The tiger Panthera tigris is an apex predator categorized as Endangered on the IUCN Red List. The availability of sufficient prey is a key requirement for its survival. The tiger diet landscape refers to a dynamic ecological picture of the diverse prey species consumed by tigers in a specific region, reflecting the complex relationships between tiger populations and their prey. It can provide information on the tiger’s preferred prey as well as the conservation status of prey species across boundaries. To draw up a road map for the conservation and management of tigers across the Indian subcontinent, where the Bengal tiger Panthera tigris tigris occurs, we identified which prey species make up the majority of the tiger’s diet and answered questions relating to prey density, distribution and conservation status. We reviewed 48 studies published over 30 years (1992–2022) on tiger diet and prey availability. We recorded c. 30 mammalian prey species, with chital Axis axis, sambar Rusa unicolor, wild boar Sus scrofa, Tarai gray langur Semnopithecus hector, northern red muntjac Muntiacus vaginalis and domestic livestock contributing c. 90% of the total relative biomass consumed. Nearly half of the prey species are of conservation concern (categorized as Near-Threatened, Vulnerable or Endangered on the IUCN Red List), and 11 prey species are listed on CITES Appendix I. As part of a sustainable tiger conservation road map, we suggest that the tiger’s major prey species should be incorporated into government protection schemes.

The leopard Panthera pardus is in range-wide decline, and many populations are highly threatened. Prey depletion is a major cause of global carnivore declines, but the response of leopard survival and density to this threat is unclear: by reducing the density of a dominant competitor (the lion Panthera leo) prey depletion could create both costs and benefits for subordinate competitors. We used capture–recapture models fitted to data from a 7-year camera-trap study in Kafue National Park, Zambia, to obtain baseline estimates of leopard population density and sex-specific apparent survival rates. Kafue is affected by prey depletion, and densities of large herbivores preferred by lions have declined more than the densities of smaller herbivores preferred by leopards. Lion density is consequently low. Estimates of leopard density were comparable to ecosystems with more intensive protection and favourable prey densities. However, our study site is located in an area with good ecological conditions and high levels of protection relative to other portions of the ecosystem, so extrapolating our estimates across the Park or into adjacent Game Management Areas would not be valid. Our results show that leopard density and survival within north-central Kafue remain good despite prey depletion, perhaps because (1) prey depletion has had weaker effects on preferred leopard prey compared to larger prey preferred by lions, and (2) the density of dominant competitors is consequently low. Our results show that the effects of prey depletion can be more complex than uniform decline of all large carnivore species, and warrant further investigation.

Rajaji National Park, which forms the north-western limit of the range of the tiger Panthera tigris in India, is bisected into western and eastern sectors by development activities along the banks of the river Ganga. Following a voluntary pastoral Gujjar resettlement programme initiated in the Park by the Uttarakhand Forest Department, we assessed the status of the tiger and its prey. We used sign surveys for tigers, leopards Panthera pardus and their prey, estimated prey densities using line transects and distance sampling, and estimated the density of tigers using photographic capture-recapture analysis. Our results indicate that the use of the area by tigers differed significantly between the two sectors of the Park, with pug mark encounter rates per 250 m segment from sign surveys of 0.07 ± SE 0.04 in the west and 1.6 ± SE 0.3 in the east. Although the high estimated prey densities (> 80 km-2) in the Park have the potential to support high densities of tigers, we photo-captured only one tigress in the western sector and five adult tigers and two cubs in the east (the latter with a mean density of 5.12 ± SE 0.7 per 100 km2). Whereas recovery of the tiger population in the eastern sector following the resettlement of Gujjars is evident, the lack of connectivity to source populations (Corbett Tiger Reserve and eastern Rajaji National Park) and increased anthropogenic pressures appear to have inhibited the recovery of tiger populations in the western sector. Restoration, therefore, of the Chilla-Motichur corridor to facilitate the dispersal of tigers from the eastern to the western sector of the Park is of critical importance.

