Thomas E. Martin

United States Geological Survey, Reston, Virginia, United States

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Publications (96)449.82 Total impact

  • Penn Lloyd · Thomas E. Martin
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    ABSTRACT: Slow life histories are characterized by high adult survival and few offspring that are thought to allow increased investment per offspring to increase juvenile survival. Consistent with this pattern, south temperate zone birds are commonly longer-lived and have fewer young than north temperate zone species. However, comparative analyses of juvenile survival, including during the first few weeks post-fledging period when most juvenile mortality occurs, are largely lacking. We combined our measurements of fledgling survival for eight passerines in South Africa with estimates from published studies of 57 north and south temperate zone songbird species to test three predictions: first, that fledgling survival increases with length of development time in the nest; second, that fledgling survival increases with adult survival and reduced brood size controlled for development time; and third, that south temperate zone species, with their higher adult survival and smaller brood sizes, exhibit higher fledgling survival than north temperate zone species controlled for development time. We found that fledgling survival was higher among south temperate zone species and generally increased with development time and adult survival within and between latitudinal regions. Clutch size did not explain additional variation, but was confounded with adult survival. Given the importance of age-specific mortality to life history evolution, understanding the causes of these geographic patterns of mortality is important. This article is protected by copyright. All rights reserved.
    No preview · Article · Oct 2015 · Ibis
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    Riccardo Ton · Thomas E. Martin
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    ABSTRACT: 1.Variation in post-natal growth rates is substantial among organisms and especially strong among latitudes because tropical and south temperate species typically have slower growth than north-temperate relatives. Metabolic rate is thought to be a critical mechanism underlying growth rates after accounting for allometric effects of body mass. However, comparative tests on a large spatial scale are lacking, and the importance of metabolism for growth rates remains unclear both within and particularly across latitudes.2.Songbirds exhibit strong interspecific variation in growth rates across geographic space, although within latitudes an association between metabolic rate and growth rate has not always been observed. Moreover, the hypothesis that differences in growth rates across latitudes reflect underlying differences in metabolism is untested. Here we investigate these possibilities across north temperate, south temperate and tropical study sites.3.Phylogenetic analyses showed that, for a given body mass, metabolic rates of north temperate nestlings were higher than tropical and south temperate species. Metabolic rates controlled for body mass correlated with post-natal growth rates both within and among latitudes. Offspring body mass explained substantial residual variation in growth rates as expected under classic allometric theory.4.Our results suggest that variation in metabolic rates has an important influence on broad patterns of avian growth rates at a global scale. We suggest further studies that address the ecological and physiological costs and consequences of variation in metabolism and growth rates.This article is protected by copyright. All rights reserved.
    Full-text · Article · Sep 2015 · Functional Ecology
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    Thomas E. Martin · Juan C. Oteyza · Andy J. Boyce · Penn Lloyd · Riccardo Ton
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    ABSTRACT: Parental behavior and effort vary extensively among species. Life-history theory suggests that age-specific mortality could cause this interspecific variation, but past tests have focused on fecundity as the measure of parental effort. Fecundity can cause costs of reproduction that confuse whether mortality is the cause or the consequence of parental effort. We focus on a trait, parental allocation of time and effort in warming embryos, that varies widely among species of diverse taxa and is not tied to fecundity. We conducted studies on songbirds of four continents and show that time spent warming eggs varies widely among species and latitudes and is not correlated with clutch size. Adult and offspring (nest) mortality explained most of the interspecific variation in time and effort that parents spend warming eggs, measured by average egg temperatures. Parental effort in warming eggs is important because embryonic temperature can influence embryonic development period and hence exposure time to predation risk. We show through correlative evidence and experimental swapping of embryos between species that parentally induced egg temperatures cause interspecific variation in embryonic development period. The strong association of age-specific mortality with parental effort in warming eggs and the subsequent effects on embryonic development time are unique results that can advance understanding of broad geographic patterns of life-history variation.
    Full-text · Article · May 2015 · The American Naturalist
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    ABSTRACT: Clutch size commonly decreases with increasing elevation among temperate-zone and subtropical songbird species. Tropical songbirds typically lay small clutches, thus the ability to evolve even smaller clutch sizes at higher elevations is unclear and untested. We conducted a comparative phylogenetic analysis using data gathered from the literature to test whether clutch size varied with elevation among forest passerines from three tropical biogeographic regions—the Venezuelan Andes and adjacent lowlands, Malaysian Borneo, and New Guinea. We found a significant negative effect of elevation on variation in clutch size among species. We found the same pattern using field data sampled across elevational gradients in Venezuela and Malaysian Borneo. Field data were not available for New Guinea. Both sets of results demonstrate that tropical montane species across disparate biogeographic realms lay smaller clutches than closely related low-elevation species. The environmental sources of selection underlying this pattern remain uncertain and merit further investigation.
