Red Squirrels (Sciurus vulgaris) Respond to Alarm Calls of Eurasian Jays (Garrulus glandarius)

Recognition of heterospecific (interspecific) alarm calls has been demonstrated in birds and mammals, but bird–mammal interactions have rarely been studied. Here, I tested the hypothesis that red squirrels (Sciurus vulgaris) are able to recognize alarm calls of a sympatric bird species, the Eurasian jay (Garrulus glandarius), and respond adequately with anti‐predator behaviour. Both animals are preyed upon by the same predators. To test whether squirrels would react to heterospecific alarm calls, I recorded squirrels behaviour during playbacks of jay alarm calls, control playbacks (territorial songs of sympatric songbirds) and during silence. Differences between the control treatment (songbirds) and silence were not significant. Seven of the 13 squirrels responded with escape after broadcasting alarm calls of jays. Further, squirrels spent less time in the patch, expressed a higher vigilance, and showed more rapid head and body movements. These results suggest that squirrels recognize heterospecific alarm vocalizations of jays and discriminate them from equally loud non‐threatening sounds.     

Seasonal patterns of food storing in the Jay Garrulus glandarius

This study investigated seasonal patterns in food consumption and food storage in six captive Jays Garrulus glandarius. In the first experiment, seasonal changes in food-storing intensity were tested by presenting acorns (oak seeds, Quercus spp.) in spring, summer and autumn. There were no significant differences between the seasons in the amount of food eaten. However, significantly more food was taken and stored in the autumn than in the spring and summer months. In the spring and summer, the acorns were stored between the doorframes, on the ledges of the aviaries and under the bark of branches. In the autumn, Jays also began to hoard underneath the plastic sheeting covering the hard-board flooring by ripping the polythene to create a hidden cache site. The length of time over which the stored food was left before retrieval increased from summer to autumn. Food storing also occurred in spring and summer but was short term. The second experiment tested whether or not there were seasonal changes in food preference by presenting birds with acorns, peanuts and mealworms in the summer and autumn. More peanuts were eaten, taken and stored in the autumn than in the summer, and, as in the first experiment, significantly more acorns were taken and stored in the autumn. In the autumn, only a few mealworms were eaten before the birds stored acorns and peanuts, whereas in the summer, birds tended to eat most of the mealworms before they began to store. As in the first experiment, items tended to be buried in the ground in the autumn and left for longer periods before retrieval. These results are discussed in relation to the demand that each food type places on the Jay's time.     

Responses of breeding Reed Warblers Acrocephalus scirpaceus to mounts of Sparrowhawk Accipiter nisus, Cuckoo Cuculus canorus and Jay Garrulus glandarius

Mounts of a Cuckoo Cuculus canorus , a Sparrowhawk Accipiter nisus and a Jay Garrulus glandarius were presented at nests of Reed Warblers Acrocephalus scirpaceus at all breeding stages. Response strength could best be classified according to approach distance (to the mount) and vocalizations used. Warblers reacted much more aggressively to a mount on the nest than to one 3 m adjacent; they approached much more closely, were less likely to sing but often gave a frenzied-sounding rasp (which was never given to an adjacent mount). Reaction was more aggressive to a Cuckoo, which was often attacked, than to a Sparrowhawk, of which they were wary; response to a Jay was intermediate. Reaction was more aggressive after the clutch had been completed than before. After the brood had fledged, parents still responded strongly to the Jay and Sparrowhawk, but responded to the Cuckoo only briefly before ignoring it. These results are consistent with the Reproductive Value-Stimulus Value hypothesis. They also demonstrate that Reed Warblers can tell Cuckoos from Sparrowhawks, as can many non-host species. The close resemblance of these two species is often suggested to be mimicry of the Sparrowhawk by the Cuckoo but, if this is so, it is not successful. Alternatively, the similarity could be mimicry to reduce predation on the Cuckoos themselves, a chance resemblance, or due to similar selective forces acting on both species, as each would presumably benefit from reduced conspicuousness.     

Food Storage in Gray Jays: Source Type and Cache Dispersion

Animals that store food items in scattered sites must decide how to distribute their caches in space. Our theoretical approach is based on the assumption that such animals disperse their caches in a manner that maximizes the long-term rate of storage of recoverable (surviving) food items in the habitat. We investigate the cache-spacing behavior of theoretical scatter hoarders that encounter food sources differing in the energetic content of the items they contain. We then describe a field experiment in which gray jays (Perisoreus canadensis) were presented with both small- and large-item food sources. The jays compensated for source type by spacing larger-item caches more widely, a compensation that would tend to yield a high rate of storage of recoverable food energy over the long term and throughout the territory. Previous models do not adequately account for the observed patterns of cache dispersion.     

Eurasian jays (Garrulus glandarius) overcome their current desires to anticipate two distinct future needs and plan for them appropriately

Western scrub-jays (Aphelocoma californica) have been shown to overcome present satiety to cache food they will desire in the future. Here, we show that another corvid, the Eurasian jay (Garrulus glandarius), can distinguish between two distinct future desires and plan for each appropriately, despite experiencing a conflicting current motivation. We argue that these data address the criticisms of previous work, and suggest a way in which associative learning processes and future-oriented cognition may combine to allow prospective behaviour.     

The Food of Nestling Jays and Magpies

Half of the 4,000 Grey Plovers which reach the Wash in late summer remain there to moult; more than a quarter are already in arrested wing moult, having begun elsewhere. The authors discuss this condition and also the birds' movements in the light of ringing recoveries.     

Vocal mimicry of hosts by Great Spotted Cuckoo Clamator glandarius: further evidence

Great Spotted Cuckoo nestlings were shown, after some days in the nest, to have begging calls that differed depending on whether they were being reared by Magpies or Carrion Crows. They also produced calls of a pitch and repetition rate that implied a high level of hunger.     