The effects and persistence of oviposition-deterring semiochemical cues from conspecific and heterospecific larval tracks on the oviposition rate of Aphidecta obliterata (Linnaeus) females were investigated. In addition, the effects of varying aphid prey density were considered and also whether any resulting response originated from differential nutritional status of females and/or due to aphid odour stimuli. The existence of oviposition responses to conspecific egg chemicals was also considered. Gravid A. obliterata females were deterred from oviposition by conspecific larval tracks and the effect was density dependent. Females actively avoided searching in these contaminated areas. Tracks induced a significant effect on oviposition for up to three days. Heterospecific tracks of the coccinellid Adalia bipunctata (Fabricius) or the chrysopid Chrysoperla carnea (Stephens) did not induce any oviposition response in A. obliterata females. Increasing aphid density induced increased oviposition rate in A. obliterata females. Nutritional status of females was an important factor in the relationship between aphid density and oviposition rate, but aphid associated cues (odours) were not. There was an inhibitory effect of extracts of conspecific egg-surface chemicals on oviposition by A. obliterata females. In the field, cannibalism, competition and limited food availability represent the major threats to egg and larval survival. Patch quality assessment mechanisms enable females to lay eggs at sites where offspring survival is maximized. Oviposition-deterring semiochemicals tend to promote more even distribution of predators over prey patches.

Variation in size of home range is among the most important parameters required for effective conservation and management of a species. However, the fact that home ranges can vary widely within a species makes data transfer between study areas difficult. Home ranges of Eurasian lynx Lynx lynx vary by a factor of 10 between different study areas in Europe. This study aims to try and explain this variation in terms of readily available indices of prey density and environmental productivity. On an individual scale we related the sizes of 52 home ranges, derived from 23 (9:14 male:female) individual resident lynx obtained from south-eastern Norway, with an index of density of roe deer Capreolus capreolus. This index was obtained from the density of harvested roe deer within the municipalities covered by the lynx home ranges. We found a significant negative relationship between harvest density and home-range size for both sexes. On a European level we related the sizes of 111 lynx (48:63 male: female) from 10 study sites to estimates derived from remote sensing of environmental productivity and seasonality. A multiple linear regression model indicated that productivity of the study site had a clear negative relationship with home-range size. At both scales, sex emerged as a significant explanatory variable with males having larger home ranges than females. In addition, the size of male home-ranges increased faster with decreasing prey density than for females. These analyses support widely held predictions that variation in home-range size is due to variation in prey density.

The functional response of fourth instars, adult males and females of the sevenspotted lady beetle, Coccinella septempunctata Linnaeus (Coleoptera: Coccinellidae), was studied at different densities of aphid, Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae). The maximum prey consumption was recorded for fourth instars at the highest prey density (800) and the minimum for the male lady beetle at the lowest prey density (25). The prey consumption by the predatory stages of the lady beetle was directly and the percent prey consumption inversely proportional to prey density. Prey handling time decreased with increasing prey density. Regression analysis showed a linear relationship between the log number of prey exposed for predation and prey consumed. The predatory efficiency of the predator stages was directly proportional to prey density, indicating a Holling Type II functional response.

When prey availability depends on water depth, a diver should choose an optimal depth for foraging. A model that predicts the optimal foraging depth for a diver is presented in this paper. General predictions derived from the model are: (1) optimal foraging depth is always shallower than the depth at which prey density is the highest, even if the depth of the highest prey density is within easy reach; (2) a larger diver should make deeper and longer dives and stay longer on the surface than smaller divers for optimal foraging; (3) foraging efficiency of larger divers is not always greater than smaller divers, although the larger divers forage at the depth of higher prey density. These predictions, derived from the model, are consistent with the comparative studies of diving behaviour in marine birds.

The functional response in terms of prey consumption and numerical response in terms of number of eggs laid by individual female adult predators of Coccinella transversalis Fab. and Cheilomenes (Menochilus) sexmaculatus Fab. (Coccnellidae: Coleoptera) at varied prey (Aphis gossypii Glover) (Aphididae: Homoptera) densities were investigated under laboratory conditions. The feeding rate by individual predators increased at increased prey densities, with both the coccinellids showing the Type II functional response. One hundred percent prey consumption was observed up to an initial prey density of 50 and 20 for Co. transversalis and Ch: sexmaculatus respectively. The fecundity of Co. transversalis increased at higher prey densities, but that of Ch. sexmaculatus remained unchanged.

The density responsiveness of larvae and adults of Cheilomenes lunata (Fabricius) preying on Aphis craccivora Koch was investigated under laboratory conditions where temperature and relative humidity were uncontrolled and fluctuated between 24–30°C and 43–90% respectively. The feeding rates of C. lunata were positively correlated with the population density of prey. The number of prey consumed daily by each predator stage tested, increased more steeply at lower, than at higher prey densities, exhibiting thus the Type II functional response. Fecundity of C. lunata females also increased to a plateau with increasing prey density.