    Full-text · Article · Apr 2015 · The Auk
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    ABSTRACT: Turnover in animal species along vegetation gradients is often assumed to reflect adaptive habitat preferences that are narrower than the full gradient. Specifically, animals may decline in abundance where their reproductive success is low, and these poor-quality locations differ among species. Yet habitat use does not always appear adaptive. The crucial tests of how abundances and demographic costs of animals vary along experimentally manipulated vegetation gradients are lacking. We examined habitat use and nest predation rates for 16 bird species that exhibited turnover with shifts in deciduous and coniferous vegetation. For most bird species, decreasing abundance was associated with increasing predation rates along both natural and experimentally modified vegetation gradients. This landscape-scale approach strongly supports the idea that vegetation-mediated effects of predation are associated with animal distributions and species turnover.
    Full-text · Article · Mar 2015 · Ecology
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    Full-text · Dataset · Mar 2015
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    ABSTRACT: Abstract Growth and development rates may result from genetic programming of intrinsic processes that yield correlated rates between life stages. These intrinsic rates are thought to affect adult mortality probability and longevity. However, if proximate extrinsic factors (e.g., temperature, food) influence development rates differently between stages and yield low covariance between stages, then development rates may not explain adult mortality probability. We examined these issues based on study of 90 songbird species on four continents to capture the diverse life-history strategies observed across geographic space. The length of the embryonic period explained little variation (ca. 13%) in nestling periods and growth rates among species. This low covariance suggests that the relative importance of intrinsic and extrinsic influences on growth and development rates differs between stages. Consequently, nestling period durations and nestling growth rates were not related to annual adult mortality probability among diverse songbird species within or among sites. The absence of a clear effect of faster growth on adult mortality when examined in an evolutionary framework across species may indicate that species that evolve faster growth also evolve physiological mechanisms for ameliorating costs on adult mortality. Instead, adult mortality rates of species in the wild may be determined more strongly by extrinsic environmental causes.
    No preview · Article · Mar 2015 · The American Naturalist
  • Daniel Muñoz · Thomas E. Martin
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    ABSTRACT: The Spotted Barbtail (Furnariidae) is poorly studied but shows some extreme traits for a tropical passerine. We located and monitored 155 nests to study this species for 7 years in an Andean cloud forest in Venezuela. Spotted Barbtails have an unusually long incubation period of 27.2 ± 0.16 days, as a result of very long (3–6 hr) off-bouts even though both adults incubate. The long off-bouts yield low incubation temperatures for embryos and are associated with proportionally large eggs (21% of adult mass). They also have a long nestling period of 21.67 ± 0.33 days, and a typical tropical brood size of two. The slow growth rate of the typical broods of two is even slower in broods artificially reduced to one young. Nonetheless, the young stay in the nest long enough to achieve wing lengths that approach adult size.
    No preview · Article · Dec 2014 · The Wilson Journal of Ornithology
  • Thomas E. Martin
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    ABSTRACT: Resource selection specialization may increase vulnerability of populations to environmental change. One environmental change that may negatively impact some populations is the broad decline of quaking aspen Populus tremuloides, a preferred nest tree of cavity-nesting organisms who are commonly limited by nest-site availability. However, the long-term consequences of this habitat change for cavity-nesting bird populations are poorly studied.I counted densities of woody plants and eight cavity-nesting bird species over 29 years in 15 high elevation riparian drainages in Arizona, USA. I also studied nest tree use and specialization over time based on 4946 nests across species.Aspen suffered a severe decline in availability over time, while understorey woody plants and canopy deciduous trees also declined. The decline of plants resulted from increased elk Cervus canadensis browsing linked to declining snowfall.Woodpeckers exhibited very high specialization (>95% of nests) on aspen for nesting, and densities of all six species declined with aspen over time. Mountain chickadees Poecile gambeli and house wrens Troglodytes aedon exhibited increasingly less specialization on aspen. Chickadees strongly increased in density over time, despite a relatively high specialization on aspen. House wren densities declined moderately over time, but nest box addition experiments demonstrated that nest-site availability was not limiting their population. House wren densities increased with understorey vegetation recovery in elk exclosures via increased generality of nest site use, demonstrating that the decline in understorey vegetation on the broader landscape was the cause of their population decline.Synthesis and applications. Management should target species that specialize in resource selection on a declining resource. Species with greater resource selection generalization can reduce population impacts of environmental change. Resource generalization can allow a species like the wren to take advantage of habitat refuges, such as those provided by the elk exclosures. Yet, resource generalization cannot offset the negative impacts of broad-scale declines in habitat quality on the landscape, as demonstrated by the general decline of wrens. Ultimately, aspen is an important habitat for biodiversity, and land management programs that protect and aid recovery of aspen habitats may be critical.This article is protected by copyright. All rights reserved.
