Chris S. Elphick

NEST SITE SELECTION AND NESTING SUCCESS IN SALTMARSH BREEDING SPARROWS: THE IMPORTANCE OF NEST HABITAT, TIMING, AND STUDY SITE DIFFERENCES

Abstract We examined nest-site selection and nesting success in Saltmarsh Sharp-tailed (Ammodramus caudacutus) and Seaside Sparrows (A. maritimus), at seven sites in Connecticut. We found 160 Saltmarsh Sharp-tailed Sparrow nests and 23 Seaside Sparrow nests, and compared characteristics of their locations to each other and to random locations. We tracked success of all nests, quantified nest productivity and causes of nest losses, and tested for habitat differences between successful and unsuccessful nests. Saltmarsh Sharp-tailed Sparrows nested in higher than average locations, where the vegetation was taller and more dense than at random locations, where there was a deep layer of thatch, and where saltmeadow cordgrass (Spartina patens) dominated the vegetation. There was little evidence that habitat characteristics influenced the success of nesting birds, but the timing of nest initiation relative to spring tides was important. Seaside Sparrow nests occurred in even taller vegetation, that was more sparse than average and dominated by the tall form of smooth cordgrass (S. alterniflora). Habitat influenced the success of Seaside Sparrow nests, but timing did not; on average, successful nests occurred in taller vegetation. Model comparisons suggest that vegetation structure influences site selection more than species composition or inherent differences among marshes. Overall, our results indicate that nest flooding is a major threat to successful reproduction in both species, but they have different strategies to avoid flooding. Saltmarsh Sharp-tailed Sparrows time their reproduction to avoid especially high tides, while Seaside Sparrows avoid flooding spatially by nesting in tall vegetation.

Planning for Sea-Level Rise: Quantifying Patterns of Saltmarsh Sparrow (Ammodramus Caudacutus) Nest Flooding Under Current Sea-Level Conditions

ABSTRACT. Climate change and sea-level rise pose an imminent threat to the survival of coastal ecosystems, but the mechanisms by which animals inhabiting these areas may be affected by these changes are not well studied. During 2007–2009, we quantified the frequency of nest-flooding events at two salt marshes located in the northeastern United States that are of global importance to Saltmarsh Sparrow (Ammodramus caudacutus) conservation. Although nest flooding is a major cause of nest failure in this species, we lack a detailed understanding of exactly how flooding affects success, so it is difficult to determine the magnitude of the threat posed by sea-level rise. We tested whether variables associated with the timing of nest initiation, tide height, and flooding frequency can be used to estimate three aspects of nest fate: the probability of nest success, the probability of nest failure due to flooding, and the number of offspring lost to flooding. Of the 191 nests that we monitored, only 15% were never flooded and 18% were successful; the mean (± SD) number of flooding events observed per nest was 2.8 ± 2.1 (range: 0–10). The top-performing model for each measure of nest fate included variables related to tidal metrics, but model composition for the three measures differed in the importance of particular tide variables. Both tide height and flooding frequency emerged as important drivers of nest fate in this system. Saltmarsh Sparrow nests appear to be extremely vulnerable to even slight increases in sea level.

INVASIVE FRUITS, NOVEL FOODS, AND CHOICE: AN INVESTIGATION OF EUROPEAN STARLING AND AMERICAN ROBIN FRUGIVORY

Abstract We compared the feeding choices of an invasive frugivore, the European Starling (Sturnus vulgaris), with those of a native, the American Robin (Turdus migratorius). Using captive birds, we tested whether these species differ in their preferences when offered a choice between a native and an invasive fruit, and between a novel and a familiar food. We examined willingness to eat fruits of selected invasive plants and to select a novel food by measuring the time elapsed before feeding began. Both species demonstrated significant preferences for invasive fruits over similar native fruits in two of three choice tests. Both starlings and robins ate autumn olive (Elaeagnus umbellata) fruits significantly more willingly than Asiatic bittersweet (Celastrus orbiculatus). Starlings, but not robins when choosing between a novel and a familiar food, strongly preferred the familiar food. We found no differences in willingness of birds to eat a novel food when it was the only food available. These results suggest that some fleshy-fruited invasive plants may receive more dispersal services than native plants with similar fruits, and that different frugivores may be seed dispersers for different invasive plants.

Life-history and viability analysis of the endangered Hawaiian stilt

The Hawaiian stilt Himantopus mexicanus knudseni is an endangered, endemic subspecies of black-necked stilt. We present life-history data required to perform population viability analysis (PVA), and the results of a series of PVAs under two scenarios, treating (a) the subspecies as a single population, and (b) six subpopulations as a metapopulation. We performed sensitivity analyses on model parameters and used results to address various management options. Both basic models predicted that stilts would increase to fill available habitat with no chance of a significant decline. Catastrophe, maximum age, and density-dependent reproduction had little effect on population projections. Rapid declines in the probability of stilt populations persisting occurred when clutch failure rate or first-year mortality rate increased above 70%, or when adult mortality rate increased above 30%. Model predictions of mean population size at 200 years tracked changes in carrying capacity. If current conditions change such that rates of clutch failure or stilt mortality increase, population declines and eventual extinction becomes more likely. Managers, therefore, should maintain predator control, limit water level fluctuations, and maintain current habitat area. Downlisting is not warranted because wetland management and predator control are necessary for Hawaiian stilts to persist.

