Feeding behavior and crop damage caused by capybaras (Hydrochoerus hydrochaeris) in an agricultural landscape

Crop damage by vertebrates in Latin America: current knowledge and potential future management directions

Background

Crop farming contributes to one of the most extensive land use activities in the world, and cropland areas continue to rise. Many vertebrate species feed on crops, which has caused an increase in human-wildlife conflicts in croplands. Crop-feeding damages the economy of local communities and causes retaliation against the responsible vertebrates in several forms, including lethal practices such as hunting and poisoning. Lethal control may cause the local extirpation of some species, affecting ecological processes and patterns. Therefore, it is necessary to find non-lethal alternatives that can protect both local economies and wildlife. Research has been conducted in Africa and Asia, focusing on elephants and primates, and the effectiveness of some non-lethal alternatives, such as chili-based repellents and beehives, is being investigated. However, there has been very little research on this topic in Central and South America. The goal of this review is to assess the current knowledge on crop damage by vertebrates in Central and South America and indicate future research directions.

Survey methodology

We reviewed the available scientific literature reporting crop damage by vertebrates in Central and South America, and the Caribbean, published between 1980 and 2020, through systematic searches on Web of Science, Scopus, and Google Scholar. We analyzed the temporal and geographical distributions of the studies, the crops and vertebrate species these studies considered, the crop protection techniques used, and their effectiveness.

Results

We retrieved only 113 studies on crop damage by vertebrates in Latin America, but there was an increasing trend in the number of studies published over time. Most of the studies were conducted in Brazil, Argentina, Mexico, and Costa Rica. Four orders of mammals (Rodentia, Carnivora, Artiodactyla, and Primates) and four orders of birds (Passeriformes, Columbiformes, Psittaciformes, and Anseriformes) were the most common groups of crop-feeding vertebrates. The most prominent crop was corn, which was featured in 49% of the studies. Other notable crops include rice, sorghum, and sugarcane. The most reported method for protecting crops was lethal control through hunting or poisoning. Non-lethal techniques were found to be less prevalent. Less than half of the studies that mentioned the use of protection techniques indicated their effectiveness, and only 10 studies evaluated it by performing scientific experiments and reporting their results.

Conclusions

Central and South America is still underrepresented in research on vertebrate crop-feeding. There is a need for experimentation-based robust research to find crop protection techniques that minimize harm to vertebrates while effectively reducing damage to crops. While this is being studied, habitat loss and fragmentation need to be halted to prevent the native vertebrates from turning to crops for food.

Human-modified landscapes alter home range and movement patterns of capybaras

The expansion of human activity forces species to co-exist with people in human-modified landscapes (HMLs). However, living in HMLs demands behavioral adaptations, and the proximity between wildlife and people heightens human–wildlife conflicts. Capybara (Hydrochoerus hydrochaeris) is a thriving rodent species in HMLs in Brazil and as such, is involved in human–wildlife conflicts, such as vehicle collisions and transmission of Brazilian spotted fever (BSF). Despite their public importance, the effects of HMLs on capybara movement behavior have never been investigated. Our study aimed to investigate changes in home range, ranging pattern, and activity, for capybaras in six HMLs and two natural landscapes (NLs) by monitoring capybaras with GPS collars. We found home ranges 2.43 times greater in NLs than in HMLs and differences in ranging pattern in HMLs. Capybaras tended to be more nocturnal and move shorter distances across HMLs than NLs. Our results confirm the impacts of the HMLs altering capybara movement. The aggregation of capybaras in very small home ranges might imply on greater risks of tick infestations. In addition, capybara–vehicle collision may be increased during capybaras’ nocturnal activity. Therefore, we recommend that transportation agencies avoid the construction of transportation infrastructures (roads, railways, airstrips) in capybaras’ home ranges, which should be of restricted access to people in BSF endemic areas.

Field-testing a single-dose immunocontraceptive in free-ranging male capybara (Hydrochoerus hydrochaeris): Evaluation of effects on reproductive physiology, secondary sexual characteristics, and agonistic behavior

Controlling wildlife populations to mitigate human-wildlife conflicts and the spread of zoonotic diseases is an ever-growing necessity. The objective of this study was to evaluate a single-dose anti-gonadotropin-releasing hormone vaccine (GonaCon, USDA/NWRC, Fort Collins, CO, USA) as a non-lethal alternative for population control in free-ranging, synanthropic male capybara. In addition to infertility efficacy of this treatment, potential effects on the alpha male's secondary sexual characteristics and agonist behavior need to be assessed because any alterations in these factors could lead to population management failure. The treatment group (n = 3) received 1 mL of the anti-GnRH vaccine, intramuscularly, and the control group (n = 2) a 1 mL sham vaccine. Reproductive behavior and social group dynamics were monitored for 30 days prior to inoculation (June 2017) with continuous observations occurring during the study period. Antifertility effects were assessed by conducting exams of testicular morphology, semen characteristics, and histological analysis (after 270 days via hemi-gonadectomy). Compared to the control group, the testicles of the treated males had severe atrophy (P <  0.05), oligozoospermia and greater numbers of sperm cells in a static developmental phase. Courtship and agonistic alpha male behavior were not altered, and the group's social integrity was maintained. Results indicate there was 100% infertility in capybara males, observed throughout the study period of 18 months, and equally important, the male's alpha characteristics were not affected by the treatment, which is imperative for successful capybara population control efforts.