    No preview · Article · Nov 2014 · Journal of Applied Ecology
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    Penn Lloyd · Fitsum Abadi · Res Altwegg · Thomas E. Martin
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    ABSTRACT: Life history theory predicts an inverse relationship between annual adult survival and fecundity. Globally, clutch size shows a latitudinal gradient among birds, with south temperate species laying smaller clutches than north temperate species, but larger clutches than tropical species. Tropical birds often have higher adult survival than north temperate birds associated with their smaller clutches. However, the prediction that tropical birds should also have higher adult survival than south temperate birds because of smaller clutch sizes remains largely untested. We measured clutch size and apparent annual breeding adult survival for 17 south temperate African species to test two main predictions. First, we found strong support for a predicted inverse relationship between adult survival and clutch size among the south temperate species, consistent with life-history theory. Second, we compared our clutch size and survival estimates with published estimates for congeneric tropical African species to test the prediction of larger clutch size and lower adult survival among south temperate than related tropical species. We found that south-temperate species laid larger clutches, as predicted, but had higher, rather than lower, apparent adult survival than related tropical species. The latter result may be an artefact of different approaches to measuring survival, but the results suggest that adult survival is generally high in the south temperate region and raises questions about the importance of the cost of reproduction to adult survival.
    Full-text · Article · Sep 2014 · Journal of Avian Biology
  • Thomas E Martin
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    ABSTRACT: Abstract Causes of evolved differences in clutch size among songbird species remain debated. I propose a new conceptual framework that integrates aspects of traditional life-history theory while including novel elements to explain evolution of clutch size among songbirds. I review evidence that selection by nest predation on length of time that offspring develop in the nest creates a gradient in offspring characteristics at nest leaving (fledging), including flight mobility, spatial dispersion, and self-feeding rate. I postulate that this gradient has consequences for offspring mortality rates and parental energy expenditure per offspring. These consequences then determine how reproductive effort is partitioned among offspring, while reproductive effort evolves from age-specific mortality effects. Using data from a long-term site in Arizona, as well as from the literature, I provide support for hypothesized relationships. Nestling development period consistently explains fledgling mortality, energy expenditure per offspring, and clutch size while accounting for reproductive effort (i.e., total energy expenditure) to thereby support the framework. Tests in this article are not definitive, but they document previously unrecognized relationships and address diverse traits (developmental strategies, parental care strategies, energy requirements per offspring, evolution of reproductive effort, clutch size) that justify further investigations of hypotheses proposed here.
    No preview · Article · Mar 2014 · The American Naturalist
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    Full-text · Article · Jul 2013 · Science
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    Cameron K Ghalambor · Susana I Peluc · Thomas E Martin
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    ABSTRACT: Predation can be an important agent of natural selection shaping parental care behaviours, and can also favour behavioural plasticity. Parent birds often decrease the rate that they visit the nest to provision offspring when perceived risk is high. Yet, the plasticity of such responses may differ among species as a function of either their relative risk of predation, or the mean rate of provisioning. Here, we report parental provisioning responses to experimental increases in the perceived risk of predation. We tested responses of 10 species of bird in north temperate Arizona and subtropical Argentina that differed in their ambient risk of predation. All species decreased provisioning rates in response to the nest predator but not to a control. However, provisioning rates decreased more in species that had greater ambient risk of predation on natural nests. These results support theoretical predictions that the extent of plasticity of a trait that is sensitive to nest predation risk should vary among species in accordance with predation risk.
