In Ecuador A. f. fusciceps inhabits tropical and subtropical humid forests from 100 to 1,800 m Asl (Gavilánez-Endara 2006; Tirira 2007). In Colombia A. f. rufiventris inhabits dry forest, humid forest and cloud forest, occupying the greatest range of forest habitats of any of the Colombian spider monkeys (Hernández-Camacho and Cooper 1976).  Defler (2004) indicated that they range as high as 2,000-2,500 m Asl in the Cordilllera Occidental. In Panama, A. f. rufiventris is reported between 200-1,350 m Asl in pre-montane and montane forest, but have been also reported in lowland tropical rainforest, persisting in agricultural mosaics using only living fences or gallery forest (Méndez-Carvajal 2012).
The presence of A. f. fusciceps in a locality could be correlated with suitable habitat conditions such as continuous canopy cover and high abundance of large and tall trees (Gavilánez-Endara 2006; Estévez-Noboa 2009; Cueva and Pozo 2010; Moscoso 2010). These conditions are found mostly in mature and undisturbed forest. Nevertheless, this species has been recorded in old secondary forest, connected with continuous forest patches.  Occupancy modelling of the subspecies in a lowland evergreen forests (Tesoro Escondido) suggest that with enough primary forest it may be able to persist in a mosaic habitat (Spaan 2013). Altitude could be associated with low abundance of the subspecies (Madden y Albuja 1989; Shanee 2009; Moscoso 2010), therefore well preserved lowland forest harbors the healthiest populations of A. f. fusciceps.  

Spider monkeys travel and forage in the upper levels of the forest. They spend much time in the canopy and also use the middle and lower strata but are rarely seen in the understory. In accordance with their use of the highest levels of the forest, they are highly suspensory. When travelling they spend more time hanging from branches, brachiating, and climbing than they do walking or running on all fours. They are highly frugivorous and feed largely on the mature, soft parts of a very wide variety of fruits, which comprise 83% of their diet and are found mainly in the emergent trees and upper part of the forest canopy (Van Roosmalen and Klein 1988). They also eat young leaves and flowers (both especially at times of fruit shortage during the beginning of the dry season), young seeds, floral buds, pseudobulbs, aerial roots, bark, decaying wood, and honey, and very occasionally small insects such as termites and caterpillars (Van Roosmalen and Klein 1988; Tirira et al. 2014). They play a significant role as seed dispersers. Van Roosmalen (1985; Van Roosmalen and Klein 1988) found that A. paniscus was dispersing the seeds of at least 138 species (93.5% of all fruits species used) through their ingestion and subsequent defecation (endozoochory). A further 10 species were being dispersed by the monkeys carrying them off some distance from the tree before dropping them (exozoochory). In only 23 species were the seeds being ruined or eaten (seed predation). A study of diet of one individual A. fusciceps fusciceps living with a group of Alouatta palliata in a patch of forest in Ecuador (Moscoso 2010), revealed a high rate of ingestion of young leaves during the dry season (63%), followed by fruits (25% ), flowers (8%) and others (5%); while during the wet season fruits were the main item consumed (47%), followed by young leaves (42%) and others (11%).  Tapia (2013) reported that the fruits of Brosimum utile are the preferred item selected by A. f. fusciceps in Tesoro Escondido (Esmeraldas Province), followed by the fruits of Inga spp. and Pouroma chocoana.

There are two recognized subspecies:

Ateles fusciceps fusciceps is endemic to northwestern Ecuador from Esmeraldas Province (west of the Andes Mountain Range) to the northwest of Pichincha and Santo Domingo Provinces, extending to the western borders of Imbabura and Carchi Provinces. There are past reports of this species in the south, within the Colon Colonche Mountain Range (within Manabí, Guayas and Santa Elena Provinces), and westward on Chimborazo Province. A recent report of this subspecies has been made in the northwest of Manabí Province (Flavio Alfaro). Hernández-Camacho and Cooper (1976) suggested that A. f. fusciceps might occur in southern Colombia, south of the Río Mira, continuous with the populations in Ecuador, but no evidence has been forthcoming regarding this.

Ateles fusciceps rufiventris does not occur in Ecuador and is discontinuous with A. f. fusciceps. A. f. rufiventris ranges from the western cordillera of the Andes from south-western Colombia, northward on west side of the Río Cauca to eastern Panama (Cerro Pirre and the basin of the Río Bayano of the Pacific coast) (Rylands et al. 2006). The Cerro Pirre or the Río Tucutí mark the border with A. geoffroyi grisescens. In Colombia, A. f. rufiventris occurs throughout the Pacific lowlands except for Juradó in the north-western part of the Department of Chocó, supposedly the domain of A. g. grisescens (Hernández-Camacho and Cooper 1976; Defler, 2003, 2004). It occurs in the Urabá region in north-western Antioquia, Córdoba, Sucre, and northern Bolívar east to the lower Río Cauca along the western bank to south-central Antioquia. The most southerly record in Colombia is Barabacoas, Department of Nariño, and the most northerly is the southern bank of the Canal del Dique, Cartagena. Hernández-Camacho and Cooper (1976) believed that it formerly occurred as far north as Pendales. Although the historical distribution of A. f. rufiventris comprises large areas in the Colombian Chocó, many of these areas have been largely defaunated and only a few recent records of the species have been registered in the last decade, specifically in Montes de Maria, Bolivar, at Mutatá, Chonó and near Guapi.

