Ross MacLeod

Personality in captivity reflects personality in the wild

To investigate the ecological significance of personality, researchers generally measure behavioural traits in captivity. Whether behaviour in captivity is analogous to behaviour in the wild, however, is seldom tested. We compared individual behaviour between captivity and the wild in blue tits, Cyanistes caeruleus. Over two winters, 125 blue tits were briefly brought into captivity to measure exploratory tendency and neophobia using variants of standard personality assays. Each was then released, fitted with a passive integrated transponder. Using an electronic monitoring system, we then recorded individuals’ use of feeders as they foraged in the wild. We used variation in the discovery of new feeders to score 91 birds for exploratory tendency in the wild. At eight permanent feeding stations, 78 birds were assayed for neophobia in the wild. Behavioural variation in the captive personality trials was independent of permanent (e.g. sex) and nonpermanent (e.g. condition or weather) sources of betweenindividual variation at capture. Individual exploratory tendency and neophobia were consistent and repeatable in captivity, and analogous traits were repeatable in the wild; thus all constituted personality traits in the blue tit. Exploratory tendency and neophobia were not correlated with each other, in either the captive or the wild context. Therefore they are independent traits in blue tits, in contrast to many species. Finally, exploratory tendency and neophobia measured in captivity positively predicted the analogous traits measured in the wild. Reflecting differences in the use of feeding opportunities, personality in captivity therefore revealed relevant differences in foraging behaviour between individuals.

Disrupted seasonal biology impacts health, food security and ecosystems

The rhythm of life on earth is shaped by seasonal changes in the environment. Plants and animals show profound annual cycles in physiology, health, morphology, behaviour and demography in response to environmental cues. Seasonal biology impacts ecosystems and agriculture, with consequences for humans and biodiversity. Human populations show robust annual rhythms in health and well-being, and the birth month can have lasting effects that persist throughout life. This review emphasizes the need for a better understanding of seasonal biology against the backdrop of its rapidly progressing disruption through climate change, human lifestyles and other anthropogenic impact. Climate change is modifying annual rhythms to which numerous organisms have adapted, with potential consequences for industries relating to health, ecosystems and food security. Disconcertingly, human lifestyles under artificial conditions of eternal summer provide the most extreme example for disconnect from natural seasons, making humans vulnerable to increased morbidity and mortality. In this review, we introduce scenarios of seasonal disruption, highlight key aspects of seasonal biology and summarize from biomedical, anthropological, veterinary, agricultural and environmental perspectives the recent evidence for seasonal desynchronization between environmental factors and internal rhythms. Because annual rhythms are pervasive across biological systems, they provide a common framework for trans-disciplinary research.

Mass-dependent predation risk and lethal dolphin–porpoise interactions

In small birds, mass-dependent predation risk (MDPR) is known to make the trade-off between avoiding starvation and avoiding predation dependent on individual mass. This occurs because carrying increased fat reserves not only reduces starvation risk but also results in a higher predation risk due to reduced escape flight performance and/or the increased foraging exposure needed to maintain a higher body mass. In principle, the theory of MDPR could also apply to any animal capable of storing energy reserves to reduce starvation and whose escape performance decreases with increasing mass. We used a unique situation along certain parts of coastal Britain, where harbour porpoises (Phocoena phocoena) are pursued and killed but crucially not eaten by bottlenose dolphins (Tursiops truncatus), to investigate whether a MDPR effect can occur in non-avian species. We show that where high levels of dolphin ‘predation’ occur, porpoises carry significantly less energy reserves than would otherwise be expected and this equates to reducing by approximately 37% the length of time that a porpoise could survive without feeding. These results provide the first evidence that a mass-dependent starvation–predation risk trade-off may be a general ecological principle that can apply to widely different animal types rather than, as is currently thought, only to birds.

Mass-dependent predation risk as a mechanism for house sparrow declines?

House sparrow (Passer domesticus) numbers have declined rapidly in both rural and urban habitats across Western Europe over the last 30 years, leading to their inclusion on the UK conservation red list. The decline in farmland has been linked to a reduction in winter survival caused by reduced food supply. This reduction in food supply is associated with agricultural intensification that has led to the loss of seed-rich winter stubble and access to spilt grain. However, urban house sparrows have also declined, suggesting that reduced food supply in farmland is not the sole reason for the decline. Here, we show that changes in house sparrow mass and thus fat reserves are not regulated to minimize starvation risk, as would be expected if limited winter food were the only cause of population decline. Instead, the species appears to be responding to mass-dependent predation risk, with starvation risk and predation risk traded-off such that house sparrows may be particularly vulnerable to environmental change that reduces the predictability of the food supply.

