Another callitrichid, Weddell’s saddleback tamarin (Saguinus fuscicollis weddelli) also occurs over much of Rondon's marmoset's range.[1] However, Rondon's marmoset is rare or absent from areas where Weddell's saddleback tamarin is common.[2] Weddell's saddleback tamarin is known to take over Rondon's marmoset's gum feeding sites.[2]