As Chief of the Research Section of the Divisão de Caça e Pesca of Ministério da Agricultura, heundertook many expeditions to regions of the country to study and catalog the animal and plant life of the Brazilian forests.
From the expeditions, many reports were published as articles and books about the conditions of individual species, as in As avoantes do Nordeste,[6] about the "eared" dove (Zenaida auriculata) of the Northeast of the country;[7][8][9][10][11] or the state of art of hunting and fishing in the five regions of Brazil;[12][13][14] museum's collections[15][16] with the taxidermist Antonio Domingos Aldrighi, former director of the Parque Nacional da Tijuca in Rio de Janeiro; and photo documented the fieldwork and the way of life of the population.
The expeditions were accompanied by employees of the Divisão de Caça e Pesca, of the Ministério da Agricultura, besides Aldrighi, the veterinarian Ítalo Desiderati Romeu, the taxidermy assistant José Anacleto and the collector and photographer Aggio Neto.
[17] From the expeditions, Aguirre collected many species for study and research, and from 19430 through 1950 created the Fauna Museum at the Quinta da Boa Vista, currently belonging to the Fundação Jardim Zoológico do Rio de Janeiro.
[21] During the 1960, as a researcher of CNPq, Aguirre undertook a long bibliographic review and several expeditions through the remaining blocks of Atlantic Forest, to study the conditions of life of the mono Brachyteles arachnoides (E. Geoffroy),[5] the Muriqui.
The obituary written by the Argentine researcher Enrique H. Bucher, his colleague and personal friend, published by the journal Ararajuba,[22][23] of the Sociedade Brasileira de Ornitologia,[24] relates not only the importance of his contribution for the preservation of the Brazilian fauna and flora, but also his biography.
He describes aspects of his personality that became part of this "distinct line of Latin-Americans scientists that, besides the difficulties imposed by the time and adversal environment in which they acted, were able to offer important achievements to the science of their countries, thanks to their enormous creativity and dedication" (Bucher, 1990, p. 123).
In 2004, scientific institutions, political association and civil society movements for nature preservation supported the "Álvaro Aguirre" Expedition through Rio Doce, in the state of Espírito Santo.
In 2010, the Instituto de Pesquisas da Mata Atlântica (IPEMA) produced the educational "kit" O Muriqui composed by a book,[29] a movie[30] and an itinerant exhibition for schools located in regions where the specie is.
The educational "kit" - O Muriqui - highlighted the pioneer researchers and conservationists working on species protection, such as Álvaro Aguirre, Feliciano Abdala, Russell Mittermeier, Célio Valle, Adelmar Coimbra Filho and Ibsen Câmara, documented with picture of the scientific meeting in 1982, at a lecture in Rio de Janeiro promoted by the Fundação Brasileira para a Conservação da Natureza.