Recent Research Papers

Ballentine, B. 2009. The ability to perform physically challenging songs predicts age and size in male swamp sparrows, Melospiza georgiana. Animal Behaviour 77: 973-978. PDF

Betts, M. G., Rodenhouse, N. L., Sillett, T. S., Doran, P. J. & Holmes, R. T. 2008. Dynamic occupancy models reveal within-breeding season movement up a habitat quality gradient by a migratory songbird. Ecography.

Colbeck, G. J., Gibbs, H. L., Marra, P. P., Hobson, K. & Webster, M. S. 2008. Phylogeography of a Widespread North American Migratory Songbird (Setophaga ruticilla). Journal of Heredity 99: 453-463.

Cruz-Angon, A., Sillett, T. S. & Greenberg, R. 2008. An Experimental Study of Habitat Selection by Birds in a Coffee Plantation. Ecology 89: 921-927. PDF

Davis, A. K., Diggs, N. E., Cooper, R. J. & Marra, P. P. 2008. Hematological Stress Indices Reveal no Effect of Radio-Transmitters on Wintering Hermit Thrushes. Journal of Field Ornithology 79: 293-297. AbstractRadio-telemetry is often used to track birds, and several investigators have examined the possible effects of radio-transmitters on birds. One approach to this question is to determine if transmitters induce physiological stress. Using hematological indicators of stress (heterophil-lymphocyte [H/L] ratios), studies of captive birds have revealed no evidence that radio-transmitters cause stress. However, studies in captivity may not reflect conditions faced by birds in the wild, especially during energetically demanding times, such as the overwintering period.We examined the possible effect of backpack-style transmitters on overwinteringHermit Thrushes (Catharus guttatus) in South Carolina by examining H/L ratios fromblood smears made before and after transmitter attachment. We captured and recaptured eight thrushes in an early winter period and 11 in a late winter period, and in both cases found that H/L ratios did not change after 1 mo of carrying transmitters. H/L ratios also did not differ significantly (in either trial) between thrushes with and without transmitters. Furthermore, thrushes that carried transmitters during both of our trials did not have higher final H/L ratios than those that carried transmitters during just one trial (the late winter). These results indicate that carrying backpack-style transmitters for 1 mo did not induce stress in overwintering Hermit Thrushes. These results are consistent with studies of captive birds, and provide support for the continued use of backpack radio-transmitters in this species, as long as weight recommendations are met. PDF

DeLuca, W. V., Studds, C. E., King, R. S. & Marra, P. P. 2008. Coastal urbanization and the integrity of estuarine waterbird communities: threshold responses and the importance of scale. Biological Conservation 141: 2669-2678.

Durrant, K. L., Marra, P. P., Colbeck, G. J., Gibbs, H. L., Hobson, K. A., Norris, D. R., Bernik, B., Lloyd, V. L. & Fleischer, R. C. 2008. Parasite assemblages distinguish populations of a migratory passerine on the breeding grounds. Journal of Zoology 274: 318-326.

Durrant, K. L., Marra, P. P., Fallon, S. M., Colbeck, G. J., Gibbs, H. L., Hobson, K. A., Norris, D. R., Bernik, B., Lloyd, V. L. & Fleischer, R. C. 2008. Parasite assemblages distinguish populations of a migratory passerine on its breeding grounds. Journal of Zoology 274: 318-326.

Gomez, A., Kilpatrick, A. M., Kramer, L. D., Dupuis II, A. P., Maffei, J. G., Goetz, S. J., Marra, P. P., Daszak, P. & Aguirre, A. A. 2008. Land use and West Nile virus seroprevalence in wild mammals. Emerging Infectious Diseases 14: 962-965.

Gordon, C. E., McGill, B., Ibarra-Nunez, G., Greenberg, R. & Perfecto, I. 2009. Simplification of a coffee foliage-dwelling beetle community under low-shade management. Basic and Applied Ecology 10: 246-254. PDF

Greenberg, R. , Perfecto, I. & Philpott, S. M. 2008. Introduction: Agroforests as Model Systems for Tropical Ecology. Ecology 89: 913-914. PDF

Greenberg, R. Bye-bye Blackbird. ZooGoer 37[4], 8-15. 2008. PDF

Greenberg, R., Kozlenko, A., Etterson, M. & Dietsch, T. 2008. Patterns of Density, Diversity, and the Distribution of Migratory Strategies in the Russian Boreal Forest Avifauna. Journal of Biogeography 35: 2049-2060. AbstractComparisons of the biotas in the Palaearctic and Nearctic have focused on limited portions of the two regions. The purpose of this study was to assess the geographic pattern in the abundance, species richness, and importance of different migration patterns of the boreal forest avifauna of Eurasia from Europe to East Asia as well as their relationship to climate and forest productivity. We further examine data from two widely separated sites in the New World to see how these conform to the patterns found in the Eurasian system. PDF

Greenberg, R., Olsen, B., Ballentine, B., Warner, S. & Danner, R. 2008. Temporal distribution of the Coastal Plain Swamp Sparrow: The importance of subspecies identification. Birding 40: 42-49.

