Altitudinal movements and conservation of Bare-necked Umbrellabird <i>Cephalopterus glabricollis</i> of the Tilarán Mountains, Costa Rica

Chaves‐Campos, Johel; Arévalo, J. Edgardo; Araya, Mariamalia

doi:10.1017/s0959270903003046

Cited by 32 publications

(28 citation statements)

References 28 publications

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“…Several studies demonstrate that large fruit‐eating bird species such as hornbills in South‐East Asia and Africa, and toucans in the Neotropics are able to fly between forest patches of fragmented landscapes and have the potential to act as long‐distance seed dispersers (Kemp ; Powell & Bjork ; Holbrook & Smith ; Graham ; Chaves‐Campos, Arevalo & Araya ; Price ; Kays et al . ; Lenz et al .…”

Section: Introductionmentioning

confidence: 99%

Large frugivorous birds facilitate functional connectivity of fragmented landscapes

Mueller

Lenz

Caprano

et al. 2014

Journal of Applied Ecology

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Summary1. Quantifying ecosystem functions in spatially explicit ways is important for management decisions in increasingly fragmented landscapes. Between-patch dispersal of seeds by frugivores constitutes a key ecosystem function to ensure connectivity for fleshy-fruited plants. However, to date, methodological hurdles have limited our understanding of dispersal pathways on the landscape scale. 2. We made use of newly available tracking devices and combined movement data of 30 trumpeter hornbills Bycanistes bucinator with gut passage times and high-resolution habitat data in a fragmented forest landscape in South Africa. We identified each potential seed dispersal path and distinguished whether potential seed transport happened to a different forest patch (between-patch dispersal), within the same patch (within-patch dispersal) or into the habitat matrix (failed dispersal). To quantify functional landscape connectivity, we identified all possible between-patch connections and used graph networks to estimate landscape connectivity provided by hornbills. 3. Although potential between-patch dispersal events were rare (on average 7% compared to 20% failed dispersal and 73% within-patch dispersal), hornbills could cover distances of up to 15 km. Hornbills visited over 100 forest patches and connected a habitat network with an extent of about 50 km, which increased the potential functional connectivity of the landscape more than twofold. 4. We identified habitat patches that were critical stepping stones for seed dispersal pathways. Without these stepping stones, the network would likely disintegrate into separated components and lead to isolation of forest fragments. 5. Synthesis and applications. We showed that large frugivorous birds can greatly improve functional connectivity for fleshy-fruited plants across broad scales, linking habitat patches in fragmented forest landscapes. Combining high-resolution movement and landscape data in graph networks allows identifying seed dispersal pathways and critical stepping stones in fragmented landscapes. This approach addresses the general challenge of spatially explicit mapping of ecosystem services and can be widely incorporated in reserve design and landscape-level conservation planning.

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Section: Introductionmentioning

confidence: 99%

Large frugivorous birds facilitate functional connectivity of fragmented landscapes

Mueller

Lenz

Caprano

et al. 2014

Journal of Applied Ecology

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“…However, increasing evidence suggests that patterns of food availability are not sufficient to explain this behaviour (e.g. Soló rzano et al 2000;Chaves-Campos et al 2003;Boyle 2010). In 1969, Alexander Skutch speculated that tropical storms could affect the altitudinal migrations of birds (Skutch 1969).…”

Section: Introductionmentioning

confidence: 99%

Storms drive altitudinal migration in a tropical bird

2010

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Although migration is a widespread and taxonomically diverse behaviour, the ecological factors shaping migratory behaviour are poorly understood. Like other montane taxa, many birds migrate along elevational gradients in the tropics. Forty years ago, Alexander Skutch postulated that severe storms could drive birds to migrate downhill. Here, we articulate a novel mechanism that could link storms to mortality risks via reductions in foraging time and provide, to our knowledge, the first tests of this hypothesis in the White-ruffed Manakin (Corapipo altera), a small partially migratory frugivore breeding on the Atlantic slope of Costa Rica. As predicted, variation in rainfall was associated with plasma corticosterone levels, fat stores, plasma metabolites and haematocrit. By collecting data at high and low elevation sites simultaneously, we also found that high-elevation residents were more adversely affected by storms than low elevation migrants. These results, together with striking temporal capture patterns of altitudinal migrants relative to storms, provide, to our knowledge, the first evidence that weather-related risks incurred by species requiring high food intake rates can explain altitudinal migrations of tropical animals. These findings resolve conflicting evidence for and against food limitation being important in the evolution of this behaviour, and highlight how endogenous and exogenous processes influence life-history trade-offs made by individuals in the wild. Because seasonal storms are a defining characteristic of most tropical ecosystems and rainfall patterns will probably change in ensuing decades, these results have important implications for understanding the ecology, evolution and conservation of tropical animals.

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“…Some evidence supports the hypothesis of reciprocal variation in food abundance as an explanation for altitudinal migration (Wheelwright 1983;Solórzano et al 2000), but the evidence is inconclusive. For example, the timing and movement patterns of individual species can only partly be explained by seasonal peaks in fruit abundance (Rosselli 1994;Chaves-Campos et al 2003;Chaves-Campos 2004;Boyle 2010). Most importantly, in all the tropical forests in which species-level studies have been conducted, many sympatric, ecologically similar, and closely-related species do not migrate at all.…”

Section: Introductionmentioning

confidence: 99%

Why do some, but not all, tropical birds migrate? A comparative study of diet breadth and fruit preference

2010

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Annual migrations of birds profoundly influence terrestrial communities. However, few empirical studies examine why birds migrate, in part due to the difficulty of testing causal hypotheses in long-distance migration systems. Short-distance altitudinal migrations provide relatively tractable systems in which to test explanations for migration. Many past studies explain tropical altitudinal migration as a response to spatial and temporal variation in fruit availability. Yet this hypothesis fails to explain why some coexisting, closely-related frugivorous birds remain resident year-round. We take a mechanistic approach by proposing and evaluating two hypotheses (one based on competitive exclusion and the other based on differences in dietary specialization) to explain why some, but not all, tropical frugivores migrate. We tested predictions of these hypotheses by comparing diets, fruit preferences, and the relationships between diet and preference in closely-related pairs of migrant and resident species. Fecal samples and experimental choice trials revealed that sympatric migrants and residents differed in both their diets and fruit preferences. Migrants consumed a greater diversity of fruits and fewer arthropods than did their resident counterparts. Migrants also tended to have slightly stronger fruit preferences than residents. Most critically, diets of migrants more closely Electronic supplementary material The online version of this article (matched their preferences than did the diets of residents. These results suggest that migrants may be competitively superior foragers for fruit compared to residents (rather than vice versa), implying that current competitive interactions are unlikely to explain variation in migratory behavior among coexisting frugivores. We found some support for the dietary specialization hypothesis, propose refinements to the mechanism underlying this hypothesis, and discuss how dietary specialization might ultimately reflect past interspecific competition. We recommend that future studies quantify variation in nutritional content of tropical fruits, and determine whether frugivory is a consequence or a cause of migratory behaviour.

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Altitudinal movements and conservation of Bare-necked Umbrellabird Cephalopterus glabricollis of the Tilarán Mountains, Costa Rica

Cited by 32 publications

References 28 publications

Large frugivorous birds facilitate functional connectivity of fragmented landscapes

Large frugivorous birds facilitate functional connectivity of fragmented landscapes

Storms drive altitudinal migration in a tropical bird

Why do some, but not all, tropical birds migrate? A comparative study of diet breadth and fruit preference

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