Connectivity and Tropical Hummingbird Movement


  • Noelia L. Volpe,

  • Adam S. Hadley,

  • W. Douglas Robinson,

  • Matthew G. Betts

Translocation experiments, in which researchers displace animals, then monitor their movements to return home, are commonly used as tools to assess functional connectivity of fragmented landscapes. Yet we lack tests of whether movement behavior of translocated birds reflects natural behavior of unmanipulated birds. We compared the routine movement behavior of a tropical hummingbird (Phaethornis guy) to that of experimentally translocated individuals. Behaviors documented during translocation experiments reflected those observed during routine movements. Both translocated and non-translocated birds showed similar levels of preference for mature tropical forest and avoided movement across non-forested matrix and selected streams as movement corridors. Restricted movement of P. guy in fragmented landscapes may explain depressed plant reproduction in small, isolated fragments.

Figure Photo 1.

Adult Green Hermit Hummingbird (Phaethornis guy) with radio-transmitter attached to its back. We fed sugar-water to captured individuals to ensure recovery from the capture process. Nail polish applied to hummingbird foreheads aided in the identification of individuals. The attachment of the transmitter did not appear to affect the behavior of tagged individuals; we observed radio-tagged birds conducting normal behavior during foraging movements and breeding, including nesting. Photos by Noelia L. Volpe (top) and Matthew G. Betts (bottom).

Figure Photo 2.

Green Hermit feeding from a Heliconia tortuosa flower. This plant species is the main food source of P. guy and has been found to be sensitive to fragmentation. In our previous work (Hadley et al. 2014, Ecology) we observed reduced reproductive success of this plant species in small forest fragments. Changes in movement patterns by pollinators such as the Green Hermit might account for the observed effects. Photo by Matthew G. Betts.

Figure Photo 3.

Study area around the Las Cruces Biological Station. Agricultural development has led to a landscape consisting of forest fragments surrounded by an agricultural matrix of crops and cattle pastures. Green Hermits avoided non-forest matrix and selected riparian corridors while moving through the landscape. Photo by Noelia L. Volpe.

These photographs illustrate the article “Functional connectivity experiments reflect routine movement behavior of a tropical hummingbird species” by Noelia L. Volpe, Adam S. Hadley, W. Douglas Robinson, and Matthew G. Betts, scheduled to appear in Ecological Applications 24:2122–2131, December 2014.