Territorial foraging behavior in the male Violet-capped Woodnymph is dependent on the density of patches of inflorescences of Heliconia spathocircinata Aristeg. (Heliconiaceae) in the Brazilian Atlantic forest

Abstract

Hummingbirds can vary their foraging strategies by adopting different behavior patterns. In Central America, the territorial behavior of these birds may be influenced by the floral resource availability in patches of Heliconia L. (Heliconiaceae) species. We investigated whether a similar pattern occurs in the South American species, Heliconia spathocircinata Aristeg., in a fragment of Atlantic forest in the state of Rio de Janeiro, Brazil, and whether agonistic interactions between the hummingbirds were correlated with the body weight. We conducted focal observations over two flowering seasons (2011/2012 and 2012/2013) in 159 patches of H. spathocircinata to evaluate whether territorial defense by the hummingbirds depends on floral resource availability (number of inflorescences per patch of 78.5 m 2), using a linear regression analysis. This patch area (territory size) was defined arbitrarily, based on the typical size of inflorescence patches found within the study area. The potential relationship between body weight and agonism was evaluated using a Pearson correlation. We recorded 55 different territories defended by Thalurania glaucopis (Gmelin, 1788) in patches containing between eight and 16 inflorescences. The number of times the T. glaucopis males defended their territories was influenced by the number of inflorescences per patch. Agonism was positively correlated with body weight only for intraspecific interactions in T. glaucopis. This indicates that the foraging behavior of the pollinator of the South American H. spathocircinata may be influenced directly by the available number of inflorescences in patches of this plant.

Florivory by the occupants of phytotelmata in flower parts can decrease host plant fecundity

“…The ecological and evolutionary implications of floral antagonism for ornithophilous pollination systems ( Gélvez-Zúñiga et al 2018 ) are thus an additional question that should be considered in future studies. The interaction between pollinating hummingbirds and Heliconia inflorescences has received much attention in studies of ecology and evolution ( Linhart 1973 ; Stiles 1975 ; Gill 1987 ; Temeles et al 2000 , 2013 ; Martén-Rodríguez et al 2011 ; Missagia and Verçoza 2011 ; Betts et al 2015 ; Missagia and Alves 2016 , 2017 ), although the results of our study indicate that this previous research has greatly underestimated the effects of florivory by the larval occupants of the inflorescence on both pollination (pre-seed stage) and the development of the fruits and seeds (post-seed stage). This is despite the fact that a large body of zoocentric data exists on insect communities of the phytotelmata of Heliconia inflorescences ( Skutch 1933 ; Seifert and Seifert 1976a , 1976 b; Seifert 1981 ; Lounibos et al 1987 ; Naeem 1988 , 1990 ; Richardson et al 2000 ; Richardson and Hull 2000 ; Meskens et al 2011 ; Benítez-Malvido et al 2016 ).…”

“…The bracts of H. spathocircinata may host the larvae of a number of different insect taxa ( Figure 2 ), including dipterans of the families Syrphidae and Stratiomyidae ( Fontenelle et al 2012 ; Missagia and Alves 2017 ). In southeastern Brazil, hummingbird pollinators have been observed visiting H. spathocircinata flowers ( Buzato et al 2000 ; Cruz et al 2006 ; Missagia and Verçoza 2011 ; Missagia and Alves 2017 ), and in some cases, the birds defend patches of inflorescences as territories ( Missagia and Alves 2016 ).…”

Patterns of territorial space use by Shining Sunbeams ( Aglaeactis cupripennis ), tropical montane hummingbirds

“…The relationship between resource acquisition and territory defense may produce different space‐use patterns by territory owners. For example, elevated levels of aggression and high visitation rates by resident owners are correlated with patches containing many flowers (Stiles , Wolf and Hainsworth , García‐Meneses and Ramsay , Missagia and Alves ). Territorial aggression also depends on the size of competitors and the extent of resource overlap (Lyon et al , Dearborn ), which may vary across seasons or with time of day (Stiles , Paton and Carpenter ).…”

Effects of the availability of floral resources and neighboring plants on nectar robbery in a specialized pollination system

“…Heliconia spathocircinata ( Figure 1A ), like other species of the genus and due to its capacity for vegetative propagation, forms clusters or floral patches containing a number of different inflorescences, primarily in riparian vegetation and in areas adjacent to trails and clearings ( Kress 1990 ). These floral patches are visited frequently by hummingbirds, which often establish their territories in these areas ( Missagia and Alves 2016 ). In the RebioUnião, the principal pollinator of H. spathocircinata is the Minute Hermit— Phaethornis idaliae (Bourcier and Mulsant 1856) ( Cruz et al 2006 ; Missagia 2019 ), which may also rob the nectar of this plant, given that it has been recorded robbing nectar from the congener Heliconia angusta in the RebioUnião (Cassio J. Oliveira, personal communication).…”

“…Flower density and species composition are especially important strategies to attract floral visitors with acute vision, such as hummingbirds, because these animals tend to be attracted by large floral patches ( Justino et al 2011 ; Missagia and Alves 2016 ) over long distances and will select these locations as their territories or as feeding stops along their flight paths, based on the value of the resources in the patch ( Maruyama et al 2013 ; Lanna et al 2017 ). From a zoocentric perspective, a visually attractive floral patch reflects a high resource availability ( Trombulak 1990 ) and the opportunity to feed from many flowers at low cost, in energetic terms, by flying short distances between flowers ( Temeles et al 2005 ; Tello-Ramos et al 2015 ).…”