Quantification of cormorant litter and nutrient deposition to Great Lakes island ecosystems

Black spots for aquatic and terrestrial ecosystems: impact of a perennial cormorant colony on the environment

“…As demonstrated previously, the nutrient content is usually correlated with the number of birds at the colony (Ligęza and Smal, 2003;Hobara et al, 2005;Rush et al, 2013;Klimaszyk et al, 2015), this pattern was also observed in the present study. The increased chemical content found at the former colony (also within deeper soil layers) highlights that the effect of cormorants on soil transformation (and consequently, biological changes) can be long-lasting.…”

Status of Lichens and Bryophytes on Middle Island: Declining Carolinian Habitat at Canada's Southernmost Point

“…The levels of nutrients and changes in pH, even in areas with a low density of nests where nutrients may be insufficient to be directly toxic, may have shifted growing conditions beyond the tolerance ranges of most forest lichen and bryophyte species. The prospects for forest-habitat recovery are uncertain (Herbert et al 2014, Koh et al 2012, Rush et al 2013, and for sensitive species (such as bryophytes and lichens) it may be particularly slow. In Poland, Żółkoś et al (2013) observed some recolonization by epiphytic forest-lichen species after nest sites were abandoned by Ardea cinerea L. (Grey Herons), but found that community composition was altered in the long term.…”

“…Observations showed that nest density was negatively correlated with forest cover (Boutin et al 2011, Hebert et al 2005, Kolb et al 2012) and vascular plant species-richness (Kolb et al 2012), and positively correlated with tree-damage indices (Koh et al 2012), soil acidity, and soil-nutrient levels (phosphorus, nitrogen) (Rush et al 2011(Rush et al , 2013. These changes transformed resident floral and faunal communities by killing individuals and/or by altering growing conditions.…”

“…These changes transformed resident floral and faunal communities by killing individuals and/or by altering growing conditions. In 2008, Parks Canada initiated a Cormorant-reduction program that decreased nest density to ~200 nests/ha (Hebert et al 2014), but the current population continues to impair restoration potential on the island (Boutin et al 2011;Koh et al 2012;Rush et al 2011Rush et al , 2013. Diversity and abundance of vascular plants on Middle Island, including rare species, have declined, presumably due to the effects of Cormorant presence (Aquila Applied Ecologists 2007, Boutin et al 2011, Hebert et al 2005, North-South Environmental 2004.…”

The complexity of ecological impacts induced by great cormorants

“…Over time cormorants, especially in dense colonies, increase N and P content in soil layers to extreme extents (Ligęza & Smal, 2003;Hobara et al, 2005;Kolb et al, 2012;Rush et al, 2013;Litaor et al, 2014;Klimaszyk et al, 2015b). However, even a small cormorant flock can induce a short-term rise in their concentrations, usually restricted to period the birds are present (Klimaszyk et al, 2015b).…”