Greenberg, R., Perfecto, I. & Philpott, S. 2008. Guest Editorial. Coffee: ecology in the marketplace. Frontiers in Ecology 115. PDF

Karubian, J., Sillett, T. S. & Webster, M. S. 2008. The Effects of Delayed Plumage Maturation on Aggression and Survival in Male Red-Backed Fairy-Wrens. Behavioral Ecology 19: 508-516.

LaDeau, S. L., Kilpatrick, A. M., Calder, K. & Marra, P. P. 2008. West Nile virus revisited: Consequences for North American ecology. BioScience 58: 937-946.

Langin, K. M., Marra, P. P., Nemeth, Z., Moore, F. R., Kyser, T. K. & Ratcliffe, L. M. 2009. Breeding latitude and timing of spring migration in songbirds crossing the Gulf of Mexico. Journal of Avian Biology 40(3):309-316. PDF

Liu, I. A., Lohr, B., Olsen, B. & Greenberg, R. 2008. Macrogeographic Vocal Variation in Subspecies of Swamp Sparrow. The Condor 110: 102-109. AbstractVariation in song can play a central role in species and subspecies recognition among birds. The ability of individuals to distinguish between songs of their own versus songs of a different subspecies potentially strengthens local adaptation of subspecific populations. We investigated the degree of vocal divergence and discrimination between two subspecies of Swamp Sparrow (Melospiza georgiana) to examine how variation in song could influence behavioral response. We recorded songs of Southern (M. g. georgiana) and Coastal Plain (M. g. nigrescens) Swamp Sparrow males in Maryland and Delaware, respectively, and analyzed variation in syllable composition, repertoire size, trill rate, and frequency bandwidth. In addition to describing differences in song characteristics, we performed an estimate of local song type diversity that predicted larger population repertoires in M. g. nigrescens. We then broadcast recordings to evaluate male territorial responses to song and found that males reacted more strongly to songs of their own subspecies than to songs of the other subspecies. The extent of song variation and discrimination suggests the possibility of continued divergence. Further tests may determine whether such results can be generalized beyond the populations studied to the subspecies level, and whether females as well as males differentiate between songs from separate subspecies. PDF

Mettke-Hoffmann, C. 2008. Context-specific neophilia and its consequences for innovations. Behavioral and Brain Sciences 30: 419. AbstractAccording to Ramsey and colleagues the main constituent psychological processes of innovation are response to novelty, exploration, and the ability to recognize a novel solution. I fully support this view but would like to point out that novelty reactions are often context-specific. I will expand on this and discuss the possible consequences of context-specific novelty reactions on the emergence of innovations.

Mettke-Hofmann, C., Lorentzen, S., Schlicht, E., Schneider, J. & Werner, F. 2009. Spatial neophilia and spatial neophobia in resident and migratory warblers (Sylvia). Ethology 115: 482-492. PDF

Newhouse, M., Marra, P. P. & Johnson, L. S. 2008. Reproductive Success of House Wrens in Suburban and Rural Land-Use Areas. The Wilson Journal of Ornithology 120: 99-104.

