All statistics are based on contigs of size >= 500 bp, unless otherwise noted (e.g., "# contigs (>= 0 bp)" and "Total length (>= 0 bp)" include all contigs).
Suggestion: all assemblies contain continuous fragments of N's of length >= 10 bp. You may consider rerunning QUAST using --scaffolds (-s) option!

Assembly                    duck4-10k.1  duck4-10k.2  duck4.1     duck4.2   
# contigs (>= 0 bp)         15361        15356        315013      315011    
# contigs (>= 1000 bp)      15361        15356        315013      315011    
# contigs (>= 5000 bp)      15361        15356        50433       50430     
# contigs (>= 10000 bp)     15361        15356        15361       15356     
# contigs (>= 25000 bp)     3350         3347         3350        3347      
# contigs (>= 50000 bp)     1541         1541         1541        1541      
Total length (>= 0 bp)      1397407710   1396117256   2205550088  2204281463
Total length (>= 1000 bp)   1397407710   1396117256   2205550088  2204281463
Total length (>= 5000 bp)   1397407710   1396117256   1634904607  1633635896
Total length (>= 10000 bp)  1397407710   1396117256   1397407710  1396117256
Total length (>= 25000 bp)  1225188922   1223948455   1225188922  1223948455
Total length (>= 50000 bp)  1164206709   1163079517   1164206709  1163079517
# contigs                   15361        15356        315013      315011    
Largest contig              13378076     13404639     13378076    13404639  
Total length                1397407710   1396117256   2205550088  2204281463
GC (%)                      33.75        33.75        33.92       33.91     
N50                         1607401      1615007      177022      172688    
N75                         373014       372478       4745        4743      
L50                         216          216          834         837       
L75                         627          627          54388       54452     
# N's per 100 kbp           14275.16     14288.10     9137.01     9142.12