    Full-text · Article · May 2013 · Biology letters
  • Elena Arriero · Ania Majewska · Thomas E. Martin
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    ABSTRACT: 1. Variation in ontogeny and strength of immune defence mechanisms can be integrally related to variation in life-history strategies and determined by trade-offs during development. However, little is known about the ontogeny of immune function in wild birds, especially in altricial birds and in a comparative context across altricial species with diverse life-history strategies. 2. In this study, we examined the ontogeny of constitutive immunity in a group of 22 passerine species sampled in tropical Venezuela and north temperate Arizona. 3. Our results show activity of constitutive components of the immune defence at 1—3 days posthatching and an increase in immune activity with age. Interspecific variation in immune activity at hatching was mainly explained by extrinsic factors mediated by the mother (egg size and egg temperature), suggesting an important role of maternal effects on offspring immunity at hatching. In contrast, the increase in agglutination activity with age suggests that immune function in older nestlings reflects intrinsic development. The increase in immune activity was greater in species that hatched with lower initial levels, and was somewhat negatively related to growth rate across species. 4. Our results suggest slower intrinsic development of immune function may be compensated by larger maternal contributions. Slower intrinsic development of immune function, in turn, may reflect a trade-off with faster somatic growth. Our study highlights the importance of both maternal (extrinsic) and endogenous (intrinsic) contributions to variation in immune function across altricial species that may reflect an important axis of developmental strategies.
    No preview · Article · Apr 2013 · Functional Ecology
  • Thomas E Martin · Riccardo Ton · Alina Niklison
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    ABSTRACT: Intrinsic processes are assumed to underlie life history expression and trade-offs, but extrinsic inputs are theorised to shift trait expression and mask trade-offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass-specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade-off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade-offs across species.
    No preview · Article · Mar 2013 · Ecology Letters
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    Sonya K Auer · Thomas E Martin
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    ABSTRACT: Climate change can modify ecological interactions, but whether it can have cascading effects throughout ecological networks of multiple interacting species remains poorly studied. Climate-driven alterations in the intensity of plant-herbivore interactions may have particularly profound effects on the larger community because plants provide habitat for a wide diversity of organisms. Here we show that changes in vegetation over the last 21 years, due to climate effects on plant-herbivore interactions, have consequences for songbird nest site overlap and breeding success. Browsing-induced reductions in the availability of preferred nesting sites for two of three ground nesting songbirds led to increasing overlap in nest site characteristics among all three bird species with increasingly negative consequences for reproductive success over the long term. These results demonstrate that changes in the vegetation community from effects of climate change on plant-herbivore interactions can cause subtle shifts in ecological interactions that have critical demographic ramifications for other species in the larger community.
    Full-text · Article · Feb 2013 · Global Change Biology
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    Elliott W R Parsons · John L Maron · Thomas E Martin
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    ABSTRACT: Heavy herbivory by ungulates can substantially alter habitat, but the indirect consequences of habitat modification for animal assemblages that rely on that habitat are not well studied. This is a particularly important topic given that climate change can alter plant-herbivore interactions. We explored short-term responses of small mammal communities to recent exclusion of Rocky Mountain elk (Cervus elaphus) in high-elevation riparian drainages in northern Arizona, where elk impacts on vegetation have increased over the past quarter century associated with climate change. We used 10-ha elk exclosures paired with unfenced control drainages to examine how browsing influenced the habitat use, relative abundance, richness and diversity of a small mammal assemblage. We found that the small mammal assemblage changed significantly after 5 years of elk exclusion. Relative abundance of voles (Microtus mexicanus) increased in exclosure drainages, likely due to an increase in habitat quality. The relative abundances of woodrats (Neotoma neomexicana) and two species of mice (Peromyscus maniculatus and P. boylii) decreased in the controls, while remaining stable in exclosures. The decline of mice in control drainages was likely due to the decline in shrub cover that they use. Thus, elk exclusion may have maintained or improved habitat for mice inside the exclosures while habitat quality and mouse abundance both declined outside the fences. Finally, small mammal species richness increased in the exclosures relative to the controls while species diversity showed no significant trends. Together, our results show that relaxation of heavy herbivore pressure by a widespread native ungulate can lead to rapid changes in small mammal assemblages. Moreover, exclusion of large herbivores can yield rapid responses by vegetation that may enhance or maintain habitat quality for small mammal populations.