Olsen, B., Felch, J., Greenberg, R. & Walters, J. 2008. Causes of reduced clutch size in a tidal marsh endemic. Oecologia 158: 421-435. AbstractWe tested three hypotheses of clutch size variation in two subspecies of the swamp sparrow (Melospiza georgiana georgiana and M. g. nigrescens). Swamp sparrows follow the pattern of other estuarine endemics, where clutch size is smaller among tidal salt marsh populations (M. g. nigrescens) than their closest inland relatives (M. g. georgiana). Our results support predation risk and temperature, but not adult survival, as explanations of this pattern in swamp sparrows. Coastal nests were twice as likely to fail as inland nests, and parental activity around the nest site was positively related to clutch size at both sites. When brood size was controlled for, coastal adults visited nests less often and females vocalized less frequently during visits than inland birds, which may decrease nest detectability to predators. Coastal parents waited longer than inland birds to feed offspring in the presence of a model nest predator, but there was no difference in their response to models of predators of adults, as would be expected if coastal birds possessed increased longevity. Additionally, coastal females laid more eggs than inland females over a single season, following a within-season bet-hedging strategy rather than reducing within-season investment. Coastal territories experienced ambient air temperatures above the physiological zero of egg development more often, and higher temperatures during laying correlated with smaller clutches and increased egg inviability among coastal birds. Similar effects were not seen among inland nests, where laying temperatures were generally below physiological zero. Both subspecies showed an increase in hatching asynchrony and a decrease in apparent incubation length under high temperatures. Coastal individuals, however, showed less hatching asynchrony overall despite higher temperatures. Both air temperatures during laying and predation risk could potentially explain reduced clutch size in not only coastal plain swamp sparrows, but also other tidal marsh endemics. PDF

Olsen, B., Greenberg, R., Fleischer, R. & Walters, J. 2008. Extrapair paternity in the swamp sparrow, Melospiza georgiana: Male access or female preference? Behavioural Ecology and Sociobiology. AbstractOver the past two decades, the combination of molecular and field methods has revealed considerable variation in the level of extrapair fertilizations among socially monogamous birds. Models predicting extrapair young range in scale from a single population to multiple Orders, and there is no single, unifying theory for these reproductive tactics. We investigated proximate explanations of extrapair fertilizations in two subspecies of the swamp sparrow, Melospiza georgiana georgiana and Melospiza georgiana nigrescens, across a range of social and environmental conditions. The presence of extrapair young was best predicted by the size of two male plumage badges (one correlated with parental care and one with territorial aggression) relative to the badge size of their immediate neighbors, the interaction of these two measures, mean territory size, and the maximum size of the aggression badge among neighbors. The size of the male’s parental care badge (relative to neighbors) was negatively correlated with the probability of lost paternity. The relative size of the aggression badge was positively correlated with the presence of extrapair young when the parental care badge was small and negatively correlated when the badge was large. Controlling for these crown measures, males with larger territories were less likely to suffer losses in paternity. There was no effect of breeding density, breeding synchrony, their interaction, subspecies, or weather during the fertile period on the presence of extrapair young. These results suggest that female preference for males that provide more parental care (or preference for genes that convey this trait) plays a dominant role in extrapair interactions among swamp sparrows. Models based on female assessments of relative mate quality offer a promising explanation of patterns in extrapair fertilizations among bird species. PDF

Peluc, S. I., Sillett, T. S., Rotenberry, J. T. & Ghalambor, C. K. 2008. Adaptive plasticity in nest site selection in response to increased predation risk. Behavioral Ecology 19: 830-835. AbstractAvian nest site selection and levels of parental care require assessments of numerous fitness costs and benefits. Nest site selection in open cup–nesting species is considered a relatively conservative trait; most species and genera are confined to nesting within particular vegetation strata. The nesting stratum further determines risk to nest predation, the principal cause of reproductive failure. We document predator-induced plasticity in nest site placement and levels of parental care in orange-crowned warblers (Vermivora celata) on an island lacking avian nest predators. We show a shift from ground nesting, characteristic of mainland populations, to off-ground nesting that appears adaptive relative to higher predation levels of ground nests. By altering the perceived nest predation risk via experimental introduction of a model avian predator prior to nest building, we demonstrate that warblers shift nest sites to more concealed ground locations. Moreover, warblers differentially adjust nest visits to feed nestlings in the presence of the predator: reducing feeding more at less concealed off-ground nests than at more concealed ground ones. Both shifts in nest site placement and feeding rate adjustments suggest adaptive phenotypic plasticity in response to increased perceived predation risk, providing evidence that birds continuously assess variation in the fitness costs and benefits of their behavioral decisions. PDF

Philpott, S. M., Arendt, W. J., Armbrecht, I., Bichier, P., Diestch, T. V., Gordon, C., Greenberg, R., Perfecto, I., Reynoso-Santos, R., Soto-Pinto, L., Tejeda-Cruz, C., Williams-Linera, G., Valenzuela, J. & Zolotoff, J. M. 2008. Biodiversity Loss in Latin American Coffee Landscapes: Review of the Evidence on Ants, Birds, and Trees. Conservation Biology 22: 1093-1105. PDF

Reudink, M. W., Marra, P. P., Boag, P. T. & Ratcliffe, L. M. 2009. Plumage colouration predicts paternity and polygyny in the American redstart. Animal Behaviour 77: 495-501.