In Panama, A. f. rufiventris occurs in Maje Mountain Chain, Darien National Park (Pirre, Boca de Cupe), Chucanti Nature Reserve, only for Darien and Panama provinces (Méndez-Carvajal, 2012; 2014).

This species is included in CITES Appendix II.

In Ecuador, Ateles fusciceps fusciceps has been considered Critically Endangered in the Red Book of Mammals of Ecuador since 2001 (Tirira et al. 2011) and included in the List of the World’s 25 Most Threatened Primate Species (2012-2014) (Tirira et al. 2014). It is protected in accordance with Resolution No. 143 of the Ministry of the Environment (Registro Oficial No. 6 of 23 January 2003) (Tirira et al. 2011), prohibiting hunting and commercialization throughout Ecuador for an indefinite period.

All studies conducted up to now on A.f. fusciceps recommend conservation actions focusing on unprotected lowland forest to the south and west of the Cotacachi-Cayapas Ecological Reserve, where population densities are greatest, the habitat conditions are good and hunting pressure is low (Moscoso 2010; Peck et al. 2011; Tirira, et al. 2011). If this area is protected, it could become a core area of healthy groups of the subspecies, capable of sustaining itself and become a source of genetic flow with individuals of other subpopulations in the north and south of the country. Some initiatives focused on research and conservation of the subspecies have been developed in Ecuador since 2005, firstly through PRIMENET (sustainable network for conservation of primates and habitat in NW Ecuador), and through ongoing projects of Proyecto Washu and the University of Sussex (since 2012). Proyecto Washu has started (2014) to conduct a reintroduction project in a locality where the species has become almost extinct (Mashpi Reserve, Pichincha Province). Nevertheless, the efforts need to continue and be strengthened in the future.

Tirira et al. (2011) recommend in the Red List of Mammals of Ecuador some conservation actions for the subspecies:

• Creation of an ecological corridor system between isolated patches connecting locations where the subspecies has been reported. It is important to strengthen forest connectivity between the main protected areas (Awa Ethnic and Forest Reserve and Cotacachi-Cayapas Ecological Reserve), but also between potential small subpopulations that exist along the northwest of Pichincha (such as Pachijal and Mindo-Nambillo Protected Forest, and reserves in Pedro Vicente Maldonado and San Miguel de los Bancos) and between the remnants of forest that joins Carchi, Imbabura and Esmeraldas Provinces.

• Development of suitable practices of landscape management that contribute to sustainable use of resources, minimizing the impact on primate populations and habitat.

• Evaluation of the effectiveness of protected areas the subspecies inhabits.

• Evaluation of the subspecies resilience to human impact, deforestation and hunting pressure, mainly within protected areas.

• Concrete measures to strengthen conservation efforts within protected forests.

• Continuation of a national campaign of environmental education to prevent illegal trade.

• Generation of data gathered in zoos and rescue centres on the reproduction, breeding and management of the subspecies ex-situ to create a network of reproduction ex-situ for future reintroduction programs.

It is also important to conduct research in potential areas of distribution of the species (such as Manabí and Pichincha Provinces) to confirm the presence of the species and take urgent measures for the conservation of these subpopulations.

The subspecies are recorded from the following protected areas:

Ateles fusciceps fusciceps

Ecuador

• Cotacachi-Cayapas Ecological Reserve (243,638 ha) (Tirira 2007)
• Los Cedros Protected Forest (Tirira 2007)
• Awá Ethnological Reserve (Tirira 2007)
• Awacachi Ecological Corridor (Francisco Prieto, com. pers. 2011)
• Ashiringa Protected Forest (Moscoso 2010)

Ateles fusciceps rufiventris

Colombia

• Los Katios Natural National Park (72,000 ha)
• Las Orquideas Natural National Park (32,000 ha)

In Panama the Fundación Pro-Conservación de los Primates Panameños (FCPP) is conducting a long term project in Chucanti Nature Reserve, Darien, using Orion Camera System (OCS) to monitor habitat use of this species, and other arboreal fauna interacting in this reserve; additional, environmental education is conducted by informal talks to local people, distributing t-shirts, and bookmarks with basic information about this species (Méndez-Carvajal 2012, 2014).

Ateles f. rufiventris occurs in Panama and Darien provinces, Darien National Park (5,970 km²), Majé Mountain Chain, Boca de Cupe, Pirre, and Chucantí Nature Reserve, Cerro Chucantí (Méndez-Carvajal 2012).

FCPP and the Panamanian Ministry of Environment listed this primate as Critically Endangered.