Summary1. Kirschfeld (1976) suggested that visual acuity is directly proportional to body length across a wide range of animal species. A survey of eye size, visual acuity and body size of birds and mammals that is consistent with Kirschfeld's suggestion is reported. Hypoallometry (scaling factor < 1) for eye size vs body size combines with hyperallometry (scaling factor > 1) for acuity vs eye size to produce roughly linear scaling between acuity and body size. 2. Kirschfeld (1976) also suggested that the distance at which important objects are typically viewed is a linear function of body length. 'Subjective distance' (viewing distance/body length) was therefore thought to be independent of body size across species. However, for prey detection by mammalian and avian predators, it is doubtful that subjective visual distances are size independent because prey size and visual acuity both scale by factors > 0·5 with predator body size; hence, detection distance should scale with size by a factor > 1. Scaling analyses also suggest that subjective visual distances for intraspecific social interactions are size dependent. 3. A positive association between body size and viewing distance has implications for the scaling of coat pattern features. In environments with fractal visual backgrounds (in which perceived sizes of background pattern elements do not change as distance from the background changes), larger animal species should have larger coat patches than smaller species if they are adapted to be cryptic at greater viewing distances than smaller species are.

We take advantage of a fortuitous local extinction and recolonization of white‐lipped peccaries (WLPs) at the Cocha Cashu Biological Station in southeastern Peru to assess the impact of this high‐biomass seed predator on the recruitment of a dominant member of the tree community, the palm Astrocaryum murumuru. WLPs were common at Cocha Cashu in the mid‐1970s. In 1978, the species vanished from the entire region and did not reappear until 1990. To assess the impacts of the presence–absence of WLPs on Astrocaryum recruitment, we conducted transect counts of both the number and spatial distribution of palm seedlings in 1978 (when WLPs were present), in 1990 (after a 12‐yr absence of WLPs), and in 1999 (after 10 yr of recovery). Other factors affecting recruitment, such as climate variability, differences in tree fecundity, and fluctuations of vertebrate and invertebrate seed predators were also examined as alternative hypotheses for any changes in seedling spatial distribution and abundance. In the absence of WLPs, the density of Astrocaryum seedlings increased 1.7‐fold, and the spatial distribution of seedlings with respect to safe sites was significantly altered. After the return of WLPs to the study area, seedling density dropped to its former level, and the spatial distribution of seedlings with respect to safe sites returned to the same pattern found 21 yr earlier in 1978. None of the other factors investigated varied systematically with the census intervals. These results demonstrate that the absence of a single, albeit important, member of a diverse seed predator guild can have a major impact on the demography of a common tree species. We infer that individual seed predators can play central roles in regulating the demography of tropical trees, as envisioned many years ago by Janzen and Connell, and that their extirpation or extinction can have cascading effects in tropical ecosystems. Corresponding Editor: D. R. Strong

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Data were gathered on body weight, body length, relative maximum bite force and relative maximum gape for six sympatric species of neotropical cats (Felidae) to see if constant size ratios occur between adjacent species or if the minimum ratio in a series is greater than expected by chance. Although clearly likely to be correlated, these four parameters were thought to have potential for some independent variation and independent influence on prey capture abilities. None of the four sets of ratios was statistically distinguishable from random when all six species were included in the analysis; however, the ratios for relative maximum gape among just the four largest species were significantly more even and the minimum ratio significantly greater than expected by chance among four species. This constancy occurs because of departures of jaw lengths from what would be expected by the average allometric relationship between this parameter and total body size. Competitive character displacement is a possible explanation for the constant ratios in maximum gape of the larger species, but it is not the only possibility.

Feline leukemia virus (FeLV) was not detected in Florida pumas (Puma concolor coryi) in almost 20 yr of surveillance; however, the finding of two FeLV antigen-positive pumas during the 2002–2003 capture season led to an investigation of FeLV in the population. Between January 1990 and April 2007, the proportion of pumas testing FeLV antibody positive increased, with antibody-positive pumas concentrated in the northern portion of puma range. Five of 131 (4%) pumas sampled between July 2000 and April 2007 were viremic, with all cases clustered in Okaloacoochee Slough (OKS). Clinical signs and clinical pathology at capture were absent or included lymphadenopathy, moderate-to-severe anemia, and lymphopenia. All viremic pumas died; causes of death were septicemia (n=2), intraspecific aggression (n=2), and anemia/dehydration (n=1). Outcome after FeLV exposure in pumas was similar to that in domestic cats, with evidence of regressive, latent, and persistent infections. Management of the epizootic included vaccination, and as of April 2007, 52 free-ranging pumas had received one or more inoculations. Vaccinations were concentrated in OKS and in a band between OKS and the remainder of the puma population. There have been no new cases since July 2004; however, the potential for reintroduction of the virus remains.