Capture and mass change: perceived predation risk or interrupted foraging?

In animals such as birds that are capable of adjusting energy reserves behaviourally in response to starvation risk and predation risk, mass is a measure of an individuals perception of the risks in its environment. Although it is often necessary to capture and handle animals to allow the scientific study of animal behaviour, little is known about how this affects the individuals perception of the risks in its environment or how this changes subsequent behaviour. In this study we remotely monitored the mass of individual wild great tits, Parus major, for 10 days after capture, handling and release and then used starvation–predation risk trade-off theory to investigate how individuals perceived the risks in their environment. Mass increased significantly after capture and remained higher for 7 days before returning to precapture levels. We conclude that the capture and handling event was perceived as an interruption to foraging induced by an encounter with a predator which heightened starvation risk. Although this forced interruption to foraging was a relatively small proportion of available foraging time (

A study of the parrot trade in Peru and the potential importance of internal trade for threatened species

Summary During a period of 12 months in 2007 and 2008, a study of the parrot trade within Peru was carried out. In this study, 20 main wildlife markets were visited in eight cities in order to estimate the number of parrot species and individuals traded legally and illegally within a year. The study also gathered extra information from vendors and customers through informal interviews about the trade process. Additionally we contracted one person in two markets between February and May 2008 to monitor how many species and individuals entered the trade. During the study, four threatened species (the ‘Endangered’ Gray-cheeked Parakeet Brotogeris pyrrhoptera, the ‘Vulnerable’ Military Macaw Ara militaris, the ‘Vulnerable’ Yellow-faced Parrotlet Forpus xanthops and the ‘Near Threatened’ Red-masked Parakeet Aratinga erythrogenys) and one additional species listed in CITES Appendix 1 (Scarlet Macaw Ara macao) were found being traded. Thirty-four species were recorded in total, 33 of which are native to Peru (representing 63 %o f the52 known Peruvian parrot species) and one of which (Monk Parakeet Myiopsitta monachus) is native to Bolivia and Argentina. Our results show that even for the seven species which can be legally traded in Peru, the number of individuals being traded can greatly exceed the numbers that can officially be traded legally. We directly counted 4,722 parrots for sale and using a measured detection rate of 3% we estimate a total market size in the cities surveyed of between 80,000 and 90,000 individuals. As our surveys sampled only 8 out of Peru’s 24 departmental capitals and there are also other large cities, these numbers are likely to represent only a part of the total trade in Peru. To the best of our knowledge this is one of the first detailed studies of the internal trade in a source country for the international parrot trade. Our results suggest that such internal trade is likely to be a significant conservation issue that has previously been largely overlooked.

How climate change might influence the starvation-predation risk trade-off response

Climate change within the UK will affect winter starvation risk because higher temperatures reduce energy budgets and are likely to increase the quality of the foraging environment. Mass regulation in birds is a consequence of the starvation–predation risk trade-off: decreasing starvation risk because of climate change should decrease mass, but this will be countered by the effects of predation risk, because high predation risk has a negative effect on mass when foraging conditions are poor and a positive effect on mass when foraging conditions are good. We tested whether mass regulation in great tits (Parus major) across the UK was related to temporal changes in starvation risk (winter temperature 1995–2005) and spatial changes in predation risk (sparrowhawk Accipiter nisus abundance). As predicted, great tits carried less mass during later, warmer, winters, demonstrating that starvation risk overall has decreased. Also, the effects of predation risk interacted with the effects of temperature (as an index of foraging conditions), so that in colder winters higher sparrowhawk abundance led to lower mass, whereas in warmer, later, winters higher sparrowhawk abundance led to higher mass. Mass regulation in a small bird species may therefore provide an index of how environmental change is affecting the foraging environment.

