Reynolds [ 89] developed a model to mimic the flocking behaviour of birds using three simple rules: collision avoidance with flockmates, velocity matching with nearby flockmates and flock centring to stay close to the flock [ 90, 91].
Host birds use two techniques.
It has been postulated based on a variety of theoretical considerations that birds use two separate sets of photoreceptors for detection of chromatic and luminance signals, the single cones and double cones, respectively [5], [6].
We analysed the birds' behaviour using two data sets: the first combined all marked birds (36 males and 30 females), and the second combined only pairs with both partners marked (18 pairs).
We estimated the probability of detecting at least one infected bird at time of slaughter (56 days after birds enter the barn) using two different tests, rt-PCR and an HI assay.
We apply multi-node analyses to the prioritization of habitat patches for five vulnerable bird species in Catalonia, Spain, using two different approaches to connectivity, based on fragmentation and reachability.
Candidate genes were initially screened to determine which showed greatest variation in expression between stages of follicle development using two 4-bird pools of anterior stroma, 5 6 mm, 6 8 mm, and F4 material taken from layers.
Migratory birds may use two electromagnetic tools to find their destinations: one that is entirely innate and another that relies on experience.
The point of emigration at the start of natal dispersal in individual birds was estimated using twelve methods (Table 1).
Modern birds use only two pigments, red and blue, to create all of the various egg colors, spots, and speckles.
