Howler monkey – Brazil

Howler monkey – Brazil

Reintroduction of the howler monkey (Alouatta clamitans) in Sao Paulo, Brazil, using telemetry.

Endemic and almost threatened of extinction in Sao Paulo state.

The use of telemetry has been of great importance in howlers monitoring because of difficulties imposed due to the closed vegetation and irregular topography of the areas.

Sao Paulo (23°32.0’S; 46°37.0’W), a crowded city of 11 million people, located in Brazil, has reduced its original vegetation during the past decades due to intense urbanization. This process leads to fragmentation of the Atlantic Forest and the loss of habitat for wild fauna. Such a huge pressure over biodiversity that still inhabits the green areas of the city damages wild animals that need medical care. For this reason, the Technical Division of Veterinarian Medicine and Management of Wildlife Fauna (Fauna Division) from the Green and Environment City Office was created in 1993. Fauna survey, veterinarian assistance, rehabilitation and release are some of its attributions.

The howler monkey Alouatta clamitans is one of hundreds of species received by Fauna Division. He is endemic and almost threatened of extinction in Sao Paulo state. His occurrence in the city is restricted to the north and south extremes and some fragments, isolated by irregular invasions. This conflicting situation provokes many accidents with howlers like electrocution, dog attack and orphan abandonment.

In order to return howlers to the nature, the Fauna Division developed the Experimental Program of Re-introduction that follows a clinical protocol for the city. In 1996, when this program started, howlers were released without radio-collars. The information after release came from people living in the released areas. To monitor howlers we ordered a RX-TLNX receiver, TXE-311 transmitters and a 3-element Yagi antenna. The equipment was purchased with resources of environmental compensation.

Three forms of transmitter adaptation were purchased from Telenax: ball chain collars, ball chain ankle band and backpack. It was decided to use collars only in females. For males we preferred to use the ankle band because the collar could interfere in their vocalization habits. The backpack didn’t fit in the howlers because of their anatomy. During the backpack test one howler removed the transmitter immediately after returning from sedation.

Until now five releases were conducted with the equipment in three forest fragments: Roda D’Água Ranch, Castanheiras Farm and New Hope Ranch. The three areas are located in the Area of Protection of Springs. In the first area we tracked a female during 9 months. In the second area we tracked one female during 8 months and we are still tracking another female since three months ago. In the third area we are now tracking one female since one month ago. It seems that the ankle band adaptation didn’t work for males as they lost them.

The Fauna Division team had the attention to previously test the transmitter in captivity at least for one week to observe if there was some change in animals behavior, or if they tried to take the transmitter out.  Information on how males lost their ankle band transmitter may indicate the need of a new form of adaptation for males (Note from Telenax: As of 2012 we have replaced metal ball chain for steel wire which has shown to be much more effective and potentially the solution for ankle attachment on male howler monkeys).
The use of telemetry has been of great importance in howlers monitoring because of difficulties imposed due to the closed vegetation and irregular topography of the areas. The topography seems to interfere more than vegetation; the range we are getting in this area is of about 1.5 Km from land. We always come near the place where the monkeys are, this enables us to find the tree where they are located. Howlers prefer to use the forest high strata. It was possible to visualize them most of the times.

We are really satisfied with the equipment because now we can know what happens with the howlers after releasing them, our goal since 1996. We can say that in about 90% of the cases we can get the signal in order to locate them. Without this equipment we couldn’t get important findings like survival, behavior patterns, feed behavior, home range, activities budget, etc. The entire team is happy with the telemetry efficiency.

Municipal Fund of Environment and Sustainability supports the howler monkey reintroduction project.


Text: Wagner Lacerda and Brígida Fries

Revision: Maria Eugênia Summa, Dafne Neves

Pictures: Marcos Kawall Vasconcelos

Acknowledgements: Tatiane Dubovicky



Dr. Vilma Geraldi


Fauna Division

City Office of the Green and Environment


Telenax whishes to thank Vilma Geraldi Ph. D., Brígida Fries, Wagner Lacerda and DEPAVE/PMSP for sharing their experiences

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