Monarch colony (IMAGE) Frontiers Caption Abies religiosa (Sacred fir) covered by Monarch butterflies at Ejido La Mesa, 3340 m of elevation, core zone of MBBR. Seeds of Abies religiosa were collected at this site, to produce seedlings in a nursery that later were planted at Nevado de Toluca, at elevations of 3400 m, 3600 m, 3800 m and 4000 m. Credit Cuauhtémoc Sáenz-Romero, UMSNH Usage Restrictions Credit must be given to the creator. License CC BY Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.