Warsaw University of Life Sciences


Furthermore, motor diversity constitutes a proximate link between diet generalism and innovativeness. Acrobatic display behaviour is sexually selected in manakins (Pipridae) and can place high demands on many neural systems.


We show here that relative size of the neostriatum and whole brain distinguish the true and borderline categories in birds using tools to obtain food or water. From two sources, the specialized literature on tools and an innovation data base gathered in the short note sections of 68 journals in 7 areas of the world, we collected 39 true (e.g. use of probes, hammers, sponges, scoops) and 86 borderline (e.g. bait fishing, battering and dropping on anvils, holding with wedges and skewers) cases of tool use in 104 species from 15 parvorders. True tool users have a larger mean residual brain size (regressed against body weight) than do users of borderline tools, confirming the distinction in the literature. In multiple regressions, residual brain size and residual size of the neostriatum (one of the areas in the avian telencephalon thought to be equivalent to the mammalian neocortex) are the best predictors of true tool use reports per taxon.

Comparisons between myriapod assemblages at mine sites in Upper and Lower Lusatia that had different soil and age conditions revealed that myriapods are good indicators of biological soil quality and are reliable and easy to use. Using soil sampling and subsequent heat extraction of animals, four alder stands in the wetlands of the Biebrza, Narew and Bia³owieŜa national parks, north-eastern Poland, were surveyed for millipedes and centipedes. Among 12 millipede species revealed, Xestoiulus laeticollis, Polydesmus complanatus and Craspedosoma rawlinsii occurred and predominated in all alder woods.

The presence of saprophagous millipede species showed a clear succession in parallel with mine-site development, but there is no species with true pioneer behaviour. Centipedes – with Lamyctes emarginatus as a true pioneer – as predators behave less predictably; Geophilomorphs, hunting in the subsoil, are the last to invade. After 50 years of development of mine-site woodlands, five species of millipedes and six species of centipedes, though common in adjacent reference woodlands, had not yet colonised the mine sites.

Soil zoological investigations at soil monitoring sites are carried out with the objective to track changes in the soil’s habitat function. At 60 soil-monitoring sites in north-western Germany, earthworms and microannelids (enchytraeids, tubificids and polychaetes) are currently being used as system indicators for the soil biota. Investigations started 1992, followed by re-investigations every 5 to 10 years. Variations in abundance, biomass and species number of annelids are assessed with respect to nondirectional fluctuations or directional changes, caused by natural variations of environmental factors or due to management practices. The sites are grouped according to land-use type and site condition into six different categories for which typical ranges of variation of the zoological parameters can be distinguished (reference ranges).

  • We go on to propose a model that reconciles the possible (but perhaps controversial) existence of positive associations between cognition and innovation at the cross-taxon level with inconsistent associations at the within-species level.
  • Our results demonstrate that birds are more frequent tool users than usually thought and that the complex cognitive processes involved in tool use may have repeatedly co-evolved with large brains in several orders of birds.
  • Behavioral innovations, the invention of new behaviors or the use of preexisting ones in new contexts, are increasingly considered an essential source of behavioral plasticity, yet the mechanisms by which they arise are poorly understood.
  • Innovation rate is the best predictor of borderline tool use distribution.
  • The detection of substantial changes of the community is based mainly on the species composition, but is supported by quantitative parameters using the reference ranges.

Manakin displays vary across species in terms of behavioural complexity, differing in number of unique motor elements, production of mechanical sounds, cooperation between displaying males, and construction of the display site. Historically, research emphasis has been placed on neurological specializations for vocal aspects of courtship, and less is known about the control of physical, non-vocal displays. By examining brain evolution in relation to extreme acrobatic feats such as manakin displays, we can vastly expand our knowledge of how sexual selection acts on motor behaviour.

By these standards, a vulture breaking an egg by hitting it with a stone uses a tool, but a gull dropping an egg on a rock does not. This distinction between true and borderline (or proto-tool) cases has been criticized for its arbitrariness and anthropocentrism.

Karger AG, Basel. A further intensive study was made with millipedes and centipedes which need – like earthworms – a longer time for immigration.


We draw attention to the high degree of inconsistency among empirical findings relating interindividual variation in innovativeness to interindividual variation in learning performance. We go on to propose a model that reconciles the possible (but perhaps controversial) existence of positive associations between cognition and innovation at the cross-taxon level with inconsistent associations at the within-species level.

gerd knaebe

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