Omnivorous Behaviour of the Agouti (Dasyprocta leporina): A Neotropical Rodent with the Potential for Domestication

The agouti is a Neotropical rodent which is mainly utilized for its meat in rural communities. Recently, captive rearing of these animals by wildlife farmers have increased in the Neotropics. This short communication consists of observation of feeding behaviour of captive reared agoutis at the University of the West Indies Field Station in Trinidad and Tobago. This is the first time in Trinidad and Tobago that meat consumption and the omnivorous behaviour of the agouti have been documented in the literature. The consumption of chicken (Gallus domesticus) eggs, dead chickens, and a brown dove (Zenaida macroura) by captive reared agoutis was noted. This document described the omnivorous behaviour of the agouti which is primarily considered a frugivorous animal. Similar studies in South America have shown that wild and captive reared agoutis consumed animal matter. Further work must be done on the dietary needs and nutrient requirements of the agouti at different physiological states.

Nutrition of Six Selected Neo-Tropical Mammals in Trinidad and Tobago with the Potential for Domestication

This review highlights the available literature on the nutrition of six neo-tropical animals with the potential for domestication—the agouti (Dasyprocta leporina/D. aguti), lappe (Agouti paca), capybara (Hydrochoerus hydrochaeris), manicou/opossum (Didelphis marsupialis insularis), collared peccary (Peccary tajucu) and the red brokcet deer (Mazama americana). Over 100 references were used, spanning over 100 years. The earliest being 1915 and the most recent being 2018. The references used in this review were synthesized to give a detailed look of the dentition, anatomy of the gastrointestinal tract and type of feed these animals consume. Nutritional requirements of the animals are required to understand what is needed for growth, maintenance and reproduction of each physiological stage. The agouti (D. leporina/D. aguti) was observed to be a monogastric mammal that fed primarily on fruits, seeds, animal matter and practiced caecotrophy. The lappe/paca (C. paca/A. paca) was described as a strict herbivore and a frugivore which practiced caecotrophy, with a diet that varied throughout the year, according to food availability. The capybara (H. hydrochaeris) was found to be the largest known rodent and was described as a semiaquatic hindgut fermenter that practiced caecotrophy. The manicou/opossum (D. marsupialis insularis) was found to be an omnivore with a simple stomach. The collared peccary (T. tajacu) was found to be frugivorous. Their unique stomach enabled them to consume a wide variety of feedstuff, allowing them to be found in a wide range of habitats. The red brocket deer (M. americana), a ruminant, was described as a browser that consumed mainly fruits and seeds and they frequented mineral lick. Knowledge of what they consume in the wild is important, so that we know what to feed in captivity. There is also the need to evaluate captive diets while trying to domesticate these mammals and develop nutrient requirement tables for these neo-tropical animals. Finally, an understanding of the dentition and gastrointestinal tract is important to increase efficiency (nutritional and cost). These six neo-tropical mammals were chosen due to their prevalence as game species in Trinidad and Tobago.

CAPIVARAS (Hydrochoerus hydrochaeris) E A PRESENÇA DO CARRAPATO (Amblyomma sculptum) NO CAMPUS DA UFSCAR-ARARAS, SÃO PAULO

Resumo Capivaras são territoriais e vivem em grupos sociais, ocorrendo comumente em áreas antropizadas. Em algumas regiões do Brasil, estes animais apresentam infestação por carrapatos do gênero Amblyomma, que por sua vez são considerados como principal vetor biológico e reservatório natural da bactéria Rickettsia rickettsii, agente causador da Febre Maculosa Brasileira. Na UFSCar campus Araras, a interação entre capivaras, carrapatos e comunidade acadêmica é frequente, ocorrendo principalmente durante a estação seca. Este estudo teve como objetivo realizar um censo populacional das capivaras que ocupam o campus, identificando sua área de uso e se estes roedores se encontravam infestados por carrapatos. Realizou-se observação direta das capivaras, captura-marcação e recaptura com uso de um brete, e também coleta dos carrapatos nas capivaras e no ambiente. Registrou-se um total de 56 capivaras, com densidade de 1,50 ind./ha. Foram capturados 24 animais, sendo 25% machos e 75% fêmeas, dos quais 25% eram adultos, 45,8% jovens e 29,2% filhotes. A espécie de carrapato amplamente encontrada infestando tanto os animais como o ambiente foi A. sculptum. Conclui-se que o grupo de capivaras apresentou um número elevado de indivíduos por causa da abundância de recursos e ausência de predadores, e também com grande infestação por carrapatos.

Satellite Hyperspectral Imagery to Support Tick-Borne Infectious Diseases Surveillance

This study proposed the use of satellite hyperspectral imagery to support tick-borne infectious diseases surveillance based on monitoring the variation in amplifier hosts food sources. To verify this strategy, we used the data of the human rickettsiosis occurrences in southeastern Brazil, region in which the emergence of this disease is associated with the rising capybara population. Spatio-temporal analysis based on Monte Carlo simulations was used to identify risk areas of human rickettsiosis and hyperspectral moderate-resolution imagery was used to identify the increment and expansion of sugarcane crops, main food source of capybaras. In general, a pixel abundance associated with increment of sugarcane crops was detected in risk areas of human rickettsiosis. Thus, the hypothesis that there is a spatio-temporal relationship between the occurrence of human rickettsiosis and the sugarcane crops increment was verified. Therefore, due to the difficulty of monitoring locally the distribution of infectious agents, vectors and animal host's, satellite hyperspectral imagery can be used as a complementary tool for the surveillance of tick-borne infectious diseases and potentially of other vector-borne diseases.