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Red Crossbill, percna subspecies

Knowledge Gaps

As indicated, very little is known about the percna subspecies. In order to fully assess potential threats, limiting factors, and recovery methods, as well as determine measures to evaluate recovery, much more information is required. It may be possible to begin assessing some potential threats, limiting factors, and recovery procedures before all current knowledge gaps are filled.

Specific knowledge gaps that are considered a priority for study focus on five areas:

  1. Taxonomy
  2. Habitat associations
  3. Movement and distribution
  4. Demography and behaviour
  5. Threats

The specific questions felt to be most important for instigating recovery at this time are:

1.  Taxonomy:

a.      Does the percna subspecies still exist in Newfoundland?

b.     Are there other subspecies of Red Crossbill in Newfoundland?

c.      Can we develop a simple technique for subspecies identification?

2.   Habitat associations:

a.      What is preferred habitat for foraging, roosting, and nesting, and do these preferences change seasonally?

                        i. On a fine scale, are there preferences for specific canopy cover, cone density per tree, tree species selection, and/or location for nests in a tree?

                       ii. On a larger scale, are there preferences for stand type and/or patch size? Is there evidence of edge effect?

b.     How does proximity to food sources affect nest site selection?

c.      What proportion of the landscape is required to have optimal cone availability for long-term viability of the population?

d.     What is the spatial distribution of percna habitat on the island of Newfoundland, and how is this forecasted to change over the long term?

e.      What impacts (positive or negative) are anthropogenic and non-anthropogenic factors having on these habitats?

f.       Should the extent and/or quality of available habitat be improved, and if so, what methods should be used?

3. Movement and distribution:

  1. Does percna emigrate or immigrate?
  2. Do other subspecies immigrate and emigrate to and from insular Newfoundland?
  3. What proportion of the Newfoundland population is percna?
  4. What is the home range size for percna?

4. Demography and behaviour:

  1. What are current age-specific survival and fecundity rates and modelled rates of increase?
  2. What behaviours could be potentially limiting to percna success?
  3. Is percna semi-colonial?

5. Threats:

  1. What are the effects of predators and competitors on percna?
  2. Is there correlation between insect (specifically spruce budworm)–related cone damage and Red Crossbill population levels in Newfoundland?
  3. Have forest fires, fire suppression, or pine diseases impacted Red Crossbill populations in Newfoundland?
  4. Do current forest management practices impact Red Crossbill populations in Newfoundland?
  5. Do current agricultural and urbanization practices impact Red Crossbill populations in Newfoundland?
  6. Is there evidence of Allee effects affecting Red Crossbill populations in Newfoundland?
  7. Do cumulative effects of many, some, or all of the above factors impact Red Crossbills in Newfoundland?