Creating a comprehensive inventory of the species present sounds relatively easy, but the inaccessibility of much of the land and the retiring nature of many of the species makes it difficult to survey even the easiest groups, such as birds. After ten years of regular visits from experienced birdwatchers new species for the reserve are still being found, and there could be as many as another 30 species to be discovered at higher altitudes. Whilst many visitors can contribute important bird and mammal records, the work of finding and identifying bats, amphibians, reptiles, insects and plants is mainly left to the professionals and university students that are now regular visitors to REGUA.

REGUA has always been keen to develop close working relationships with Brazilian research and educational institutions and organisations for mutual benefit. REGUA can provide a safe environment with high quality habitat in which to conduct the studies, plus accommodation when required and practical support from its staff. In return, REGUA gets the results of the work which improves our understanding of the environment and biodiversity that we are protecting, and provides input to our habitat and species management plans.

After the early bird surveys, the first scientific survey was carried out in 2001 when the Rio de Janeiro Natural History Museum visited to carry out an inventory of arachnidae and ichthyofauna. Whilst no new species to science were discovered, they did confirm that REGUA contained high quality forest and identified the reserve as a suitable location for further research.

In 2002, REGUA signed a cooperation agreement with the University Maria Theresa of Niteroi (FAMATh) and the University of Serra dos Orgões in Teresopolis (FESO). During their two year research programme REGUA received over 20 students completing their degrees in Biology and Veterinary science (wild animals department) who helped compile an animal species inventory using basic and inexpensive field methods such as pitfall and camera traps, mist nets and basic observation walks. This was followed in 2002-03 by a team of two researchers and two students from FESO who collected additional data on a monthly basis. The final results were published in two theses with lists of species and their geographical distribution.

In 2002 the 46,000 hectare Três Picos Park was created and REGUA immediately signed a co-operation agreement with the State Forestry Institute (IEF) permitting the continuation of all research in the reserve. In 2003 Eduardo Rubião joined the staff at REGUA to coordinate the research, and he was instrumental in establishing the trail network and training the rangers in basic monitoring work. Also in 2003 Rio de Janeiro State University together with the BIOMAS Institute undertook the first survey of the amphibians and reptiles at REGUA.

In 2003-04 REGUA invited the Brazilian ornithologist Dr Fabio Olmos to conduct a survey of all the bird species present at REGUA. This study confirmed that REGUA met the Birdlife Brazil criteria to be listed as an Important Bird Area (IBA) with an extensive list of high quality and endangered birds. This survey also helped promote REGUA as an excellent potential site for the reintroduction of the Red-billed Curassow Crax blumbachi in Rio State. In 2005 this reintroduction project received its approval from IBAMA, and the first 20 birds bred at the Crax Institute of Belo Horizonte were released at REGUA in August 2006.

All the birds released were equipped with radio transmitters to be monitored by Christine Steiner of the University of São Paulo as part of a PhD study. In 2007 another 20 Red-billed Curassows and a group of 20 Black-fronted Piping-Guans Aburria jacutinga were released. Although further releases were planned, the absence of suitable birds for release prevented the successful completion of this work, although a great amount of information was gained which will undoubtedly benefit other release programmes.

The creation in 2005 of the extensive wetlands at REGUA in the old São José Farm provided Professor Tim Moulton of the UERJ with an excellent opportunity to monitor the development and changes in aquatic life. Four monitoring points were established to collect changes in the fauna and flora and the water quality, including conductivity, temperature, pH and oxygen concentration. Turbidity and chlorophyll measurements using a fluorimeter were also taken as well as the concentration of oxygen and luminosity during 24-hour cycles at the wetland exit point. The data collected revealed that the water entered the flooded area with a low level of oxygen concentration (about 10%) and left super-saturated (about 120%). The study also showed that during the period of monitoring, ephemeroptera, odonata and hemiptera species all increased in diversity.

In 2006 Andre Cunha from the Rio State University came to search for the Southern Woolly Spider Monkey, or Muriqui, Brachyteles arachnoides at REGUA, and was fortunate in making several good observations. In 2007 following further sightings, a paper was written and published in the scientific magazine Neotropical Primates entitled Further sightings of the muriqui population,(brachyteles arachnoides) at Reserva Ecologica de Guapiaçu – REGUA, Cachoeiras de Macacu – Rio de Janeiro, Brazil (Geoffroy, 1806). The Southern Woolly Spider Monkey used to be abundant throughout the Atlantic Forest of Brazil but is now listed as Endangered on the IUCN Red List and are thought to number less than 1,000 individuals through their entire remaining range. As REGUA acquires more land and the disturbance from hunting decreases, the number of sightings of Southern Woolly Spider Monkeys increases making REGUA one of the best sites to study this rare species.

Between 2007 and 2011 REGUA’s reputation continued to grow and REGUA received an average of three new research projects per year, and three new institutions (UNIFESO Centro Universitário Serra dos Órgãos; Universidade Estadual de Campinas (UNICAMP) and University of Leipzig) came to study at REGUA. Most of these studies focussed on vertebrate fauna (especially herpetology and ornithology) with single studies of palms and another on the geomorphology of the valley.

The year 2012 saw the highest annual number of eight new projects initiated, and REGUA hosted a remarkable 15 field courses and workshops. It is also interesting to note that the range of subjects has been widening into fresh water fish fauna, arthropods (beetles, flies and mosquitoes, ants, dragonflies), botany (Melastomataceae, epiphytes), reforestation ecotone ecology in permanent plots around the wetlands, carbon based studies and even projects in sociology (the impact of private nature reserves on local communities).

Some of these projects have also incorporated data provided by REGUA volunteers and visitors, and most new bird species are added by the many very experienced birders that visit the reserve. In addition to a number of papers and articles that have been published in journals and magazines, our volunteers have also contributed by publishing specialised books on the fauna of the region. The first of these, a guide to the identification of hawkmoths (Sphingidae), was published in 2011, and two further books on odonata and birds are scheduled for publication in 2015. Making more information on the incredible wildlife of the area available to a wider audience is one of our key objectives.