    Preview · Article · Nov 2012 · Journal of Animal Ecology
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    Yi-Ru Cheng · Thomas E Martin
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    ABSTRACT: Different body components are thought to trade off in their growth and development rates, but the causes for relative prioritization of any trait remains a critical question. Offspring of species at higher risk of predation might prioritize development of locomotor traits that facilitate escaping risky environments over growth of mass. We tested this possibility in 12 altricial passerine species that differed in their risk of nest predation. We found that rates of growth and development of mass, wings, and endothermy increased with nest predation risk across species. In particular, species with higher nest predation risk exhibited relatively faster growth of wings than of mass, fledged with relatively larger wing sizes and smaller mass, and developed endothermy earlier at relatively smaller mass. This differential development can facilitate both escape from predators and survival outside of the nest environment. Tarsus growth was not differentially prioritized with respect to nest predation risk, and instead all species achieved adult tarsus size by age of fledging. We also tested whether different foraging modes (aerial, arboreal, and ground foragers) might explain the variation of differential growth of locomotor modules, but we found that little residual variation was explained. Our results suggest that differences in nest predation risk among species are associated with relative prioritization of body components to facilitate escape from the risky nest environment.
    Full-text · Article · Sep 2012 · The American Naturalist
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    ABSTRACT: Few empirical studies have measured the effects of climate change on tropical biodiversity, and this paucity has contributed to uncertainty in predicting the severity of climate change on tropical organisms. With regards to elevational changes, most studies have either re-sampled historical systematic survey sites or analyzed time series of occurrence data at long-term study sites. Such data sources are unavailable for most tropical mountains, so other methods of detecting elevational changes must be sought. Here we combine data from published checklists, recent fi eld work, peer-reviewed literature, unpublished reports, birdwatchers' trip reports, databases of birdwatchers' observations, audio recordings, and photographs to compare historical (pre-1998) and current (post-2006) bird distributions on Mt. Kinabalu in Sabah, Malaysian Borneo. Records were carefully checked by experts on Bornean birds. More species are now known from Mt. Kinabalu, but historical data provided elevational range estimates for more species than current data because of extensive mountain-wide collections and surveys. Most elevational comparisons for this study had to be limited to the 1450–1900 m elevational band, where most of the recent work has been done. Information was compiled
    Full-text · Article · Jun 2012 · The Raffles bulletin of zoology
  • Thomas E. Martin · John L. Maron
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    ABSTRACT: The contribution of climate change to declining populations of organisms remains a question of outstanding concern1, 2, 3. Much attention to declining populations has focused on how changing climate drives phenological mismatches between animals and their food4, 5, 6. Effects of climate on plant communities may provide an alternative, but particularly powerful, influence on animal populations because plants provide their habitats. Here, we show that abundances of deciduous trees and associated songbirds have declined with decreasing snowfall over 22 years of study in montane Arizona, USA. We experimentally tested the hypothesis that declining snowfall indirectly influences plants and associated birds by allowing greater over-winter herbivory by elk (Cervus canadensis). We excluded elk from one of two paired snowmelt drainages (10 ha per drainage), and replicated this paired experiment across three distant canyons. Over six years, we reversed multi-decade declines in plant and bird populations by experimentally inhibiting heavy winter herbivory associated with declining snowfall. Moreover, predation rates on songbird nests decreased in exclosures, despite higher abundances of nest predators, demonstrating the over-riding importance of habitat quality to avian recruitment. Thus, our results suggest that climate impacts on plant–animal interactions can have forceful ramifying effects on plants, birds, and ecological interactions.
    No preview · Article · Jan 2012 · Nature Climate Change

Publication Stats

4k Citations
449.82 Total Impact Points


  • 2007-2015
    • United States Geological Survey
      Reston, Virginia, United States
    • University of Chicago
      Chicago, Illinois, United States
    • University of California, Riverside
      • Department of Biology
      Riverside, California, United States
    • University of Cambridge
      Cambridge, England, United Kingdom
  • 1996-2015
    • University of Montana
      • • Division of Biological Sciences
      • • Montana Cooperative Wildlife Research Unit
      MSO, Montana, United States
  • 2013
    • The American Ornithologists' Union
      Washington, Washington, D.C., United States
  • 2010
    • University of Wyoming
      • Department of Zoology and Physiology
      Laramie, WY, United States
  • 2008
    • Duke University
      Durham, North Carolina, United States
  • 2003
    • University of Oulu
      • Department of Biology
      Uleoborg, Northern Ostrobothnia, Finland