While Jon developed the overall Treetop Trails design concept, his old firm CLRdesign developed design details as well as this plan showing the first stage connecting the existing primate indoor dioramas in the heritage Rare Mammal House to the outdoor loop circling the existing Impala Plasa near the Philadelphia Zoos’ main entry. Note the two gateways protecting visitors on the main walkway from possible urine from the primates crossing above, and also the three off-trail play nodes where primate can spend time with enrichment features and feeders. Two important features of this concept are 1. It integrates well with a protected heritage building and 2. The use of existing park land to greatly expand opportunaties for the primates. Philly Zoo developed the slogan “As you move through the zoo, the zoo moves around you!”

The left photo shows the loop trail passing near picnic tables with one of the play nodes built around a large existing sysamore tree. The photo on the right shows a mangabey’s view from inside the trail (photo: Philadelphia Zoo).

Treetop Trails was the first of the Philly Zoo360 animal rotation trails and opened in 2011. It included 152m (500lf) of one meter diameter flexible mesh circling the public area and 76m (250’) of square cross section ridged mesh over the old Rare Mammal building connecting to eleven existing indoor primate exhibits. The total length is 228m (750’). Initially ten species of primate alternately used the trail loop: Red-capped mangabey, Blue-eyed black lemur, Mongoose lemur, Douc langur, Geoffroy’s marmoset, Goeldi’s monkey, Golden lion tamarin, Pied tamarin, White-faced saki, and pygmy marmoset. Coquevel’s safaka and black and white roughed lemurs were later included.

Dr. Marieka Gartner studied the primate’s anticipatory behaviour and choice when offered access to the Treetop Trails. She found that lemurs chose to use the trail 80% of the time. Occausions they chose to stay home may have been weather related. Unfortunately, no data was published on how the various primates used the trails or the length of time and frequency of their use.

Treetop Trails was later extended to a total length of 500m (1640’), creating a round trip length of one kilimeter, a long distance for a pygmy marmoset!

In 2013 Jon was invited to Zoo Guadalajara to give a lecture at their Future of Zoos Conference. During his tour of the zoo with Primate Curator Dr. Luis Soto Rendón Jon suggested they develop elevated trails (Sendario Aerios) for some of their primates and later Dr. Rendón sent Jon photos of the completed work which Jon visited in 2018. The completed trail loop is 600m (2000’) long, was constructed by zoo staff and is very popular with zoo visitors.

Note that unlike Treetop Trails at Philadelphia Zoo, Sendario Aerios crosses and even follows public pathways without concern for visitors standing below the primates. They also simplified the gateways between trail segments.These long trails  provides a variety of exercise and exploration opportunities for several primate species. During Jon’s second visit, black and white roughed lemurs alternated with a large troop of squiral monkeys. Each species enjoyed a half of the day in the trail system before returning to their usual enclosures.