Recaching Decisions of Florida Scrub‐Jays are Sensitive to Ecological Conditions

Food caching animals depend on their caches at times of low food availability. Because stored food is susceptible to being stolen or degraded, many species employ cache protection strategies such as ceasing caching in the presence of others or avoiding storing perishable items for long periods. Several species frequently recover their caches and recache, which may reduce pilferage or degradation of cached items. We studied the food handling decisions of Florida scrub‐jays (Aphelocoma coerulescens) after cache recovery to determine the roles that social and ecological environments play in post‐recovery decisions. Instead of reducing recaching in the presence of others, recovering jays flew away from the recovery site, allowing them to eat or recache a recovered item regardless of the social context. Microhabitat type and soil moisture of the recovery sites had a significant influence on whether recoveries were eaten or recached; most items that were recached had been recovered from bare sand sites or sites with low soil moisture. Taken together, our results suggest that food store management of Florida scrub‐jays are unaffected by the social context, but are strongly affected by the habitat conditions that influence the quality of caches.     

Production of nitric oxide by ammonium-oxidizing bacteria colonizing building stones

Abstract Stone samples from corroding historical buildings in Germany released NO in significant amounts during oxidation of ammonium to nitrate. Nitrite intermediately accumulated to low concentrations. Nitrification and NO release were detectable only in stones with neutral pH. Addition of nitrapyrin inhibited both ammonium oxidation and NO production. NO was produced in stone samples containing Nitrosomonas or Nitrosovibrio , but was not produced in samples containing only Nitrobacter . Addition of nitrite stimulated NO production in autoclaved stone samples significantly only if dried to < 2% water content, or in acidic stone samples. In moist neutral stones, NO production was only slightly stimulated by nitrite giving less than about 8% of the NO production observed under nitrifying conditions. Most of the NO production by corroding building stones was apparently due to ammonium-oxidizing nitrifiers.     

Dynamics and Phylogenetic Implications of MtDNA Control Region Sequences in New World Jays (Aves: Corvidae)

To study the evolution of mtDNA and the intergeneric relationships of New World Jays (Aves: Corvidae), we sequenced the entire mitochondrial DNA control region (CR) from 21 species representing all genera of New World jays, an Old World jay, crows, and a magpie. Using maximum likelihood methods, we found that both the transition/transversion ratio (κ) and among site rate variation (α) were higher in flanking domains I and II than in the conserved central domain and that the frequency of indels was highest in domain II. Estimates of κ and α were much more influenced by the density of taxon sampling than by alternative optimal tree topologies. We implemented a successive approximation method incorporating these parameters into phylogenetic analysis. In addition we compared our study in detail to a previous study using cytochrome b and morphology to examine the effect of taxon sampling, evolutionary rates of genes, and combined data on tree resolution. We found that the particular weighting scheme used had no effect on tree topology and little effect on tree robustness. Taxon sampling had a significant effect on tree robustness but little effect on the topology of the best tree. The CR data set differed nonsignificantly from the tree derived from the cytochrome b/morphological data set primarily in the placement of the genus Gymnorhinus, which is near the base of the CR tree. However, contrary to conventional taxonomy, the CR data set suggested that blue and black jays (Cyanocorax sensu lato) might be paraphyletic and that the brown jay Psilorhinus (=Cyanocorax) morio is the sister group to magpie jays (Calocitta), a phylogenetic hypothesis that is likely as parsimonious with regard to nonmolecular characters as monophyly of Cyanocorax. The CR tree also suggests that the common ancestor of NWJs was likely a cooperative breeder. Consistent with recent systematic theory, our data suggest that DNA sequences with high substitution rates such as the CR may nonetheless be useful in reconstructing relatively deep phylogenetic nodes in avian groups. Received: 10 November 1999 / Accepted: 16 March 2000     

Storage and survival of bacteria by ultra-freeze

L yon , G.D., S mith , K.J. & H eilbronn , J. 1986. The calcium requirement of polygalacturonic acid lyases produced by Erwinia spp. Letters in Applied Microbiology , 2 , 127–129.
The optimum calcium concentration for polygalacturonic acid lyase (PL) activity in culture filtrates of Erwinia spp. varied between isolates but was generally between 0.2 and 1 mmol/l. Isozymes of PL have different calcium optima at approximately 0.2, 1, 1.3, 1.6 and 1.8 mmol/l Ca²⁺.     

Migration of gall stones.

The factors influencing the migration of gall stones are ill understood. Altogether 331 patients undergoing cholecystectomy were studied prospectively. The diameters of the cystic and common bile ducts and of stones in the gall bladder and bile ducts were measured. Increasing pressure was applied to the freshly excised gall bladder in an attempt to evacuate stones through the cystic duct. Stones passed in 33 (60.0%) of patients with choledocholithiasis, 45 (67.2%) of patients with pancreatitis, and 7 (3.2%) of patients without either pancreatitis or choledocholithiasis. Stones migrated in 6 (3.0%) who had a normal cystic duct diameter (less than or equal to 4 mm) and in 46 (32.5%) with a duct over 4 mm diameter. Common bile duct stones were often larger than the diameter of the cystic duct and when reintroduced into the gall bladder would not migrate. The passage of debris (less than or equal to 1 mm) through the cystic duct bore no relation to the presence or absence of choledocholithiasis or a dilated cystic duct. Small stones (1-4 mm diameter) must migrate to initiate and facilitate further migration; some must increase in size in the common bile duct. Increased biliary pressure consequently dilates the duct system retrogradely, allowing larger stones to follow. Patients at risk of stone migration and thereby pancreatitis and jaundice have large ducts that can be detected by ultrasound assessment.