Reudink, M. W., Marra, P. P., Langin, K. M., Studds, C. E., Kyser, T. K. & Ratcliffe, L. M. 2008. Molt-migration in the American Redstart (Setophaga ruticilla) revisited: Explaining variation in feather delta D signatures. Auk 125: 742-746.

Reudink, M. W., Marra, P., Kyser, T. K., Boag, P., Langin, K. & Ratcliffe, L. 2009. Non-breeding season events influence sexual selection in a long-distance migratory bird. Proceedings of the Royal Society B: Biological Sciences 276: 1619-1626. AbstractThe study of sexual selection has traditionally focused on events and behaviours immediately surrounding copulation. In this study, we examine whether carry-over effects from the non-breeding season can influence the process of sexual selection in a long-distance migratory bird, the American redstart (Setophaga ruticilla). Previous work on American redstarts demonstrated that overwintering in a high-quality habitat influences spring departure dates from the wintering grounds, advances arrival dates on the breeding grounds and increases apparent reproductive success. We show that the mixed-mating strategy of American redstarts compounds the benefits of overwintering in high-quality winter habitats. Males arriving to breed in Canada from high-quality winter habitats arrive earlier than males from poor-quality habitats, resulting in a lower probability of paternity loss, a higher probability of achieving polygyny and ultimately higher realized reproductive success. Such results suggest that the process of sexual selection may be influenced by events interacting throughout the annual cycle.

Reudink, M. w., Studds, C. E., Kyser, T. K., Marra, P. P. & Ratcliffe, L. M. 2009. Plumage brightness predicts non-breeding season territory quality in a long-distance migratory songbird. Journal of Avian Biology 40: 34-41.

Rice, R. A. 2008. Agricultural intensification within agroforestry: The case of coffee and wood products. Agriculture, Ecosystems and Environment.

Rice, R. A. Drinking Green. ZooGoer 37[4], 15-23. 2008. AbstractCompared to the environmental and conservation value as refuges for biodiversity, less is known about the social and economic value of shaded coffee systems. The agroforestry system can serve as a source of non-coffee products for diverse purposes. This study focuses on the role of shade trees in smallholder coffee farms, examining the wood products derived from the shaded coffee system. Data presented from surveys with 185 growers in Peru and 153 growers in Guatemala show that the consumption and sale of all non-coffee products account for a fifth to a third of the total value realized from the agroforestry system. Fuelwood and construction materials account for much of this value. Differences seen between countries can be traced to agricultural intensification – the degree to which the coffee agroforestry system is ‘‘technified’’ (i.e., managed with a reduced shade tree cover and diversity, high-yielding cultivars, agrochemical inputs, etc.) – as well as the relative demand for wood resources and farmers’ access to natural forest systems. PDF

Ryder, T. B. & Wolfe, J. D. 2009. The current state of knowledge on molt and plumage sequences in selected neotropical bird families: a review. Ornitologia Neotropical 20: 1-18.

Ryder, T. B., Parker, P. G., Blake, J. G. & Loiselle, B. A. 2009. It Takes Two to Tango: Reproductive Skew and Social Correlates of Male Mating Success in a Lek-Breeding Bird. Proceedings of the Royal Society B: Biological Sciences 276: 2377-2384.

Salgado-Ortiz, J., Marra, P. P., Sillett, T. S. & Robertson, R. J. 2008. Breeding Ecology of the Mangrove Warbler (Dendroica petechia Bryanti) and Comparative Life History of the Yellow Warbler Subspecies Complex. The Auk 125: 402-410.

Smith, J. A. M., Reitsma, L. R., Rockwood, L. L. & Marra, P. P. 2008. Roosting behavior of a Neotropical migrant songbird, the northern waterthrush Seiurus noveboracensis, during the non-breeding season. Journal of Avian Biology 39: 460-465. PDF

Studds, C. E., Kyser, T. K. & Marra, P. P. 2008. Natal dispersal drive by environmental conditions interacting across the annual cycle of a migratory songbird. Proceedings of the National Academy of Sciences 105: 2929-2933.

Van Bael, S. A., Philpott, S. M., Greenberg, R., Bichier, P., Barber, N. A., Mooney, K. A. & Gruner, D. S. 2008. Birds as Predators in Tropical Agroforestry Systems. Ecology 89: 928-934. PDF