Densities and habitat preferences of Andean cloud-forest birds in pristine and degraded habitats in north-eastern Ecuador

W. CRESSWELL, M. HUGHES, R. MELLANBY, S. BRIGHT, P. CATRY,J. CHAVES, J. FREILE, A. GABELA, H. MARTINEAU, R. MACLEOD,F. MCPHIE, N. ANDERSON, S. HOLT, S. BARABAS, C. CHAPELandT. SANCHEZSummaryThe montane cloud-forest of ths north-centrae l Ande ansd the montan e grasslan andtransitional elfin fores of tht centrae l Andean paramo contai a highn diversit of biry dspecies including several restricted rang ande uncommo n species. Littl ies known of howdensities o Andeaf n cloud-fores ar affecteet specie bdy habitas t degradation. Birddensities within pristine and degraded habitat ats the Guandera Biological Reserve, Carchiprovince, Ecuador were recorded ove a 10-weer k period. Densities were calculate ford 48species; where densities coul bed compared, 69% of species occurre adt a higher densityin pristine habitats. Pristin hae foresd th higheste t species richness 7 wit2 specieh s andparamo containe 4d4 species. In total, 26% of pristine forest species were onl iy founndpristine forest, 39 o%f paramo species onl iny paramo , 13% of farmland species i onln yfarmland and there were no exclusively secondary scrub species; 47 o%f species found inpristine forest an,d 50 foun% d in paramo were foun in botdh secondary an scrud bfarmland. Restricted range specie at Guander s recordea included th Carujiculatede dCaracara Phalcobenus carunculatus, Black-thighed Puffleg Eriocnemis derbyi,Chestnut-bellied Coting Doliornisa remseni, Crescent-faced Antpitt Grallariculaa lineifrons,Masked Mountain-tanage anr Black-backed Buthraupisd wetmorei Bush-tanagerUrothraupis stolzmanni. Three further species that occurre at Guanderd a of relatively localoccurrence wer the Grey-breastee d Mountain Toucan Andigena hypoglauca,Golden-breasted Puffleg Eriocnemis and Mountai mosqueran Avocetbil Opisthoproraleuryptera. Of these nine specie ast least five used degraded habitats, while three occurredonly in pristine treeline habitats.IntroductionThe Andes of South America contain several areas of bird endemism (Collar etal. 1994, Stattersfield et al. 1998). Two of these endemic bird areas (EBAs) are themontane cloud-forests of the north-central Andes and the montane grasslandand transitional elfin forest of the central Andean paramo (Wege and Long 1995,Stattersfield et al .1998). The north-central Andes contain at least eight restrictedrange species and the central Andean paramo at least 10 (Wege and Long 1995,Stattersfield et al. 1998). These endemic bird areas have been subject to wide-spread and severe deforestation in this and recent centuries. The transitional

Why does diurnal mass change not appear to affect the flight performance of alarmed birds

To survive, animals need to trade-off gaining energy with the avoidance of predation. In small birds, this trade-off is thought to be mass dependent because increased mass is expected to reduce maximum flight performance during escape from predators. For large mass changes, flight performance during escape follows the inverse relation predicted by Newtonian physics but apparently not for small mass changes. I investigated three possible explanations for this apparent breach of Newtonian physics. In a study of free-living great tits, Parus major, I found no significant change in flight performance in relation to diurnal mass change. First, the novel design of the experiment rules out various potential confounding factors common to previous experiments as an explanation. Second, I used the work–energy theorem from physics to show that birds did the same amount of work in morning and evening escape flights. This indicates that the birds were maximizing their flight performance and rules out physiological compensation to increased mass as an explanation. Third, by calculating the evening flight performances predicted by Newtonian physics for each individual in my experiment, I show that the level of diurnal mass change present in both this and previous studies could not be expected to produce a statistically significant change in flight performance. The results suggest that an effect of diurnal mass gain on alarmed flight speed would be undetectable with the sample sizes used so far.

Predicting population-level risk effects of predation from the responses of individuals

Fear of predation produces large effects on prey population dynamics through indirect risk effects that can cause even greater impacts than direct predation mortality. As yet, there is no general theoretical framework for predicting when and how these population risk effects will arise in specific prey populations, meaning that there is often little consideration given to the key role predator risk effects can play in understanding conservation and wildlife management challenges. Here, we propose that population predator risk effects can be predicted through an extension of individual risk trade-off theory and show for the first time that this is the case in a wild vertebrate system. Specifically, we demonstrate that the timing (in specific months of the year), occurrence (at low food availability), cause (reduction in individual energy reserves), and type (starvation mortality) of a population-level predator risk effect can be successfully predicted from individual responses using a widely applicable theoretical framework (individual-based risk trade-off theory). Our results suggest that individual-based risk trade-off frameworks could allow a wide range of population-level predator risk effects to be predicted from existing ecological theory, which would enable risk effects to be more routinely integrated into consideration of population processes and in applied situations such as conservation.