Assessing conservation trade-offs: identifying the effects of flooding rice fields for waterbirds on non-target bird species

Abstract I examined how winter flooding of post-harvest rice fields—a management practice used to benefit waterbirds—affects field use by other birds. In addition to waterbirds previously studied, I recorded 56 bird species in rice fields. Of these, five were more abundant in flooded fields, ten were more abundant in unflooded fields, no difference was detected for 19, and the remainder were too rare to draw any conclusions. Species that were more common in unflooded fields were all carnivorous or granivorous in winter, whereas species that were more common in flooded fields were mostly insectivores commonly associated with aquatic habitats. The net effects of the responses by individual species were fewer raptor species in flooded fields, but no difference in the species richness of other landbirds. Winter flooding potentially has negative effects for some birds, but has no discernible effects on most species studied and may benefit some passerines.

Comment on ''Ivory-billed Woodpecker (Campephilus principalis) Persists in Continental North America''

We reanalyzed video presented as confirmation that an ivory-billed woodpecker (Campephilus principalis) persists in Arkansas (Fitzpatrick et al., Reports, 3 June 2005, p. 1460). None of the features described as diagnostic of the ivory-billed woodpecker eliminate a normal pileated woodpecker (Dryocopus pileatus). Although we support efforts to find and protect ivory-billed woodpeckers, the video evidence does not demonstrate that the species persists in the United States.

First evidence of bryophyte diaspores in the plumage of transequatorial migrant birds.

Correlations between transequatorial migratory bird routes and bipolar biogeographic disjunctions in bryophytes suggest that disjunctions between northern and southern high latitude regions may result from bird-mediated dispersal; supporting evidence is, however, exclusively circumstantial. Birds disperse plant units (diaspores) internally via ingestion (endozoochory) or externally by the attachment of diaspores to the body (ectozoochory). Endozoochory is known to be the primary means of bird-mediated dispersal for seeds and invertebrates at local, regional, and continental scales. Data supporting the role of bird-mediated endozoochory or ectozoochory in the long distance dispersal of bryophytes remain sparse, however, despite the large number of bryophytes displaying bipolar disjunctions. To determine if transequatorial migrant shorebirds may play a role in the ectozoochory of bryophyte diaspores, we developed a method for screening feathers of wild birds. We provide the first evidence of microscopic bryophyte diaspores, as well as those from non-bryophyte lineages, embedded in the plumage of long distance transequatorial migrant birds captured in their arctic breeding grounds. The number of diaspores recovered suggests that entire migratory populations may be departing their northern breeding grounds laden with potentially viable plant parts and that they could thereby play significant roles in bipolar range expansions of lineages previously ignored in the migrant bird dispersal literature.

Why study birds in rice fields

Abstract. Rice (Oryza sativa) is one of the worlds most important crops. The crop is grown in at least 114 countries, occupies over 156 million ha of land annually, is a primary source of nutrition for over half the worlds human population and constitutes over a fifth of the global grain supply. Rice is generally grown under flooded conditions and, if managed appropriately, can provide important habitat for wetland species. Waterfowl, wading birds, shorebirds and other waterbirds use rice fields, foraging on a variety of prey, nesting in the crop and in fringing vegetation, and staging during migration. Conflicts also exist, with some cropping practices harmful to birds and some bird activity detrimental to yield production. Much early research on waterbirds in rice fields was conducted in Mediterranean Europe with only scattered work elsewhere. More recently, there has been a growing focus on the conservation value of rice fields, with studies from most of the major regions where rice is grown. The body of research has included: community studies of the range of birds that use rice fields, detailed studies of endangered species, behavioral studies of reproductive success, foraging ecology and movement, and applied studies of cropping techniques. As the worlds natural wetlands diminish, researchers studying waterbirds in rice fields are working to globalize interactions with each other. Also, some researchers are working closely with conservation groups and rice growers to identify ways to maximize the benefits of agricultural wetlands while minimizing the agronomic costs.

Effects of Landscape Features on Waterbird Use of Rice Fields

Abstract. Literature is reviewed to determine the effects of landscape features on waterbird use of fields in regions where rice (Oryza sativa) is grown. Rice-growing landscapes often consist of diverse land uses and land cover, including rice fields, irrigation ditches, other agricultural fields, grasslands, forests and natural wetlands. Numerous studies indicate that local management practices, such as water depth and timing of flooding and drawdown, can strongly influence waterbird use of a given rice field. However, the effects of size and distribution of rice fields and associated habitats at a landscape scale have received less attention. Even fewer studies have focused on local and landscape effects simultaneously. Habitat connectivity, area of rice, distance to natural wetlands, and presence and distance to unsuitable habitat can be important parameters influencing bird use of rice fields. However, responses to a given landscape vary with landscape structure, scale of analysis, among taxa and within taxa among seasons. A lack of multi-scale studies, particularly those extending beyond simple presence and abundance of a given species, and a lack of direct tests comparing the relative importance of landscape features with in-field management activities limits understanding of the importance of landscape in these systems and hampers waterbird conservation and management.

Management of Rice Fields for Birds during the Non-growing Season

Abstract. Fields planted with rice (Oryza sativa) are used by a wide variety of bird species during the non-growing season and play an important conservation role in many parts of the world. Management of fields affects the variety and number of birds that use them, and a thorough understanding of these issues could improve the conservation value of rice farming. The challenge for conservation practitioners is identifying management actions that provide benefits, without adverse impacts on crop production. Harvest method, post-harvest straw management, winter flooding, food supplementation and hunting all influence bird populations. Also, field preparation methods, organic farming and the management of field margins and drainage ditches, probably influence the conservation value of rice agriculture but have received less attention. Current knowledge of these issues is reviewed in order to identify management practices thought to have conservation benefits and highlight topics that warrant additional research.