors that could influence marmoset abundance. I found a total of 53 tree species of which half could be used as food resources. To reach food resources marmosets moved along and crossed streets using insulated power lines and phone cables. Marmoset density (66.9 ind/km²) was significantly low compared to populations inhabiting forest remnants. Nevertheless, along streets with high canopy cover, their density was similar to that reported for forest fragments. Canopy cover and trees providing food resources were key predictors of marmoset abundance. The presence of an exotic tree species (Terminalia catappa) that provides gum, showed to be key for groups persisting in extremely urbanized areas. Planting more of this species and increasing connectivity between forested areas are management strategies that might help long term persistence of marmosets in highly built up areas. Marmosets are common in Brazilian cities and could provide opportunities for contact with nature and increased well-being of human urban dwellers.

对于许多动物物种来说，城市生活是严酷和不适宜居住的，特别是对于在城市环境中面临更高死亡风险的非自由哺乳动物。然而，对非流浪城市哺乳动物的研究是有限的，而且主要限于温带地区。在这里，我评估了普通狨猴（Callithrix jacchus)，在巴西东北部热带城市若昂佩索阿 (> 800,000 人) 的高度建成的城市环境中，该物种具有一系列有利的预适应能力，可以促进城市生活。我调查了城市内随机选择的七个地区的总共 56 条街道。我使用多元线性回归来确定可能影响狨猴丰度的因素。我一共发现了53种树种，其中一半可以作为食物资源。为了获取食物资源，狨猴使用绝缘电线和电话线沿着街道移动并穿过街道。绒猴密度（66.9 ind/km ²) 与居住在森林残余物中的种群相比显着降低。然而，在树冠覆盖率高的街道上，它们的密度与报告的森林碎片密度相似。冠层覆盖和提供食物资源的树木是绒猴丰度的关键预测因子。提供树胶的外来树种（Terminalia catappa）的存在被证明是在极度城市化地区生存的关键。种植更多这种物种并增加森林地区之间的连通性是管理策略，可能有助于狨猴在高度建成的地区长期存在。狨猴在巴西城市很常见，可以提供与自然接触的机会，并提高人类城市居民的福祉。